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Sample records for extended free-volume defects

  1. Topological defects in extended inflation

    International Nuclear Information System (INIS)

    Copeland, E.J.; Kolb, E.W.; Chicago Univ., IL; Liddle, A.R.

    1990-04-01

    We consider the production of topological defects, especially cosmic strings, in extended inflation models. In extended inflation, the Universe passes through a first-order phase transition via bubble percolation, which naturally allows defects to form at the end of inflation. The correlation length, which determines the number density of the defects, is related to the mean size of bubbles when they collide. This mechanism allows a natural combination of inflation and large-scale structure via cosmic strings. 18 refs

  2. Topological defects in extended inflation

    International Nuclear Information System (INIS)

    Copeland, E.J.; Kolb, E.W.; Liddle, A.R.

    1990-01-01

    We consider the production of topological defects, especially cosmic strings, in extended-inflation models. In extended inflation, the Universe passes through a first-order phase transition via bubble percolation, which naturally allows defects to form at the end of inflation. The correlation length, which determines the number density of the defects, is related to the mean size of the bubbles when they collide. This mechanism allows a natural combination of inflation and large-scale structure via cosmic strings

  3. Multicomponent diffusivities from the free volume theory

    NARCIS (Netherlands)

    Wesselingh, J.A; Bollen, A.M

    In this paper the free volume theory of diffusion is extended to multicomponent mixtures. The free volume is taken to be accessible for any component according to its surface. fraction. The resulting equations predict multicomponent (Maxwell-Stefan) diffusivities in simple liquid mixtures from pure

  4. Delineation of Crystalline Extended Defects on Multicrystalline Silicon Wafers

    Directory of Open Access Journals (Sweden)

    Mohamed Fathi

    2007-01-01

    Full Text Available We have selected Secco and Yang etch solutions for the crystalline defect delineation on multicrystalline silicon (mc-Si wafers. Following experimentations and optimization of Yang and Secco etching process parameters, we have successfully revealed crystalline extended defects on mc-Si surfaces. A specific delineation process with successive application of Yang and Secco agent on the same sample has proved the increased sensitivity of Secco etch to crystalline extended defects in mc-Si materials. The exploration of delineated mc-Si surfaces indicated that strong dislocation densities are localized mainly close to the grain boundaries and on the level of small grains in size (below 1 mm. Locally, we have observed the formation of several parallel dislocation lines, perpendicular to the grain boundaries. The overlapping of several dislocations lines has revealed particular forms for etched pits of dislocations.

  5. A nanoscale characterisation of extended defects in glassy-like As 2Se 3 semiconductors with PAL technique

    Science.gov (United States)

    Shpotyuk, O.; Kovalskiy, A.; Filipecki, J.; Hyla, M.; Kozdras, A.

    2003-12-01

    A meaningful interpretation of positron lifetime characteristics for glassy-like g-As2Se3 is developed taking into account calculations of Jensen et al. (J. Non-Cryst. Solids 170 (1994) 57) for positrons trapped by free-volume extended defects in orthorhombic As2Se3 and void volume distribution for 146-atoms layer-biased model of amorphous As2Se3 presented by Popescu (J. Non-Cryst. Solids 35-36 (1980) 549). The obtained results are compared for samples having different thermal pre-history. Two groups of experimental results with close lifetime characteristics are distinguished for each of the investigated samples. This feature is explained in terms of average positron lifetime by applying two-state positron trapping model for mathematical treatment of the obtained spectra.

  6. Graphene valley pseudospin filter using an extended line defect

    Science.gov (United States)

    Gunlycke, Daniel; White, Carter

    2011-03-01

    Although graphene exhibits excellent electron and thermal transport properties, it does not have an intrinsic band gap, required to use graphene as a replacement material for silicon and other semiconductors in conventional electronics. The band structure of graphene with its two cones near the Fermi level, however, offers opportunities to develop non-traditional applications. One such avenue is to exploit the valley degeneracy in graphene to develop valleytronics. A central component in valleytronics is the valley filter, just as the spin filter is central in spintronics. Herein, we present a two-dimensional valley filter based on scattering of electrons and holes off a recently observed extended line defect [Nat. Nanotech.5, 326 (2010)] within graphene. The transmission probability depends strongly on the valley pseudospin and the angle of incidence of the incident quasiparticles. Quasiparticles arriving at the line defect at a high angle of incidence lead to a valley polarization of the transmitted beam that is near 100 percent. This work was supported by ONR, directly and through NRL.

  7. Mechanism of Na accumulation at extended defects in Si from first-principles

    Science.gov (United States)

    Park, Ji-Sang; Chan, Maria K. Y.

    2018-04-01

    Sodium (Na) impurities in silicon solar cells are considered to play an important role in potential-induced degradation (PID), a significant cause of solar cell degradation and failure. Shorting due to Na accumulation at extended defects has been suggested as a culprit for PID. However, it is not clear how the extended defects are decorated by Na impurities. Using first-principles density functional theory calculations, we find that Na impurities segregate from the bulk into extended defects such as intrinsic stacking faults and Σ3 (111) grain boundaries. The energy barrier required for Na to escape from the extended defects is substantial and similar to the sum of the barrier energy in bulk Si (1.1-1.2 eV) and the segregation energy to the stacking fault (˜0.7 eV). Surprisingly, the migration barrier for Na diffusion within the extended defects is even higher than the energy barrier for escaping. The results suggest that the extended defects likely accumulate Na as the impurities segregate to the defects from the bulk, rather than because of migration through the extended defects.

  8. Barrier controlled carrier trapping of extended defects in CdZnTe detector

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Rongrong [State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi' an, Shaanxi 710072 (China); Jie, Wanqi, E-mail: jwq@nwpu.edu.cn [State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi' an, Shaanxi 710072 (China); Xu, Yadong [State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi' an, Shaanxi 710072 (China); Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Yu, Hui; Zha, Gangqiang; Wang, Tao; Ren, Jie [State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi' an, Shaanxi 710072 (China)

    2015-09-11

    Transient current techniques using alpha particle source were utilized to study the influence of extended defects on the electron drift time and the detector performance of CdZnTe crystals. Different from the case of trapping through isolated point defect, a barrier controlled trapping model was used to explain the mechanism of carrier trapping at the extended defects. The effect of extended defects on the photoconductance was studied by laser beam induced transient current (LBIC) measurement. The results demonstrate that the Schottky-type depletion space charge region is induced at the vicinity of the extended defects, which further distorts the internal electric field distribution and affects the carrier trajectory in CdZnTe crystals. The relationship between the electron drift time and detector performance has been established. - Highlights: • The barrier controlled trapping model was developed around extended defects. • Electron mobility and E-field distribution were distorted by space charge depletion region. • Extended defects act as a recombination-activated region. • The relationships between extended defects and detector performance were established.

  9. A nanoscale characterisation of extended defects in glassy-like As{sub 2}Se{sub 3} semiconductors with PAL technique

    Energy Technology Data Exchange (ETDEWEB)

    Shpotyuk, O.; Kovalskiy, A.; Filipecki, J.; Hyla, M.; Kozdras, A

    2003-12-31

    A meaningful interpretation of positron lifetime characteristics for glassy-like g-As{sub 2}Se{sub 3} is developed taking into account calculations of Jensen et al. (J. Non-Cryst. Solids 170 (1994) 57) for positrons trapped by free-volume extended defects in orthorhombic As{sub 2}Se{sub 3} and void volume distribution for 146-atoms layer-biased model of amorphous As{sub 2}Se{sub 3} presented by Popescu (J. Non-Cryst. Solids 35-36 (1980) 549). The obtained results are compared for samples having different thermal pre-history. Two groups of experimental results with close lifetime characteristics are distinguished for each of the investigated samples. This feature is explained in terms of average positron lifetime by applying two-state positron trapping model for mathematical treatment of the obtained spectra.

  10. Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope.

    Science.gov (United States)

    Hieckmann, Ellen; Nacke, Markus; Allardt, Matthias; Bodrov, Yury; Chekhonin, Paul; Skrotzki, Werner; Weber, Jörg

    2016-05-28

    Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared.

  11. Manipulation of native point defect behavior in rutile TiO2 via surfaces and extended defects

    Science.gov (United States)

    Gilliard, Kandis Leslie; Seebauer, Edmund G.

    2017-11-01

    Semiconductor surfaces offer efficient pathways for exchanging native point defects with the underlying bulk. For rutile TiO2(1 1 0), isotopic self-diffusion studies of oxygen have suggested that the surface may act as a source for Oi while simultaneously acting as a sink for titanium interstitials Tii. Through self-diffusion measurements with labeled Ti as well as O, the present work develops a more complete picture of the diffusion-reaction network involving Oi and Tii, complete with the surface acting as a source for whichever elements are available from the gas phase and a sink for elements that are not. The picture points to the importance of extended defects such as platelets and crystallographic shear planes as reservoirs of Oi and Tii, acting as net sources or sinks of these species depending upon specific conditions. The results exemplify the combined roles of surfaces and extended defects in regulating point defect behavior even in macroscopic metal oxide crystals, and point to specific strategies for manipulating that behavior intentionally.

  12. Ferromagnetically coupled local moments along an extended line defect in graphene

    Science.gov (United States)

    White, Carter T.; Vasudevan, Smitha; Gunlycke, Daniel

    2011-03-01

    Recently an extended line defect was observed composed of octagonal and pentagonal carbon rings embedded in a graphene sheet [Nat. Nanotech. 5, 326 (2010)]. We report results of studies we have made of this defect using both first-principles and semi-empirical methods. Two types of boundary-localized states arising from the defect are identified. The first (second) type has eigenstates with wavefunctions that are anti- symmetric (symmetric) with respect to a mirror plane that is perpendicular to the graphene sheet and passes through the line defect center line. The boundary-localized anti-symmetric states are shown to be intimately connected to the zigzag edge states of semi-infinite graphene. They exhibit little dispersion along the defect line and lie close to the Fermi level giving rise to a spontaneous spin polarization along the defect once electron-electron interactions are included at the level of a mean field approximation to a Hubbard Model. Within this approach, symmetry requires that the principal moments couple ferromagnetically both along and across the line defect leading to approximately 2/3 more up than down spin electrons per defect repeat unit. This work was supported by ONR, directly and through NRL.

  13. Free volumes in bulk nanocrystalline metals studied by the complementary techniques of positron annihilation and dilatometry

    Science.gov (United States)

    Würschum, Roland; Oberdorfer, Bernd; Steyskal, Eva-Maria; Sprengel, Wolfgang; Puff, Werner; Pikart, Philip; Hugenschmidt, Christoph; Pippan, Reinhard

    2012-01-01

    Free-volume type defects, such as vacancies, vacancy-agglomerates, dislocations, and grain boundaries represent a key parameter in the properties of ultrafine-grained and nanocrystalline materials. Such free-volume type defects are introduced in high excess concentration during the processes of structural refinement by severe plastic deformation. The direct method of time-differential dilatometry is applied in the present work to determine the total amount and the kinetics of free volume by measuring the irreversible length change upon annealing of bulk nanocrystalline metals (Fe, Cu, Ni) prepared by high-pressure torsion (HPT). In the case of HPT-deformed Ni and Cu, distinct substages of the length change upon linear heating occur due to the loss of grain boundaries in the wake of crystallite growth. The data on dilatometric length change can be directly related to the fast annealing of free-volume type defects studied by in situ Doppler broadening measurements performed at the high-intensity positron beam of the FRM II (Garching, Munich, Germany). PMID:23471443

  14. Crystalline quality of the trigonal piezoelectric materials and effects of the extended defects.

    Science.gov (United States)

    Capelle, Bernard; Detaint, Jacques; Epelboin, Yves

    2012-05-01

    Many frequently used or promising piezoelectric materials belong to crystal classes 32 or 3m. Among them are α quartz and its crystallographic analogs (AlPO(4), GaPO(4), α-GeO(2), etc.), the numerous materials of the langasite (La-(3)Ga(5)SiO,sub>14) family and also lithium tantalate (LiTaO,sub>3) and lithium niobate (LiNbO 3). In this paper we study the present state of the art for these materials, indicate their principal point and extended defects, and present methods to reduce the dislocation density. Large concentrations of intrinsic point defects often exist in crystal grown at very high temperatures. The point defects (intrinsic or related to impurities) modify the constants and can increase the acoustic losses. This is the case for the alkali ions and the OH that induce severe losses in different temperature intervals. The extended defects also affect the performances of the piezoelectric devices. Some, such as twins, ferroelectric domains, or large solid or liquid inclusions, have very detrimental effects. Dislocations, growth bands, and planar defects are more difficult to avoid and affect the devices in a more subtle manner. In quartz and its analogs, dislocations seem to increase the nonlinear elastic effects and have a collective effect on the vibration modes, particularly in energy trapping resonators. Growth bands and stacking faults also produce similar effects.

  15. Reconstruction of complex thoraco-abdominal defects with extended anterolateral thigh flap

    Directory of Open Access Journals (Sweden)

    Yadav Prabha

    2010-01-01

    Full Text Available Background: The reconstruction of complex thoraco-abdominal defects following tumour ablative procedures has evolved over the years from the use of pedicle flaps to free flaps. The free extended anterolateral thigh flap is a good choice to cover large defects in one stage. Materials and Methods: From 2004 to 2009, five patients with complex defects of the thoracic and abdominal wall following tumour ablation were reconstructed in one stage and were studied. The commonest tumour was chondrosarcoma. The skeletal component was reconstructed with methylmethacrylate bone cement and polypropylene mesh and the soft tissue with free extended anterolateral thigh flap. The flaps were anastomosed with internal mammary vessels. The donor sites of the flaps were covered with split-skin graft. Result: All the flaps survived well. One flap required re-exploration for venous congestion and was successfully salvaged. Two flaps had post operative wound infection and were managed conservatively. All flap donor sites developed hyper-pigmentation, contour deformity and cobble stone appearance. Conclusion: Single-stage reconstruction of the complex defects of the thoraco-abdominal region is feasible with extended anterolateral thigh flap and can be adopted as the first procedure of choice.

  16. Membranes with artificial free-volume for biofuel production

    Science.gov (United States)

    Petzetakis, Nikos; Doherty, Cara M.; Thornton, Aaron W.; Chen, X. Chelsea; Cotanda, Pepa; Hill, Anita J.; Balsara, Nitash P.

    2015-01-01

    Free-volume of polymers governs transport of penetrants through polymeric films. Control over free-volume is thus important for the development of better membranes for a wide variety of applications such as gas separations, pharmaceutical purifications and energy storage. To date, methodologies used to create materials with different amounts of free-volume are based primarily on chemical synthesis of new polymers. Here we report a simple methodology for generating free-volume based on the self-assembly of polyethylene-b-polydimethylsiloxane-b-polyethylene triblock copolymers. We have used this method to fabricate a series of membranes with identical compositions but with different amounts of free-volume. We use the term artificial free-volume to refer to the additional free-volume created by self-assembly. The effect of artificial free-volume on selective transport through the membranes was tested using butanol/water and ethanol/water mixtures due to their importance in biofuel production. We found that the introduction of artificial free-volume improves both alcohol permeability and selectivity. PMID:26104672

  17. Extended Islanded Reverse Sural Artery flap for Staged Reconstruction of Foot Defects Proximal to Toes.

    Science.gov (United States)

    Yousaf, Muhammad Amin; Abidin, Zain Ul; Khalid, Kamran; Haq, Ata Ul; Khalid, Farrukh Aslam; Tarar, Faraz Ahmad; Asif, Muhammad Umar; Tarar, Moazzam Nazeer

    2018-02-01

    Obective:To assess the outcome of extended delayed reverse sural artery flap for reconstruction of foot defects proximal to toes in terms of flap survival, complication and extended area. Case series. Jinnah Burn and Reconstructive Surgery Centre, Lahore, from February 2015 to April 2017. Cases who underwent delayed sural artery flap were inducted. Preoperative hand-held doppler was done to confirm the location of perforator. Two suitable perforators were chosen to raise the extended flap by crossing the proximal limit in all cases. The pedicle was kept minimum 3 cm wide and perfusion was assessed. Flap was delayed for one week and vaccum-assisted closure (VAC) dressing was applied over wound. The second surgery was performed after one week. Proximal perforator was clamped and ligated after checking adequate perfusion of flap. Flap was insetted into defect. Thirty-two patients were reconstructed with delayed reverse sural artery flap. The mean age of the patients was 26.5 12.2 years. Twenty-four (75%) patients were males and 8 (25%) were females. Twenty-two (68.7%) cases were degloving wounds after road traffic accidents (RTA), 6 (18.7%) were diabetic foot wounds, 4 (12.5%) sustained injury after falling from height and 7 (21.8%) patients had fracture of metatarsals. Twenty-eight flaps were transferred after one week delay, and only in 4 cases, flap were transferred after two weeks. All flaps survived completely. Complications of infection noted in 3 (9.3%) flaps, 3 (9.3%) flaps showed tip necrosis, 2 (6.2%) flaps undergone epidermolysis and only 2 (6.2%) showed venous congestion. Delayed islanded reverse sural artery perforator flap is a reliable and versatile option for resurfacing soft tissue defects of lower limb proximal to the toes with lesser complications and extended coverage area.

  18. Extended Islanded Reverse Sural Artery Flap for Staged Reconstruction of Foot Defects Proximal to Toes

    International Nuclear Information System (INIS)

    Yousaf, M.A.; Abidin, Z.U.; Khalid, K.; Haq, A.U.; Tarar, F.A.; Asif, M.U.; Tarar, M.N.

    2018-01-01

    To assess the outcome of extended delayed reverse sural artery flap for reconstruction of foot defects proximal to toes in terms of flap survival, complication and extended area. Study Design:Case series. Place and Duration of Study:Jinnah Burn and Reconstructive Surgery Centre, Lahore, from February 2015 to April 2017. Methodology:Cases who underwent delayed sural artery flap were inducted. Preoperative hand-held doppler was done to confirm the location of perforator. Two suitable perforators were chosen to raise the extended flap by crossing the proximal limit in all cases. The pedicle was kept minimum 3 cm wide and perfusion was assessed. Flap was delayed for one week and vaccum-assisted closure (VAC) dressing was applied over wound. The second surgery was performed after one week. Proximal perforator was clamped and ligated after checking adequate perfusion of flap. Flap was insetted into defect. Results:Thirty-two patients were reconstructed with delayed reverse sural artery flap. The mean age of the patients was 26.5 +12.2 years. Twenty-four (75%) patients were males and 8 (25%) were females. Twenty-two (68.7%) cases were degloving wounds after road traffic accidents (RTA), 6 (18.7%) were diabetic foot wounds, 4 (12.5%) sustained injury after falling from height and 7 (21.8%) patients had fracture of metatarsals. Twenty-eight flaps were transferred after one week delay, and only in 4 cases, flap were transferred after two weeks. All flaps survived completely. Complications of infection noted in 3 (9.3%) flaps, 3 (9.3%) flaps showed tip necrosis, 2 (6.2%) flaps undergone epidermolysis and only 2 (6.2%) showed venous congestion. Conclusion:Delayed islanded reverse sural artery perforator flap is a reliable and versatile option for resurfacing soft tissue defects of lower limb proximal to the toes with lesser complications and extended coverage area. (author)

  19. Free-volume characterization of nanostructurized substances by positron annihilation lifetime spectroscopy

    Science.gov (United States)

    Shpotyuk, O.; Ingram, A.; Shpotyuk, Ya.

    2018-02-01

    Methodological possibilities of positron annihilation lifetime (PAL) spectroscopy are examined to parameterize free-volume structural evolution processes in some nanostructurized substances obeying conversion from positronium (Ps) decaying to positron trapping. Unlike conventional x3-term fitting analysis based on admixed positron trapping and Ps decaying, the effect of nanostructurization is considered as occurring due to conversion from preferential Ps decaying in initial host matrix to positron trapping in modified (nanostructurized) host-guest matrix. The developed approach referred to as x3-x2-CDA (coupling decomposition algorithm) allows estimation defect-free bulk and defect-specific positron lifetimes of free-volume elements responsible for nanostructurization. The applicability of this approach is proved for some nanostructurized materials allowing free-volume changes through Ps-to-positron trapping conversion, such as (i) metallic Ag nanoparticles embedded in polymer matrix, (ii) structure-modification processes caused by swift heavy ions irradiation in polystyrene, and (iii) host-guest chemistry problems like water immersion in alumomagnesium spinel ceramics. This approach is considered to be used as test-indicator, separating processes of host-matrix nanostructurization due to embedded nanoparticles from uncorrelated changes in positron-trapping and Ps-decaying channels.

  20. Modelisation of the growth of extended defects created by electron irradiation in CdTe

    International Nuclear Information System (INIS)

    Gue, A.M.; Esteve, D.; Mazel, A.

    1989-01-01

    After a brief review of the experimental features of dislocation loops created in cadmium telluride by high energy electron irradiation, we present a theoretical modelisation of the growth of extended defects. The basic method of the Chemical Reaction Rate Theory has been modified in order to take into account: the instability of small clusters, the effects of surfaces, the fact that CdTe is a binary compound. The comparison between theoretical and experimental results leads us to conclude that the vacancy-interstitial recombination energy (E v ) is different from the diinterstitial formation energy (E i ). The values of these energies have been determined: E i =.35eV, E v =.25eV, E d =1.1eV (small clusters dissociation energy). This work has also shown that the lake of dislocation loops at high irradiation temperature (T>480K) is not only a thin film effect but is due to clusters instability [fr

  1. Atomistic models of amorphous polybutadienes; 3 -- Static free volume

    Energy Technology Data Exchange (ETDEWEB)

    Misra, S.; Mattice, W.L. [Univ. of Akron, OH (United States). Inst. of Polymer Science

    1993-12-20

    Atomistic models of polybutadiene have been generated using molecular mechanics and molecular dynamics at a bulk density of 0.89 g cm{sup {minus}3}. Four microstructures formed by cis-1,4-polybutadiene, trans-1,4-polybutadiene, 1,2-polybutadiene, and a random copolymer of the three (55% trans, 35% cis, and 10% vinyl) are analyzed for static free volume. The free volume is determined by hard spherical probes that see the atoms as hard spheres of radii which equal 89% of their van der Waals radii. The total free volume, the free volume distribution, and the shape of the voids are analyzed for all four microstructures. The accessible free volume as a function of the probe size is found to be characteristic of voids in disordered packings of hard spheres. The free volume distributions have some common features across the microstructures. In particular, the free volume distributions as probed by a 1-{angstrom} radius probe show void size concentrations around {approximately}7.5 and 15 {angstrom}{sup 3} (with the exception of trans-polybutadiene, which does not display the latter). The shape factors for all four structures decay to the same asymptotic value of 0.67 {+-} 0.1 over the size range of 0--5 {angstrom}{sup 3}. There is a marked difference in the asphericity and the acylindricity of voids in the four microstructures. Analysis of randomly generated shapes suggests that the voids in the polymer microstructures are mostly elongated in comparison with randomly ``grown`` cavities, probably due to the connectivity of the polymer chains.

  2. Free volume modifications in chalcone chromophore doped PMMA films by electron irradiation: Positron annihilation study

    Science.gov (United States)

    Ismayil; Ravindrachary, V.; Praveena, S. D.; Mahesha, M. G.

    2018-03-01

    The free volume related fluorescence behaviour in electron beam irradiated chalcone chromophore doped Poly(methyl methacrylate) (PMMA) composite films have been studied using FTIR, UV-Visible, XRD and Positron Annihilation techniques. From the FTIR spectral study it is found that the formation of polarons and bipolaron takes place due to cross linking as well as chain scission processes at lower and higher doses respectively. It reveals that the formation of various polaronic defect levels upon irradiation is responsible for the creation of three optical energy band gaps within the polymer films as obtained from UV-Visible spectra. The crosslinking process at lower doses increases the distance between the pendant groups to reduce the interchain distance and chain scission process at higher doses decreases interchain separation to enhance the number of polarons in the polymer composites as suggested by XRD studies. The fluorescence studies show the enhancement of fluorescence emission at lower doses and reduction at higher doses under electron irradiation. The positron annihilation study suggests that the low radiation doses induce crosslinking which affect the free volume properties and in turn hinders the chalcone molecular rotation within the polymer composite. At higher doses chain scission process support polymer matrix relaxation and facilitates non-radiative transition of the chromophore upon excitation. This study shows that fluorescence enhancement and mobility of chromophore within the polymer matrix is directly related to the free volume around it.

  3. Free volume sizes in intercalated polyamide 6/clay nanocomposites

    DEFF Research Database (Denmark)

    Wiinberg, P.; Eldrup, Morten Mostgaard; Pedersen, N.J.

    2005-01-01

    The effect of incorporating modified clay into a polyamide 6 (PA6) matrix, on the free volume cavity sizes and the thermal and viscoelastic properties of the resulting nanocomposite, was studied with positron annihilation lifetime spectroscopy, differential scanning calorimetry and dynamic...... response of PA6/clay nanocomposites, as compared to unfilled PA6, pointed towards a changed mobility in the non-crystalline regions. At high concentrations of clay (> 19 wt%) an increase of the free volume cavity diameter was observed, indicating a lower chain packing efficiency in the PA6/clay...... nanocomposites. The increased free volume sizes were present both above and below the glass transition temperature of PA6. (c) 2005 Elsevier Ltd. All rights reserved....

  4. Free volume dilatation in polymers by ortho-positronium

    DEFF Research Database (Denmark)

    Winberg, P.; Eldrup, Morten Mostgaard; Maurer, F.H.J.

    2012-01-01

    The possibility of positronium induced free volume cavity expansion in some polymers above the glass transition temperature was investigated using experimental positron annihilation lifetime data from the literature for polydimethylsiloxane, polyisobutylene, and polybutadiene as function of tempe......The possibility of positronium induced free volume cavity expansion in some polymers above the glass transition temperature was investigated using experimental positron annihilation lifetime data from the literature for polydimethylsiloxane, polyisobutylene, and polybutadiene as function...... of temperature. The results suggest that free volume sites can expand towards an equilibrium size, determined as the equilibrium Ps-bubble size defined earlier for low-molecular-weight liquids. The expansion can be explained by the increase of molecular mobility and hence decrease of relaxation times, which...

  5. Extended defects in MBE-grown CdTe-based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wichrowska, Karolina; Wosinski, Tadeusz; Kret, Slawomir; Chusnutdinow, Sergij; Karczewski, Grzegorz [Institute of Physics, Polish Academy of Sciences, Warsaw (Poland); Rawski, Michal [Analytical Laboratory, Maria Curie-Sklodowska University, Lublin (Poland); Yastrubchak, Oksana [Institute of Physics, Maria Curie-Sklodowska University, Lublin (Poland)

    2015-08-15

    Extended defects in the p -ZnTe/n -CdTe heterojunctions grown by the molecular-beam epitaxy technique on two different substrates, GaAs and CdTe, have been investigated by deep-level transient spectroscopy (DLTS) and transmission electron microscopy (TEM). Four hole traps, called H1 to H4, and one electron trap, called E3, have been revealed in the DLTS spectra measured for the heterojunctions grown on the GaAs substrates. The H1, H3, H4 and E3 traps have been attributed to the electronic states of dislocations on the ground of their logarithmic capture kinetics. The DLTS peaks associated with the H1 and E3 traps were not observed in the DLTS spectra measured for the heterojunction grown on the CdTe substrate. They are most likely associated with threading dislocations generated at the mismatched interface with the GaAs substrate. Cross-sectional TEM images point out that they are dislocations of the 60 -type. In both the types of heterojunctions the H4 trap was observed only under forward-bias filling pulse, suggesting that this trap is associated with the CdTe/ZnTe interface. In addition, TEM images revealed also the presence of intrinsic and extrinsic stacking faults in the CdTe layers, which may considerably affect their electronic properties. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Investigation of point and extended defects in electron irradiated silicon—Dependence on the particle energy

    Energy Technology Data Exchange (ETDEWEB)

    Radu, R.; Pintilie, I.; Nistor, L. C. [National Institute of Materials Physics, Atomistilor 105 bis, Magurele 077125 (Romania); Fretwurst, E.; Lindstroem, G. [Institute for Experimental Physics, University of Hamburg, D-22761 Hamburg (Germany); Makarenko, L. F. [Belarusian State University, Independence Ave. 4, 220030 Minsk (Belarus)

    2015-04-28

    This work is focusing on generation, time evolution, and impact on the electrical performance of silicon diodes impaired by radiation induced active defects. n-type silicon diodes had been irradiated with electrons ranging from 1.5 MeV to 27 MeV. It is shown that the formation of small clusters starts already after irradiation with high fluence of 1.5 MeV electrons. An increase of the introduction rates of both point defects and small clusters with increasing energy is seen, showing saturation for electron energies above ∼15 MeV. The changes in the leakage current at low irradiation fluence-values proved to be determined by the change in the configuration of the tri-vacancy (V{sub 3}). Similar to V{sub 3}, other cluster related defects are showing bistability indicating that they might be associated with larger vacancy clusters. The change of the space charge density with irradiation and with annealing time after irradiation is fully described by accounting for the radiation induced trapping centers. High resolution electron microscopy investigations correlated with the annealing experiments revealed changes in the spatial structure of the defects. Furthermore, it is shown that while the generation of point defects is well described by the classical Non Ionizing Energy Loss (NIEL), the formation of small defect clusters is better described by the “effective NIEL” using results from molecular dynamics simulations.

  7. Positron annihilation spectroscopy (PALS) the effect of crosslinking on free volume size in poly-methyl-methacrylate

    CERN Document Server

    Atevikj, A

    2000-01-01

    Positron annihilation Spectroscopy (PALS) is used for analyzing the samples of polymethyl-methacrylate (PMMA) with different contents of crosslinks. The measurements are performed at room temperature. The times of life (tau sub 1 , tau sub 2 , tau sub 3) and the intensities (I sub I , I sub 2 , 1 sub 3) of para-positronium, the free positrons and the orto-positrons are calculated for each type of polymer, but only (tau sub 3) and (I sub 3) are of interest because we can calculate the size of free volume. It is shown that the radius of free volume is proportional to the crosslinking density. Defects of sizes in the range of 0.1 to 1 nm are detected with Positron Spectroscopy, while other techniques do not give results. (Original)

  8. Transabdominal-pelvic-perineal (TAPP) anterolateral thigh flap: A new reconstructive technique for complex defects following extended abdominoperineal resection.

    Science.gov (United States)

    di Summa, Pietro G; Matter, Maurice; Kalbermatten, Daniel F; Bauquis, Olivier; Raffoul, Wassim

    2016-03-01

    Abdominoperineal resection (APR) following radiotherapy is associated with a high rate of perineal wound complications. The anterolateral thigh (ALT) flap, combined with the vastus lateralis (VL) muscle, can cover complex perineal and pelvic anteroposterior defects. This is used for the first time transabdominally through the pelvis and the perineum (TAPP) in the infero-posterior directions; this technique has been described and illustrated in this study. Among over 90 patients who underwent perineal reconstruction between May 2004 and June 2011, six patients presented high-grade tumours invading perineum, pelvis and sacrum, thereby resulting in a continuous anteroposterior defect. ALT + VL TAPP reconstructions were performed after extended APR and, subsequently, sacrectomy. Patients were examined retrospectively to determine demographics, operative time, complications (general and flap-related), time to complete healing and length of hospital stay. Long-term flap coverage, flap volume stability and functional and aesthetic outcomes were assessed. Mean operating time of the reconstruction was 290 min. No deaths occurred. One patient presented partial flap necrosis. Another patient presented a novel wound dehiscence after flap healing, due to secondary skin dissemination of the primary tumour. Following volumetric flap analysis on serial post-operative CT scans, no significant flap atrophy was observed. All flaps fully covered the defects. No late complications such as fistulas or perineal hernias occurred. Donor-site recovery was uneventful with no functional deficits. The use of the ALT + VL flap transabdominally is an innovative method to reconstruct exceptionally complex perineal and pelvic defects extending up to the lower back. This flap guarantees superior bulk, obliterating all pelvic dead space, with the fascia lata (FL) supporting the pelvic floor. Copyright © 2015 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by

  9. Fifth workshop on the role of impurities and defects in silicon device processing. Extended abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Sopori, B.L.; Luque, A.; Sopori, B.; Swanson, D.; Gee, J.; Kalejs, J.; Jastrzebski, L.; Tan, T.

    1995-08-01

    This workshop dealt with engineering aspects and material properties of silicon electronic devices. Crystalline silicon growth, modeling, and properties are discussed in general and as applied to solar cells. Topics considered in discussions of silicon growth include: casting, string ribbons, Al backside contacts, ion implantation, gettering, passivation, and ultrasound treatments. Properties studies include: Electronic properties of defects and impurities, dopant and carrier concentrations, structure and bonding, nitrogen effects, degradation of bulk diffusion length, and recombination parameters. Individual papers from the workshop are indexed separately on the Energy Data Bases.

  10. Positron annihilation lifetime study of extended defects in semiconductor glasses and polymers

    Energy Technology Data Exchange (ETDEWEB)

    Boyko, Olha [Department of Pediatric Dentistry, Danylo Halytsky Lviv National Medical University, Pekarska str. 69, 79010 Lviv (Ukraine); Shpotyuk, Yaroslav [Department of Optoelectronics and Information Technologies, Ivan Franko National University of Lviv, Dragomanova str. 50, 79005 Lviv (Ukraine); Lviv Scientific Research Institute of Materials, Scientific Research Company ' ' Carat' ' , Stryjska str. 202, 79031 Lviv (Ukraine); Filipecki, Jacek [Institute of Physics, Jan Dlugosz University in Czestochowa, Armii Krajowej al. 13/15, 42200 Czestochowa (Poland)

    2013-01-15

    The processes of atomic shrinkage in network-forming solids initiated by external influences are tested using technique of positron annihilation lifetime spectroscopy at the example of chalcogenide vitreous semiconductors of arsenic sulphide type and acrylic polymers for dental application. Two state positron trapping is shown to be responsible for atomic shrinkage in chalcogenide glasses, while mixed trapping and ortho-positronium decaying is character for volumetric densification and stress propagation in acrylic dental polymers. At the basis of the obtained results it is concluded that correct analysis of externally-induced shrinkage in polymer networks under consideration can be developed by using original positron lifetime data treatment algorithms to compensate defect-free bulk annihilation channel within two-state positron trapping model and account for an interbalance between simultaneously co-existing positron trapping and orth-positronium related decaying channels within mixed three-state positron annihilation model (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Positron annihilation lifetime study of extended defects in semiconductor glasses and polymers

    International Nuclear Information System (INIS)

    Boyko, Olha; Shpotyuk, Yaroslav; Filipecki, Jacek

    2013-01-01

    The processes of atomic shrinkage in network-forming solids initiated by external influences are tested using technique of positron annihilation lifetime spectroscopy at the example of chalcogenide vitreous semiconductors of arsenic sulphide type and acrylic polymers for dental application. Two state positron trapping is shown to be responsible for atomic shrinkage in chalcogenide glasses, while mixed trapping and ortho-positronium decaying is character for volumetric densification and stress propagation in acrylic dental polymers. At the basis of the obtained results it is concluded that correct analysis of externally-induced shrinkage in polymer networks under consideration can be developed by using original positron lifetime data treatment algorithms to compensate defect-free bulk annihilation channel within two-state positron trapping model and account for an interbalance between simultaneously co-existing positron trapping and orth-positronium related decaying channels within mixed three-state positron annihilation model (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. The local free volume and its correlation with the structural, chemical and dynamic properties of branched polymers, polymer electrolytes, highly oriented polyethylene fibres and other polymers

    International Nuclear Information System (INIS)

    Bamford, David

    2002-01-01

    frequently observed levelling off of the expansion of the hole volume at high temperatures is proposed in terms of increased thermal motions of the polymer chain segments on a time scale comparable to the o-Ps lifetime. The ionic conductivity of all the samples was found to follow both the Cohen-Turnbull and Vogel Tamman Fulcher theories over changes in the conductivity of several orders of magnitude demonstrating a direct link between the average free volume hole size and the ionic conductivity. Surprisingly, no clear differences were observed between the single ion and mixed ion conductors, showing the conduction mechanism to be independent of the specific interactions between the ions and the polymer chains. At temperatures near or below the glass transition, a change in the ion transport mechanism from a random redistribution of free volume in the rubbery phase to a thermally activated hopping in the glassy phase is observed. The anisotropic 'free volume hole' shape in highly oriented polyethylene fibres is studied using 2-Dimensional Angular Correlation of Annihilation Radiation spectroscopy and a new method of analysing the data is proposed. The average shape of these holes is determined and bears a remarkable similarity to the expected shape of chain fold defects in the crystalline phase. Finally, the potential use of Doppler Broadening of Annihilation Radiation DBAR spectroscopy as a probe of the chemical surroundings of free volume holes in polymers is assessed. Several series of fluorinated polymers are studied using PALS and DBAR spectroscopy and a linear decrease in the S-parameter of the annihilation peak is observed with increasing fluorine content. Using a new coincidence DBAR spectrometer it was found that the presence of oxygen, fluorine or chlorine in polymers could be identified from subtle but characteristic changes in the shape of the annihilation peak. (author)

  13. Some aspects of free volume studies in molecular substances using positron annihilation experiments

    International Nuclear Information System (INIS)

    Shantarovich, V.P.; Gustov, V.W.; Kevdina, I.B.; Suzuki, T.; Djourelov, N.; Shimazu, A.

    2005-01-01

    Positron annihilation lifetime spectroscopy is accepted now as a method for the studies of elementary free volumes (free volume holes) in solids, in polymers in particular. The aim of this paper is to discuss some problems, the difficulties on the way of this application and to illustrate them by several examples obtained by the authors. (author)

  14. Permeability of gases in polyacetylenes and free volume obtained by positron annihilation lifetime spectroscopy

    International Nuclear Information System (INIS)

    Buriova, M.

    2001-12-01

    Positron annihilation lifetime spectra (PALS) of nine substituted polyacetylenes in vacuum and in air were analysed with aim to determine free volume and influence of the atmosphere. Studied glassy polymers in wide variation of permeability showed bimodal distribution of free volume elements. Good correlation between long-live component(s) of PALS spectra of trialkylsilyl-, denyl- and adamantyl-substituted polyacetylenes and permeability of oxygen and nitrogen is suitable for quickly and non-destructive evaluation of free volume of the polymers and for their screening of membranes. (author)

  15. Free Volume and Gas Permeation in Anthracene Maleimide-Based Polymers of Intrinsic Microporosity

    Directory of Open Access Journals (Sweden)

    Muntazim Munir Khan

    2015-05-01

    Full Text Available High free-volume copolymers were prepared via polycondensation with 2,3,5,6,-tetrafluoroterephthalonitrile (TFTPN in which a portion of the 3,3,3',3'-tetramethyl-1,1'-spirobisindane (TTSBI of PIM-1 was replaced with dibutyl anthracene maleimide (4bIII. An investigation of free volume using positron annihilation lifetime spectroscopy (PALS, and gas permeation measurements was carried out for the thin film composite copolymer membranes and compared to PIM-1. The average free volume hole size and the gas permeance of the copolymer membranes increased with decreasing TTSBI content in the copolymer.

  16. c-Axis correlated extended defects and critical current in YBa2Cu3Ox films grown on Au and Ag-nano dot decorated substrates

    International Nuclear Information System (INIS)

    Mikheenko, P.; Sarkar, A.; Dang, V.-S.; Tanner, J.L.; Abell, J.S.; Crisan, A.

    2009-01-01

    We report measurements of critical current in YBa 2 Cu 3 O x films deposited on SrTiO 3 substrates decorated with silver and gold nanodots. An increase in critical current in these films, in comparison with the films deposited on non-decorated substrates, has been achieved. We argue that this increase comes from the c-axis correlated extended defects formed in the films and originated from the nanodots. Additionally to creating extended defects, the nanodots pin them and prevent their exit from the sample during the film growth, thus keeping a high density of defects and providing a lower rate of decrease of the critical current with the thickness of the films. The best pinning is achieved in the samples with silver nanodots by optimising their deposition temperature. The nanodots grown at a temperature of a few hundred deg. C have a small diameter of a few nanometres and a high surface density of 10 11 -10 12 particles/cm 2 . We give evidence of c-axis correlated extended defects in YBa 2 Cu 3 O x films by planar and cross-sectional atomic force microscopy, transmission electron microscopy and angle-dependent transport measurements of critical current.

  17. Effect of electron-irradiation on the free volume of PEEK studied by positron annihilation

    International Nuclear Information System (INIS)

    Kobayashi, Y.; Haraya, K.; Hattori, S.; Sasuga, T.

    1994-01-01

    A good linear correlation was found between the size of a cavity where ortho-positronium (o-Ps) annihilates by the pick-off mechanism and the total free volume of molecular liquids and polymers. Based on the correlation, the free volume of poly(aryl ether-ether ketone) (PEEK) was evaluated as a function of electron irradiation dose and the result was compared with that obtained from gas diffusivity measurements. It was found that the effect of irradiation on the free volume of PEEK was rather small; the free volume was decreased only by a few percent (relative value) when the samples were irradiated with a dose of 50 MGy in air. ((orig.))

  18. Free-volume micro-structure of the amorphous polymers at Tg

    International Nuclear Information System (INIS)

    Bartos, J.

    1995-01-01

    The positron annihilation spectroscopy was used to the study of the free-volume microstructure of the amorphous polymers [diene-elastomers, vinyl-elastomers and thermoplastics, aromatic thermoplastics

  19. Free volumes and gas transport in polymers: amine-modified epoxy resins as a case study.

    Science.gov (United States)

    Patil, Pushkar N; Roilo, David; Brusa, Roberto S; Miotello, Antonio; Aghion, Stefano; Ferragut, Rafael; Checchetto, Riccardo

    2016-02-07

    The CO2 transport process was studied in a series of amine-modified epoxy resins having different cross-linking densities but the same chemical environment for the penetrant molecules. Positron Annihilation Lifetime Spectroscopy (PALS) was used to monitor the free volume structure of the samples and experimentally evaluate their fractional free volume fh(T) and its temperature evolution. The analysis of the free volume hole size distribution showed that all the holes have a size large enough to accommodate the penetrant molecules at temperatures T above the glass transition temperature Tg. The measured gas diffusion constants at T > Tg have been reproduced in the framework of the free volume theory of diffusion using a novel procedure based on the use of fh(T) as an input experimental parameter.

  20. Enhancing electron mobility in La-doped BaSnO3 thin films by thermal strain to annihilate extended defects

    Science.gov (United States)

    Yu, Sangbae; Yoon, Daseob; Son, Junwoo

    2016-06-01

    We report the enhancement of room-temperature electron mobility in La-doped BaSnO3 (LBSO) thin films with thermal strain induced by high temperature nitrogen (N2) annealing. Simple annealing under an N2 environment consistently doubled the electron mobility of the LBSO films on the SrTiO3 (STO) substrates to as high as 78 cm2 V-1 s-1 at a carrier concentration of 4.0 × 1020 cm-3. This enhancement is mainly attributed to annihilation of extended defects as a consequence of compressive strain induced by the difference in the thermal expansion coefficients of LBSO and STO. Our study suggests that thermal strain can be exploited to reduce extended defects and to facilitate electron transport in transparent oxide semiconductors.

  1. Resistive switching phenomena of extended defects in Nb-doped SrTiO3 under influence of external gradients

    International Nuclear Information System (INIS)

    Rodenbuecher, Christian

    2014-01-01

    gradients on the physical and chemical properties of the surface layer it is demonstrated that a transformation between a Sr-rich and a Ti-rich surface layer can be induced easily illustrating the relevance of ionic movements and phase transformations for the resistive switching effect. On the nanoscale, the switching mechanism is investigated through the use of local conductivity atomic force microscopy with atomic resolution revealing the presence of conducting clusters with a size of 20-60 nm that can be switched independently between ON and OFF states. Since distinct inhomogeneities of the donor distribution are detected by various methods, it is assumed that the conducting clusters, which can be regarded as three-dimensional extended defects, are related to Nb segregation on the nanoscale, which already evolved during the crystal growth by the Verneuil method. In order to gain an insight into the processes taking place when switching the clusters, an emulation of switching is performed on the macroscale by applying extremal electrical gradients, resulting in an evolution of a phase transformation from strontium titanate to titanium oxide in the surface layer. At the end of the thesis, a potential phenomenological model for resistive switching of SrTiO 3 :Nb based on the experimental results as well as on ab initio and finite element simulations is presented.This is done after taking into account the formation of substoichiometric titanium oxide phases, which build up a switchable bridge between the conducting clusters, thereby illustrating that the resistive switching effect in oxides is a very complex phenomenon related to many different mechanisms that need to be considered.

  2. High energy ion irradiated III-N semiconductors (AlN, GaN, InN): study of point defect and extended defect creation

    International Nuclear Information System (INIS)

    Sall, Mamour

    2013-01-01

    Nitride semiconductors III N (AlN, GaN, InN) have interesting properties for micro-and opto-electronic applications. In use, they may be subjected to different types of radiation in a wide range of energy. In AlN, initially considered insensitive to electronic excitations (Se), we have demonstrated a novel type of synergy between Se and nuclear collisions (Sn) for the creation of defects absorbing at 4.7 eV. In addition, another effect of Se is highlighted in AlN: climb of screw dislocations under the influence of Se, at high fluence. In GaN, two mechanisms can explain the creation of defects absorbing at 2.8 eV: a synergy between Se and Sn, or a creation only due to Sn but with a strong effect of the size of displacement cascades. The study, by TEM, of the effects of Se in the three materials, exhibits behaviors highly dependent on the material while they all belong to the same family with the same atomic structure. Under monoatomic ion irradiations (velocity between 0.4 and 5 MeV/u), while discontinuous tracks are observed in GaN and InN, no track is observed in AlN with the highest electronic stopping power (33 keV/nm). Only fullerene clusters produce tracks in AlN. The inelastic thermal spike model was used to calculate the energies required to produce track in AlN, GaN and InN, they are 4.2 eV/atom, 1.5 eV/atom and 0.8 eV/atom, respectively. This sensitivity difference according to Se, also occurs at high fluence. (author)

  3. Positron annihilation lifetime spectroscopy of mechanically milled protein fibre powders and their free volume aspects

    Science.gov (United States)

    Patil, K.; Sellaiyan, S.; Rajkhowa, R.; Tsuzuki, T.; Lin, T.; Smith, S. V.; Wang, X.; Uedono, A.

    2013-06-01

    The present study reports the fabrication of ultra-fine powders from animal protein fibres such as cashmere guard hair, merino wool and eri silk along with their free volume aspects. The respectively mechanically cleaned, scoured and degummed cashmere guard hair, wool and silk fibres were converted into dry powders by a process sequence: Chopping, Attritor Milling, and Spray Drying. The fabricated protein fibre powders were characterised by scanning electron microscope, particle size distribution and positron annihilation lifetime spectroscopy (PALS). The PALS results indicated that the average free volume size in protein fibres increased on their wet mechanical milling with a decrease in the corresponding intensities leading to a resultant decrease in their fractional free volumes.

  4. Chemical sensitive interfacial free volume studies of nanophase Al-rich alloys

    International Nuclear Information System (INIS)

    Lechner, W.; Puff, W.; Wuerschum, R.; Wilde, G.

    2006-01-01

    Full text: Al-based nanocrystalline alloys have attracted substantial interest due to their outstanding mechanical properties. These alloys can be obtained by crystallization of melt-spun amorphous precursors or by grain refinement upon repeated cold-rolling of elemental layers. For both synthesis routes, the nanocrystallization process is sensitively affected by interfacial chemistry and free volumes. In order to contribute to an atomistic understanding of the interfacial structure and processes during nanocrystallization, the present work deals with studies of interfacial free volumes by means of positron-annihilation-spectroscopy. In addition to positron lifetime spectroscopy which yields information on the size of free volumes, coincident Doppler broadening of the positron-electron annihilation photons is applied as novel technique for studying the chemistry of interfaces in nanophase materials on an atomistic scale. Al-rich alloys of the above mentioned synthesis routes were studied in this work. (author)

  5. Comparison of the free volume sizes and shapes determined from crystallographic and PALS data

    Directory of Open Access Journals (Sweden)

    Tydda Maciej

    2015-12-01

    Full Text Available Two different classes of molecular crystals were investigated. The first group was benzenediols, which are characterized by the same chemical composition but a different organization of their crystallographic structures; all of the compounds from this group have only one kind of free volumes. The second class was represented by olanzapine, which has more complex chemical composition and two kinds of free volumes in the structure. The o-Ps lifetime values determined from positron annihilation lifetime spectroscopy (PALS measurements agree quite well with those calculated for sizes found from crystallographic data for benzenediols (agreement within 10% of the lifetime values. For olanzapine, a good agreement is observed in the case of cuboidal free volumes, while for the other kind of void, the agreement is less satisfactory. Positronium diffusion coefficient determined from o-Ps redistribution in olanzapine agrees with these found for polymers.

  6. Comparison of Occurrence of Free Volumes for Rigid Gas Permeable and Soft Contact Lenses.

    Science.gov (United States)

    Filipecka, Katarzyna; Budaj, Mariusz; Miskowiak, Bogdan; Makowska-Janusik, Małgorzata; Filipecki, Jacek

    2015-01-01

    The polymeric materials: hydrogel, silicone--hydrogel and methacrylic acid are used in ophthalmology for the manufacture of contact lenses. It is important to research the structure of these materials, mainly the prevalence of free volumes. The study has been conducted in order to comparison the presence of free volume gaps in the structure of the polymer soft contact lenses: Etafilcon A (hydrogel), Narafilcon A (silicone-hydrogel) and the polymer rigid gas permeable (RGP) contact lens (Fluor-Silicon-Methacrylat-Copolymer). In addition, to demonstrate differences in the occurrence of free volumes between types of represented contact lenses. Three types of polymer contact lenses were used as materials: Etafilcon A, Narafilcon A and Fluor-Silicon-Methacrylat-Copolymer. The study was done by means of positron annihilation lifetime spectroscopy (PALS). As a result of the performed measurements, a graphical curve resulted which describes the relationship between the number of the annihilation acts in the time function. Significant changes were observed in the ortho-positronium long life component τ3 and their intensities between the examined polymer contact lenses. The conducted study using the Tao-Eldrup model indicates the presence of free volume holes in all research materials. There is a clear difference in the free volume sizes and their fractions between measured contact lenses are connected with oxygen permeability in these lenses. The results lead to the following connection: contact lenses of higher oxygen permeability coefficients and a water content of less, have more and larger free volumes than contact lenses of less oxygen permeability coefficient.

  7. Evaluation of the Free Volume Theory to Predict Moisture Transport and Quality Changes During Broccoli Drying

    NARCIS (Netherlands)

    Jin, X.; Sman, van der R.G.M.; Boxtel, van A.J.B.

    2011-01-01

    Moisture diffusion in porous broccoli florets and stalks is modeled using the free volume and Maxwell-Eucken theories. These theories are based on the mobility of water and concern the variation of the effective diffusion coefficient for a wide range of temperature and moisture content during

  8. Moisture Sorption Isotherms of Broccoli Interpreted with the Flory-Huggins Free Volume Theory

    NARCIS (Netherlands)

    Jin, X.; Sman, van der R.G.M.; Maanen, van J.F.C.; Deventer, van H.C.; Straten, van G.; Boom, R.M.; Boxtel, van A.J.B.

    2014-01-01

    In this work, the Flory Huggins Free Volume theory is used to interpret the sorption isotherms of broccoli from its composition and using physical properties of the components. This theory considers the mixing properties of water, biopolymers and solutes and has the potential to describe the

  9. The influences of the physical-chemical factors on the free-volume relations in polymers

    International Nuclear Information System (INIS)

    Bartos, J.; Kristiak, J.; Kristiakova, K.; Sausa, O.; Bandzuch, P.

    1995-01-01

    The positron annihilation spectroscopy was used to the study of different physical-chemical factors on the free-volume microstructure of the model polymeric systems [amorphous 1,4-cis-poly(butadiene), amorphous a-tactic and semi-crystal iso-tactic poly(propylene), polycarbonate

  10. Characterizing free volumes and layer structures in polymeric membranes using slow positron annihilation spectroscopy

    International Nuclear Information System (INIS)

    Jean, Y C; Chen Hongmin; Awad, Somia; Zhang Sui; Chen Hangzheng; Lau, Cher Hon; Wang Huan; Li Fuyun; Chung, Tai-Shung; Lee, L James; Huang, James

    2011-01-01

    Positron annihilation spectroscopy coupled with a newly built slow positron beam at National University of Singapore has been used to study the free volume, pore, and depth profile (0 - 10 μm) in cellulose acetate polymeric membrane at the bottom and top sides of membranes for ionic separation in water purification applications. The S and R parameters from Doppler broadening energy of annihilation radiation representing free volumes (0.1-1 nm size) and pores (>1 nm-μm) as a function of depth have been analyzed into multilayers, i.e. skin dense, transition, and porous layers, respectively. The top side of membrane has large free volumes and pores and the bottom side has a skin dense layer, which plays a key role in membrane performance. Positron annihilation lifetime results provide additional information about free-volume size and distribution at the atomic and molecular scale in polymeric membrane systems. Doppler broadening energy and lifetime spectroscopies coupled with a variable mono-energy slow positron beam are sensitive and novel techniques for characterization of polymeric membrane in separation applications.

  11. Numerical analysis of a main crack interactions with micro-defects/inhomogeneities using two-scale generalized/extended finite element method

    Science.gov (United States)

    Malekan, Mohammad; Barros, Felício B.

    2017-12-01

    Generalized or extended finite element method (G/XFEM) models the crack by enriching functions of partition of unity type with discontinuous functions that represent well the physical behavior of the problem. However, this enrichment functions are not available for all problem types. Thus, one can use numerically-built (global-local) enrichment functions to have a better approximate procedure. This paper investigates the effects of micro-defects/inhomogeneities on a main crack behavior by modeling the micro-defects/inhomogeneities in the local problem using a two-scale G/XFEM. The global-local enrichment functions are influenced by the micro-defects/inhomogeneities from the local problem and thus change the approximate solution of the global problem with the main crack. This approach is presented in detail by solving three different linear elastic fracture mechanics problems for different cases: two plane stress and a Reissner-Mindlin plate problems. The numerical results obtained with the two-scale G/XFEM are compared with the reference solutions from the analytical, numerical solution using standard G/XFEM method and ABAQUS as well, and from the literature.

  12. Free volume study of three types of shape memory polymers by positron annihilation

    International Nuclear Information System (INIS)

    Ujihira, Y.; Li, H.L.; Ito, K.

    1999-01-01

    Temperature dependence of nanoscopic environment of shape memory polymers such as polynorbornene (T g ∼ 313 K), polyurethane (T g ∼ 321 K = dynamic viscoelasticity, destruction of hydrogen bond ∼ 353 K) and styrene-butadiene copolymer (T m = 333 K) is observed in terms of free volume parameters - average size, numerical concentration and size distribution - estimated from positronium lifetime measurement, and mechanism of their recoveries are discussed at a molecular level. (author)

  13. Extending the scope of diagnostic chromosome analysis: detection of single gene defects using high-resolution SNP microarrays.

    Science.gov (United States)

    Bruno, Damien L; Stark, Zornitza; Amor, David J; Burgess, Trent; Butler, Kathy; Corrie, Sylvea; Francis, David; Ganesamoorthy, Devika; Hills, Louise; James, Paul A; O'Rielly, Darren; Oertel, Ralph; Savarirayan, Ravi; Prabhakara, Krishnamurthy; Salce, Nicholas; Slater, Howard R

    2011-12-01

    Microarray analysis has provided significant advances in the diagnosis of conditions resulting from submicroscopic chromosome abnormalities. It has been recommended that array testing should be a "first tier" test in the evaluation of individuals with intellectual disability, developmental delay, congenital anomalies, and autism. The availability of arrays with increasingly high probe coverage and resolution has increased the detection of decreasingly small copy number changes (CNCs) down to the intragenic or even exon level. Importantly, arrays that genotype SNPs also detect extended regions of homozygosity. We describe 14 examples of single gene disorders caused by intragenic changes from a consecutive set of 6,500 tests using high-resolution SNP microarrays. These cases illustrate the increased scope of cytogenetic testing beyond dominant chromosome rearrangements that typically contain many genes. Nine of the cases confirmed the clinical diagnosis, that is, followed a "phenotype to genotype" approach. Five were diagnosed by the laboratory analysis in the absence of a specific clinical diagnosis, that is, followed a "genotype to phenotype" approach. Two were clinically significant, incidental findings. The importance of astute clinical assessment and laboratory-clinician consultation is emphasized to optimize the value of microarrays in the diagnosis of disorders caused by single gene copy number and sequence mutations. © 2011 Wiley-Liss, Inc.

  14. Correlation of Electrical and Swelling Properties with Nano Free Volume Structure of Conductive Silicone Rubber Composites

    International Nuclear Information System (INIS)

    Abd-El Salam, M.H.; El-Gamal, S.; Abd El-Maqsoud, D.M.; Mohsen, M.

    2013-01-01

    The present study focuses on finding a correlation between the positron annihilation parameters in silicone rubber based on Poly dimethyl siloxane (PDMS) composites loaded with different conductive fillers and their swelling and electrical properties. Four types of conductive fillers have been used in this study: carbon black, graphite, copper, and nickel powders. The maximum degree of swelling Q m %, the penetration rate, P, as well as the diffusion coefficient, D, decrease with increasing the filler content due to the reduction of the size of free volume, as observed through a decrease of the probability of ortho-positronium (o-Ps) formation I 3 and the o-Ps lifetime Τ 3 , representing the size of free volume measured by the positron annihilation lifetime technique (PAL). The electrical conductivity ln (Σ) is positively correlated with the probability of free annihilation of positrons at interfaces I 2 , thus suggesting an increase in the electron density with the filler content. The activation energy of conduction, E a , is found to decrease with the increase in the loading of conductive filler and the particle size of the filler. A correlation between the free-volume V f , and the d.c. electrical conductivity ln (Σ) is found to be in accordance with Miyamoto and Shibayma model of ion conduction.

  15. Free volume study on the miscibility of PEEK/PEI blend using positron annihilation and dynamic mechanical thermal analysis

    International Nuclear Information System (INIS)

    Ramani, R; Alam, S

    2015-01-01

    High performance polymer blend of poly(ether ether ketone) (PEEK) and poly(ether imide) (PEI) was examined for their free volume behaviour using positron annihilation lifetime spectroscopy and dynamic mechanical thermal analysis methods. The fractional free volume obtained from PALS shows a negative deviation from linear additivity rule implying good miscibility between PEEK and PEI. The dynamic modulus and loss tangent were obtained for the blends at three different frequencies 1, 10 and 100 Hz at temperatures close to and above their glass transition temperature. Applying Time-Temperature-Superposition (TTS) principle to the DMTA results, master curves were obtained at a reference temperature T o and the WLF coefficients c 0 1 and c 0 2 were evaluated. Both the methods give similar results for the dependence of fractional free volume on PEI content in this blend. The results reveal that free volume plays an important role in determining the visco-elastic properties in miscible polymer blends. (paper)

  16. Free volume evolution in 50 MeV Li3+ ion-irradiated polymers studied by positron annihilation lifetime spectroscopy

    Science.gov (United States)

    Singh, Paramjit; Kumar, Rajesh; Prasad, Rajendra

    2013-02-01

    This article is aimed at studying the effect of ion irradiation on free volume of polyethersulphone (PES) and polyamide nylon-6 (PN-6) polymers by positron annihilation lifetime spectroscopy (PALS). Free volume properties of polymeric materials change with swift heavy ion irradiation. Free volume is found to have a strong correlation with the macroscopic properties of the polymer. PALS has recently emerged as a unique non-destructive and non-interfering nano-probe, capable of measuring the free volume hole size in polymers with high detection efficiency. PES and PN-6 polymer films of thickness of 250 μm were irradiated with Li3+ ions of energy 50 MeV from the 15 UD Pelletron accelerator at the Inter University Accelerator Centre, New Delhi, India. PES films were irradiated to the fluences of 1011, 1012, 1013 and 1014 ions/cm2, whereas PN-6 films were irradiated to the fluences of 1011, 1012 and 1013 ions/cm2. The average free volume and fractional free volume obtained from the long-lived component, attributed to ortho-positronium lifetime, are found to vary with the variation of fluence in both the cases.

  17. Dynamics study of free volume properties of SMA/SMMA blends by PAL method

    International Nuclear Information System (INIS)

    Jiang, Z.Y.; Jiang, X.Q.; Huang, Y.J.; Lin, J.; Li, S.M.; Li, S.Z.; Hsia, Y.F.

    2006-01-01

    Miscibility of poly(styrene-co-maleic anhydride) (containing 7 wt% maleic anhydride)/poly(styrene-co-methyl methacrylate) (containing 40 wt% styrene) blends were previously studied. It was obtained that SMA70 (containing 70 wt% of SMA in SMA/SMMA blends) is miscible in molecular level but SMA20 is not. In this paper, the two blends selected were used to investigate the temperature dependence of free volume parameters. It showed there are different deviations of free volume parameters in SMA20 and SMA70, and it was interesting that temperature dependence of ortho-positronium lifetime τ 3 of the SMA20 mixture exhibits two breaks in the range temperature from 90 deg. C to 120 deg. C, which revealed that the mixture has two glass transition ranges. Also, ortho-positronium lifetime τ 3 of the SMA20 mixture is nearly constant in the temperature range from 130 deg. C to 160 deg. C. These indicated that SMA20 blend is phase-separated in room temperature and become miscible above 130 deg. C, which may be due to steric hindrance effect of phenyl rings of SMMA and SMA. From the deviation of o-Ps lifetimes of SMA70, the single glass transition temperature of SMA70 blend was shown. Combining the previous study, it was further concluded that PAL method seems to be a powerful method to detect in situ phase behavior of immiscible polymer blends and glass transition of miscible polymer blends

  18. Dendrimeric Thin-Film Composite Membranes: Free Volume, Roughness, and Fouling Resistance

    KAUST Repository

    Phuoc, Duong

    2017-11-10

    Copolyamide films with a thickness from 50 to 780 nm were fabricated by interfacial polymerization between mixtures of m-phenylene diamine and primary amine-terminated polyamidoamine dendrimers (PAMAM) in the aqueous phase and trimesoyl chloride (TMC) in the organic phase. Different PAMAM generations (G0, d = 15 Å, Z = 4; G3, d = 36 Å, Z = 32; and G5, d = 54, Z = 128, where d is the measured diameter and Z is the number of terminal groups) and concentrations were used to obtain copolyamide films with different crosslinked structures. The influences of the concentration and degree of branching (PAMAM generation) on free volume were analysed via positon annihilation spectroscopy (PAS) and correlated with the separation properties of copolyamide films. Besides, surface and intrinsic properties of copolyamide films under different conditions were compared. The high hydrophilicity of PAMAM in the copolyamide network leads to the formation of a hydration layer on the copolyamide surface, which minimizes fouling. The separation performance of copolyamide membranes with various PAMAM networks was investigated in forward osmosis (FO) experiments. Understanding the correlation between the PAMAM structure/concentration, free volume, thickness, and surface intrinsic properties leads to the design of suitable fouling resistant thin-film composite membranes in a single interfacial polymerization process.

  19. Internal stress and defect-related free volume in submicrocrystalline Ni studied by neutron diffraction and difference dilatometry.

    Science.gov (United States)

    Kotzurek, J A; Hofmann, M; Simic, S; Pölt, P; Hohenwarter, A; Pippan, R; Sprengel, W; Würschum, R

    2017-01-01

    A combined study of neutron diffraction and difference dilatometry on submicrocrystalline Ni prepared by high pressure torsion aims at studying the anisotropic behaviour during dilatometry and its relation to internal stress and structural anisotropy. Macroscopic stresses were undetectable in the dilatometer samples. Along with specific tests such as post cold-rolling, this shows that an observed anisotropic length change upon annealing is not caused by internal stress, but can be explained by the inherent microstructure, i.e. the anisotropic annealing of relaxed vacancies at grain boundaries of shape-anisotropic crystallites.

  20. Classical and recent free-volume models for polymer solutions: A comparative evaluation

    DEFF Research Database (Denmark)

    Radfarnia, H.R.; Kontogeorgis, Georgios; Ghotbi, C.

    2007-01-01

    In this work, two "classical" (UNIFAC-FV, Entropic-FV) and two "recent" free-volume (FV) models (Kannan-FV, Freed-FV) are comparatively evaluated for polymer-solvent vapor-liquid equilibria including both aqueous and non-aqueous solutions. Moreover, some further developments are presented here...... by the modified Freed-FV model for athermal and non-athermal polymer systems are compared to other "recent" and "classical" FV models, indicating an improvement for the modified Freed-FV model for aqueous polymer solutions. Second, for the original Freed-FV model, new UNIFAC group energy parameters are regressed...... to using the classical UNIFAC parameters, for VLE of aqueous and alcohol polymer systems....

  1. Comparison of the enthalpy recovery and free volume of polyvinylpyrrolidone during anomalous glassy to rubbery transition.

    Science.gov (United States)

    Zelkó, Romána; Süvegh, Károly

    2004-03-01

    Previous studies confirmed that along with the structural changes of the amorphous binder, that of the polyvinylpyrrolidone, the tensile strength and consequently, the dissolution behaviour of its tablets changed significantly during the storage period. Structural formation during the glassy to rubbery transition of polyvinylpyrrolidone was followed by the changes in the free volume and enthalpy recovery values of the polymer. The results suggest that the apparent structure formation of water and polymer under glassy to rubbery transition is interrelated in a dynamic and complex manner which can be tracked by the combination of enthalpy recovery studies and positron lifetime measurements. Positron lifetime measurements more sensitively react to the structural rearrangements than enthalpy recovery, thus it can be recommended as a sensitive tool for stability tests during the formulation phase of drug development.

  2. The temperature and pressure dependence of the free volume in fluoroelastomers from PALS and PVT experiments

    International Nuclear Information System (INIS)

    Dlubek, G.; Sen Gupta, A.; Wawryszczuk, J.

    2005-01-01

    Positron lifetime and pressure-volume-temperature experiments were performed as function of T (100-485 K) and P (10 -5 Pa - 500 MPa) on a fluoroelastomer. From positron annihilation lifetime spectroscopy, analyzed with LT9.0 assuming the dispersion in the e + (τ 2 ) and o-Ps(τ 3 ) lifetime, the mean (υ h ), and the width (standard deviation), σ h , of the hole size distribution were calculated. The pressure-volume-temperature data were analyzed using the Simba-Somcynsky hole-lattice theory to estimate the specific hole free volume V f . From comparison of V f with (υ h ) the specific hole number, N' h is estimated. The data from thermal expansion and pressure experiments show complete agreement with taking into account the compressibility of the occupied volume. (author)

  3. The Temperature and Pressure Dependence of the Free Volume in Fluoroelastomers from PALS and PVT Experiments

    Science.gov (United States)

    Dlubek, G.; Gupta, A. Sen; Wawryszczuk, J.; Kilburn, D.; Pionteck, J.; Krause-Rehberg, R.; Goworek, T.; Alam, M. A.; Kaspar, H.; Lochhaas, K. H.

    2005-04-01

    Positron lifetime and pressure-volume-temperature experiments were performed as function of T (100-485 K) and P (10-5 Pa-500 MPa) on a fluoroelastomer. From positron annihilation lifetime spectroscopy, analyzed with LT9.0 assuming a dispersion in the e+ (τ2) and o-Ps (τ3) lifetime, the mean,, and the width (standard deviation),σh, of the hole size distribution were calculated. The pressure-volume-temperature data were analyzed using the Simha-Somcynsky hole-lattice theory to estimate the specific hole free volume Vf. From a comparison of Vf with the specific hole number, N'h, is estimated. The data from thermal expansion and pressure experiments show complete agreement when taking into account the compressibility of the occupied volume.

  4. External field effects on diffusion and solidification derived from the free-volume model

    Science.gov (United States)

    Miller, R. I.; Ruff, R. C.

    1975-01-01

    Expressions for the diffusion coefficient and the solidification rate from the free-volume model of liquids developed by Turnbull and Cohen have been used to estimate the effects which microgravity and magnetic fields will have on these quantities. The mathematical formalism describing changes of the diffusion coefficient and the solidification rate is the same for both the microgravity and magnetic field cases, but the difference between the magnitudes of the two effects is quite large. The change in the two parameters is found to be less than .0001% for the microgravity case and on the order of 0.1 to 1.1% for the magnetic field case for four representative materials. The diffusion coefficient and the solidification rate are found to increase under the influence of an applied magnetic field, and this is in agreement with experimental observations.

  5. Positronium atom in solids. Peculiarities of formation and interconnection with free volume nanostructure

    International Nuclear Information System (INIS)

    Shantarovich, V.P.

    2006-01-01

    The recent several decades have seen the spectacular advances in a new area at the junction of elementary particle physics and chemistry, the so called chemistry of new atoms in which either electron is replaced by another negative particle or a proton by another positive particle. The area of research does not confine itself to chemical studies alone. External influences on the properties of new atoms provide useful, sometimes unique information about the structure of solids. In this review, we survey briefly properties of the new atoms and illustrate the last statement on example of positronium, the simplest hydrogen-like atom, where pick-off annihilation process gives valuable information of the free volume nanostructure of solids. (author)

  6. Free volume dependence on electrical properties of Poly (styrene co-acrylonitrile)/Nickel oxide polymer nanocomposites

    Science.gov (United States)

    Ningaraju, S.; Hegde, Vinayakaprasanna N.; Prakash, A. P. Gnana; Ravikumar, H. B.

    2018-04-01

    Polymer nanocomposites of Poly (styrene co-acrylonitrile)/Nickel Oxide (PSAN/NiO) have been prepared. The increased free volume sizes up to 0.4 wt% of NiO loading indicates overall reduction in packing density of polymer network. The decreased o-Ps lifetime (τ3) at higher concentration of NiO indicates improved interfacial interaction between the surface of NiO nanoparticles and side chain of PSAN polymer matrix. The increased AC/DC conductivity at lower wt% of NiO loading demonstrates increased number of electric charge carriers/mobile ions and their mobility. The increased dielectric constant and dielectric loss up to 0.4 wt% of NiO loading suggests the increased dipoles polarization.

  7. Free volume model for the unexpected effect of C2-methylation on the properties of imidazolium ionic liquids.

    Science.gov (United States)

    Chen, Zheng Jian; Lee, Jong-Min

    2014-03-13

    For 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides and their cationic C2-methylated isomers, that is, [C(n)MIm]NTf2 and [C(n-1)DMIm]NTf2 (n = 3-8), the latter always has much higher viscosities (∼1.66 times at 25 °C) than the former. This finding is unexpected and contrary to the loss of the predominant hydrogen bonding between the cation and anion, caused by the C2-methylation in the imidazolium ionic liquids. In the present study, we propose a free volume model to explain this mysterious phenomenon. For the isomeric pairs, [C(n-1)DMIm]NTf2 was found to possess less unoccupied (free) volume than [C(n)MIm]NTf2 by ∼4.5 mL mol(-1) determined by both Fürth's surface tension and molar volume methods, and the free volume difference can be quantitatively correlated with the C2-methylation effect on viscosity. Generally, the less free volume in [C(n-1)DMIm]NTf2 relative to [C(n)MIm]NTf2 reduces the number of the hole carriers for molecular transport with a resulting increase in viscosity. Besides, the free volume model can also be applied to account for the C2-methylation effect on other properties, such as conductivity, surface tension, density, and refractive index.

  8. Free-volume structure of fluoropolymer-based radiation-grafted electrolyte membranes investigated by positron annihilation lifetime spectroscopy

    International Nuclear Information System (INIS)

    Sawada, S; Maekawa, Y; Kawasuso, A; Maekawa, M; Yabuuchi, A

    2010-01-01

    In the field of polymer-electrolyte-membrane (PEM) fuel cell technology, the structures of free-volume holes in the PEMs are very important because they are correlated to the supplied-gas crossover phenomenon, which sometimes deteriorates the cell performance. In this study, we investigated the size and location of free-volume holes in the crosslinked-polytetrafluoroethylene (cPTFE) based radiation-grafted PEMs by positron annihilation lifetime (PAL) spectroscopy. For comparison, the base cPTFE and polystyrene grafted films were also measured. From the analysis of PAL spectra, it was found that there were free-volume holes with different radius of 0.28-0.30 nm and 0.44-0.45 nm. The smaller holes should be located in both PTFE crystallites and poly(styrene sulfonic acid) grafts, while the larger holes are considered to exist in amorphous PTFE phases.

  9. Point defects and atomic transport in crystals

    International Nuclear Information System (INIS)

    Lidiard, A.B.

    1981-02-01

    There are two principle aspects to the theory of atomic transport in crystals as caused by the action of point defects, namely (1) the calculation of relevant properties of the point defects (energies and other thermodynamic characteristics of the different possible defects, activation energies and other mobility parameters) and (2) the statistical mechanics of assemblies of defects, both equilibrium and non-equilibrium assemblies. In the five lectures given here both these aspects are touched on. The first two lectures are concerned with the calculation of relevant point defect properties, particularly in ionic crystals. The first lecture is more general, the second is concerned particularly with some recent calculations of the free volumes of formation of defects in various ionic solids; these solve a rather long-standing problem in this area. The remaining three lectures are concerned with the kinetic theory of defects mainly in relaxation, drift and diffusion situations

  10. Detection of atomic scale changes in the free volume void size of three-dimensional colorectal cancer cell culture using positron annihilation lifetime spectroscopy.

    Science.gov (United States)

    Axpe, Eneko; Lopez-Euba, Tamara; Castellanos-Rubio, Ainara; Merida, David; Garcia, Jose Angel; Plaza-Izurieta, Leticia; Fernandez-Jimenez, Nora; Plazaola, Fernando; Bilbao, Jose Ramon

    2014-01-01

    Positron annihilation lifetime spectroscopy (PALS) provides a direct measurement of the free volume void sizes in polymers and biological systems. This free volume is critical in explaining and understanding physical and mechanical properties of polymers. Moreover, PALS has been recently proposed as a potential tool in detecting cancer at early stages, probing the differences in the subnanometer scale free volume voids between cancerous/healthy skin samples of the same patient. Despite several investigations on free volume in complex cancerous tissues, no positron annihilation studies of living cancer cell cultures have been reported. We demonstrate that PALS can be applied to the study in human living 3D cell cultures. The technique is also capable to detect atomic scale changes in the size of the free volume voids due to the biological responses to TGF-β. PALS may be developed to characterize the effect of different culture conditions in the free volume voids of cells grown in vitro.

  11. Detection of Atomic Scale Changes in the Free Volume Void Size of Three-Dimensional Colorectal Cancer Cell Culture Using Positron Annihilation Lifetime Spectroscopy

    Science.gov (United States)

    Castellanos-Rubio, Ainara; Merida, David; Garcia, Jose Angel; Plaza-Izurieta, Leticia; Fernandez-Jimenez, Nora; Plazaola, Fernando; Bilbao, Jose Ramon

    2014-01-01

    Positron annihilation lifetime spectroscopy (PALS) provides a direct measurement of the free volume void sizes in polymers and biological systems. This free volume is critical in explaining and understanding physical and mechanical properties of polymers. Moreover, PALS has been recently proposed as a potential tool in detecting cancer at early stages, probing the differences in the subnanometer scale free volume voids between cancerous/healthy skin samples of the same patient. Despite several investigations on free volume in complex cancerous tissues, no positron annihilation studies of living cancer cell cultures have been reported. We demonstrate that PALS can be applied to the study in human living 3D cell cultures. The technique is also capable to detect atomic scale changes in the size of the free volume voids due to the biological responses to TGF-β. PALS may be developed to characterize the effect of different culture conditions in the free volume voids of cells grown in vitro. PMID:24392097

  12. Positron lifetime studies of the dose dependence of nanohole free volumes in ion-irradiated conducting poly-(ethylene-oxide)-salt polymers

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rajesh [Department of Applied Physics, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh 202 002 (India); De, Udayan [Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata 700 064 (India); Nambissan, P.M.G. [Saha Institute of Nuclear Physics, 1/AF, Bidhan Nagar, Kolkata 700 064 (India); Maitra, M. [CMPR Centre, Department of Physics, Jadavpur University, Kolkata 700 032 (India); Ali, S. Asad [Department of Applied Physics, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh 202 002 (India); Middya, T.R.; Tarafdar, S. [CMPR Centre, Department of Physics, Jadavpur University, Kolkata 700 032 (India); Singh, F.; Avasthi, D.K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Prasad, Rajendra [Department of Applied Physics, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh 202 002 (India)], E-mail: rajendraprasad1@rediffmail.com

    2008-04-15

    Polymer based ion conducting materials have potential applications as an electrolyte and separator in the field of lithium batteries. Solid polymer electrolytes for lithium batteries are one of the best applications. The irradiation of polymeric materials with swift heavy ions results into the change of their free volume properties which have strong correlation with their macroscopic properties. Poly-ethylene-oxide (PEO)-salt polymers were prepared using solution-cast method. Irradiation of the films with 95 MeV oxygen (O{sup 6+}) ions from the pelletron accelerator at IUAC, New Delhi, India, to different fluences up to 10{sup 13} ions/cm{sup 2} was carried out under high vacuum of the order of 4 x 10{sup -6} Torr. Nanosized free volume parameters in PEO-salt polymer complex have been studied by positron annihilation lifetime spectroscopy (PALS) and Doppler broadening spectroscopy (DBS). From orthopositronium (o-Ps) lifetime, free volume hole radius, free volume of micro voids and fractional free volume are computed. Free volume changes with the fluence are studied. The variation of o-Ps lifetime, mean free volume and fractional free volume with the ion fluence is studied. o-Ps lifetime, free volume radius, mean free volume and fractional free volume decrease for the fluence 10{sup 10} and 10{sup 11} ions/cm{sup 2} and then increase with fluences of 10{sup 12} and 10{sup 13} ions/cm{sup 2}. The S parameter showed a continuous decrease with increasing fluence of irradiation. The intermediate lifetime {tau}{sub 2} also showed a similar decrease. These results indicate the occurrence of scission in the polymer chains and the fragmentation of larger free volumes into smaller ones.

  13. A free-volume modification of GEM-QC to correlate VLE and LLE in polymer solutions

    International Nuclear Information System (INIS)

    Radfarnia, H.R.; Taghikhani, V.; Ghotbi, C.; Khoshkbarchi, M.K.

    2004-01-01

    The generalized quasi-chemical (GEM-QC) model proposed by Wang and Vera is modified to correlate better the phase equilibrium and to overcome the shortcoming of the original model to predict the lower critical solution temperature (LCST) of binary polymer solutions. This shortcoming is mainly because the GEM-QC model does not consider the effect of free-volume, which is important in systems containing molecules with large size differences. The proposed modification is based on replacing the combinatorial term of the GEM-QC model by a term proposed by Kontogerogis et al., which includes the effect of the free-volume. The main advantage of the free volume generalized quasi-chemical (GEM-QC-FV) model over the original GEM-QC is its ability to predict the phase behaviour of binary polymer solutions with LCST behaviour. In addition, the free volume UNIQUAC (UNIQUAC-FV) model is used to correlate VLE and LLE experimental data for binary polymer solutions. The comparison of the results obtained from the GEM-QC-FV model and the UNIQUAC-FV model shows the superiority of the GEM-QC-FV model in correlating the VLE and LLE experimental data for binary polymer solutions

  14. Simultaneous free-volume modeling of the self-diffusion coefficient and dynamic viscosity at high pressure

    DEFF Research Database (Denmark)

    Boned, C.; Allal, A.; Baylaucq, A.

    2004-01-01

    In this work, a simultaneous modeling of the self-diffusion coefficient and the dynamic viscosity is presented. In the microstructural theory these two quantities are governed by the same friction coefficient related to the mobility of the molecule. A recent free-volume model, already successfully...

  15. Prediction of the state diagram of starch water mixtures using the Flory--Huggins free volume theory

    NARCIS (Netherlands)

    Sman, van der R.G.M.; Meinders, M.B.J.

    2011-01-01

    In this paper we analyse the phase and state transitions of starch and other glucose homopolymers and oligomers using the free volume extension of the Flory–Huggins theory by Vrentas and Vrentas, combined with the Couchman–Karasz theory for the glass transition. Using scaling relations of model

  16. The Effect of Temperature on the Free Volume in Polytetrafluoroethylene Studied by Positron Annihilation Spectroscopy

    International Nuclear Information System (INIS)

    Abdel-Latif, R.M.; Mohamed, H.F.M.; Abdel-Hady, E.E.; Mohamed, S.S.

    2005-01-01

    The positron annihilation techniques have been applied to investigate the free volume holes in pure and doped polytetrafluoroethylene (PTFE) with glass as a function of temperature. The measurements were performed from room temperature up to 250 degree C. The lifetime spectra were analyzed using two methods; 1) Finite-term analysis to determine the average values of the orthopositronium (o-Ps) lifetime and its intensity using PATFIT program, 2) Continuous lifetime analysis to obtain the o-Ps lifetime and o-Ps hole volume distributions using MELT program. The ortho-positronium (o-Ps) lifetimes, (T3 and T4) are found to be vary depending upon the phase of the polymer. Within the temperature range two transitions can be observed. The first one is related to the glass transition temperature, T g (at 130 degree C for pure PTFE and at 110 degree C for doped PTFE with glass). The second one is the crystalline temperature at 210 degree C for the two samples. It was found that, T g is shifted toward the lower values (110 degree C) for doped PTFE with glass, which could be attributed to the increase in the degree of crystallinity. This is in consistent with the wide-angle x-ray scattering data. A correlation between the positron annihilation parameters and the electrical conductivity was achieved

  17. Positron Lifetime as a Nano probe for Free Volume in Microbial Poly(3- Hydroxybutyrate/ Polymethylmethacrylate) Blends

    International Nuclear Information System (INIS)

    Abdel-Hady, E.E.; Abdel-El-Latif, R.M.; Mohamed, S.S.

    2009-01-01

    Poly(β-hydroxybutyrate) PHB is a bio technologically produced polyesters, highly crystalline, totally biodegradable with low versatility in mechanical properties. To overcome this problem it is performed a reactive blending producer with a glassy acrylic polymer, Poly(methylmethacrylate) (PMMA) with different concentrations. positron annihilation lifetime (PAL) spectroscopy has been used to study the effect of PMMA concentrations on the free volume hole properties of PHB. PAL spectra were analyzed using PALSF it program into three components which reflected three different morphologies of the polymer structure. The ortho positronium (ο-Ps) parameters revealed an inflection at (75/25 wt/wt) PHB/PMMA blend. Pure PHB and (75/25 wt/wt) PHB/PMMA blend have been measured as a function of temperature from -30 degree C to 90 degree C. The data clearly revealed the glass transition temperature (T g ) at zero degree C. An attempt is done to find a correlation between the electrical properties of PHB with different concentrations of PMMA and the positron annihilation parameters.

  18. Glass Transition Temperature of Saccharide Aqueous Solutions Estimated with the Free Volume/Percolation Model.

    Science.gov (United States)

    Constantin, Julian Gelman; Schneider, Matthias; Corti, Horacio R

    2016-06-09

    The glass transition temperature of trehalose, sucrose, glucose, and fructose aqueous solutions has been predicted as a function of the water content by using the free volume/percolation model (FVPM). This model only requires the molar volume of water in the liquid and supercooled regimes, the molar volumes of the hypothetical pure liquid sugars at temperatures below their pure glass transition temperatures, and the molar volumes of the mixtures at the glass transition temperature. The model is simplified by assuming that the excess thermal expansion coefficient is negligible for saccharide-water mixtures, and this ideal FVPM becomes identical to the Gordon-Taylor model. It was found that the behavior of the water molar volume in trehalose-water mixtures at low temperatures can be obtained by assuming that the FVPM holds for this mixture. The temperature dependence of the water molar volume in the supercooled region of interest seems to be compatible with the recent hypothesis on the existence of two structure of liquid water, being the high density liquid water the state of water in the sugar solutions. The idealized FVPM describes the measured glass transition temperature of sucrose, glucose, and fructose aqueous solutions, with much better accuracy than both the Gordon-Taylor model based on an empirical kGT constant dependent on the saccharide glass transition temperature and the Couchman-Karasz model using experimental heat capacity changes of the components at the glass transition temperature. Thus, FVPM seems to be an excellent tool to predict the glass transition temperature of other aqueous saccharides and polyols solutions by resorting to volumetric information easily available.

  19. Polymer Mixtures and Films: Free Volume as a Driving Force for Miscibility and Glassiness

    Science.gov (United States)

    DeFelice, Jeffrey

    The microscopic characteristics of polymer molecules are connected with many macro- scopic and mechanical properties of their liquid (pure or mixed) and solid states. How these properties are affected by the different molecular attributes of polymers is of particular interest for practical applications of polymer materials. In Part I of this thesis, the thermodynamics of polymer/supercritical CO2 mixtures and blends of linear and branched polymers are modeled using a lattice based equation of state approach. Analyses of trends in the pure component physical properties lead to insight regarding how changes in molecular architecture and/or isotopic labeling affect the relative compatibilities of the mixtures. This approach is also applied to the mixed state to predict the enthalpic and entropic changes of mixing, from which, information is provided about the role of pure component properties in controlling the underlying thermodynamics of the mixtures. In Part II, the focus of this thesis turns to how interfacial effects can shift a number of physical properties in glass forming fluids relative to those of the pure bulk material. One of the most notable deviations from bulk behavior that has been reported for these systems is a change in the glass transition temperature (Tg). In this work, interfacial effects on Tg are probed in film and polymer/additive systems using a simple kinetic lattice model that simulates free volume and mobility in glass forming fluids. For films, the thickness-dependent behavior of Tg is characterized for different types of interfaces, including films that are substrate supported, free- standing, and 'stacked'. Connections are drawn between the size of the region of enhanced mobility near a free surface and the distribution of local Tg values across a film. For polymer/additive systems, where the "interface" is dispersed throughout the material, trends in additive induced Tg changes are analyzed with respect to additive concentration and

  20. Crosslinking and stabilization of high free volume polymers for gas separations

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Lei

    2008-07-01

    Poly(1-trimethylsilyl-l-propyne) [PTMSP] and poly(4-methyl-2-pentyne) [PMP] are high free volume, amorphous, glassy polymers. They have high gas permeability coefficients. However, their selectivities for gas separations are relatively low, and the high gas permeabilities have been reported to be unstable over time because of physical aging. This behavior results primarily from a decrease in the non-equilibrium excess free volume of PTMSP and PMP. In order to stabilize the permeability of PTMSP and PMP, as well as improve their physical and chemical stability, they were crosslinked with bis(aryl azide)s by photo irradiation and/or thermal treatment. Crosslinked PMP and PTMSP have shown increased chemical and physical stability. Crosslinked PMP and PTMSP membranes are insoluble in their common solvents; the gas permeability coefficients of the crosslinked membranes are almost constant over time. The process is simple and effective, and thus PMP and PTMSP can be easily converted to mechanically stable membranes. Permeability coefficients in PMP and PTMSP increase systematically with the addition of nano scale non porous inorganic filler particles, such as fumed silica (FS) and titanium dioxide (Ti02). This result is in contrast to the results of the traditional filled systems where the presence of impermeable particles yields a more tortuous diffusion path and reduces permeability coefficient. Gas solubility coefficients in PMP and PTMSP are essentially unaffected by the presence of nanoparticles at up to 35 wt%. Penetrant diffusion coefficients in PMP and PTMSP increase regularly with increasing nanoparticles content, and it is this rise in diffusivity that is responsible for the elevated permeability in the nano composites. The enhancement in permeability obtained for a given filler loading increases as the primary particle size of the filler decreases. This result is likely related to the smaller particles yielding larger polymer/particle interfacial area, since

  1. The influence of Metolose structure on the free volume and the consequent metoprolol tartrate release of patches.

    Science.gov (United States)

    Papp, József; Marton, Sylvia; Süvegh, Károly; Zelkó, Romána

    2009-01-01

    Matrix-type patches containing Metoprolol tartrate were prepared from two types of Metolose and acrylate polymers. Metolose SM 4000 and Metolose 90SH 100.000SR were applied in different proportions in the patches where the total polymer content was kept constant in each sample. The purpose of the study was to investigate the effect of Metolose structure on the free volume of the patches and the consequent drug release profile. The drug release profiles were characterized by zero-order and first-order models. The results indicate that Metolose, containing hydroxypropyl ether groups and methyl ether groups, enables the formation of H-bonds, thus increasing the free volume holes and the consequent extent and rate of drug release of patches.

  2. Free volume of mixed cation borosilicate glass sealants elucidated by positron annihilation lifetime spectroscopy and its correlation with glass properties

    Science.gov (United States)

    Ojha, Prasanta K.; Rath, Sangram K.; Sharma, Sandeep K.; Sudarshan, Kathi; Pujari, Pradeep K.; Chongdar, Tapas K.; Gokhale, Nitin M.

    2015-01-01

    The role of La+3/Sr+2 ratios, which is varied from 0.08 to 5.09, on density, molar volume, packing fraction, free volume, thermal and electrical properties in strontium lanthanum aluminoborosilicate based glass sealants intended for solid oxide fuel cell (SOFC) applications is evaluated. The studies reveal expansion of the glass network evident from increasing molar volume and decreasing packing fraction of glasses with progressive La+3 substitutions. The molecular origin of these macroscopic structural features can be accounted for by the free volume parameters measured from positron annihilation lifetime spectroscopy (PALS). The La+3 induced expanded glass networks show increased number of subnanoscopic voids with larger sizes, as revealed from the ortho-positronium (o-Ps) lifetime and its intensity. A remarkably direct correspondence between the molar volume and fractional free volume trend is established with progressive La2O3 substitution in the glasses. The effect of these structural changes on the glass transition temperature, softening temperature, coefficient of thermal expansion, thermal stability as well as electrical conductivity has been studied.

  3. Dependence of alpha particle track diameter on the free volume holes size using positron annihilation lifetime technique

    Energy Technology Data Exchange (ETDEWEB)

    El-Gamal, S. [Physics Department, Faculty of Education, Ain Shams University, Roxy, 11711 Cairo (Egypt); Abdalla, Ayman M., E-mail: aymanabdalla62@hotmail.com [Physics Department, Faculty of Arts and Sciences, Najran University, Najran (Saudi Arabia); Centre for Advanced Materials and Nano-Engineering, Najran University, Najran 11001 (Saudi Arabia); Abdel-Hady, E.E. [Physics Department, Faculty of Science, Minia University, BO 61519, Minia (Egypt)

    2015-09-15

    The alpha particle track diameter dependence of the free volume holes size (V{sub f}) in DAM–ADC and CR-39 nuclear track detectors was investigated using positron annihilation lifetime technique. The effect of temperature on the alpha particle track diameter and free volume were also investigated in the T-range (RT-130 °C). The obtained results revealed that the values of ortho-positronium lifetime τ{sub 3} and V{sub f} increases while I{sub 3} slightly increases as T increases for the two detectors. The values of τ{sub 3}, V{sub f} and I{sub 3} are higher in CR-39 than DAM–ADC. The interpretation of obtained results is based on the fact that increasing T leads to significant enhancement of thermal expansion of the polymer matrix and consequently V{sub f} increases. The track diameter increases as T increases. This can be explained by the fact that the increase in T increases the crystal size and V{sub f} in the polymer. A relationship between V{sub f} and the alpha particle track diameter was obtained. Moreover results of detector irradiation, along with free volume evaluation are addressed and thoroughly discussed.

  4. Poly(p-Phenylene Sulfonic Acids). PEMs with frozen-in free volume

    Energy Technology Data Exchange (ETDEWEB)

    Litt, Morton [Case Western Reserve Univ., Cleveland, OH (United States)

    2016-01-21

    Early work with rigid rod aromatic polyelectrolytes implied that steric hindrance in packing of the rigid rods left unoccupied volumes that could absorb and hold water molecules strongly. We called this “frozen in free volume). It is illustrated and contrasted with the packing of flexible backbone polyelectrolytes (Reference 5 of this report). This was quantified for poly(biphenylene disulfonic acid) (PBDSA) and poly(phenylene disulfonic acid) (PPDSA). We found that PPDSA held three water molecules per acid group down to 11% relative humidity (RH) and had very high conductivity even at these low RHs. (Reference 1 of report.) The frozen-in free volume was calculated to be equivalent to a λ of 3.5. The work reported below concentrated on studying these polymers and their copolymers with biphenylene disulfonic acid. As expected, the polyelectrolytes are water soluble. Several approaches towards making water stable films were studied. Grafting alkyl benzene substituents on sulfonic acid groups had worked for PBPDSA (1) so it was tried with PPDSA and a 20%/80% copolymer of BPDSA and PDSA (B20P80). T-butyl, n-octyl and n-dodecyl benzene were grafted. Good films could be made. Water absorption and conductivity were studied as a function of RH and temperature (Reference 2). When less than 20% of the sulfonic acid groups were grafted, conductivity was much higher than that of Nafion NR212 at all RHs. At low graft levels, conductivity was ten times higher. Mechanical properties and swelling were acceptable below 90% RH. However, all the films were unstable in water and slowly disintegrated. The proposed explanation was that the molecules formed nano-aggregates in solution held together by hydrophobic bonding. Their cast films disintegrated when placed in water since hydrophobic bonding between the nano-aggregates was poor. We then shifted to crosslinking as a method to produce water stable films (References 3 and 4). Biphenyl could easily be reacted with the polymer

  5. A study on microstructures and extended defects in Ni- and Co-base superalloys. Development and application of advanced TEM techniques

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Julian

    2016-04-21

    To improve the efficiency of stationary gas turbines and air craft jet engines, it is crucial to increase the maximum temperature capabilities of single crystalline superalloys by appropriate alloy design and microstructure tuning. The mechanical properties of superalloys are largely influenced by the physical constitution of the microstructure. To develop a better understanding of fundamental aspects of creep deformation, like the stress states, defect structures and other degradation processes, it is necessary to employ scale-bridging characterization. In the present work, Ni- and Co-based superalloys are investigated by a series of advanced transmission electron microscopy techniques and by the application of specifically developed characterization methods to identify dominating processes on atomic scale and hence to make a direct correlation to the macroscopic creep behavior. For instance, the misfit between γ and γ' in the initial microstructure is of great importance, since it strongly influences the rafting process and the interfacial dislocation network. To address the stress state, on the one hand misfit measurements in undeformed samples are conducted and are directly compared to finite-element simulations. On the other hand, deformed samples are investigated to assess the influence of an initial rafting process and the formation of an interface dislocation network. For this, characterization methods are used which are based on the evaluation of atomically resolved images and on electron diffraction. Moreover, the temperature dependency of the misfit and of the microstructure stability is specifically investigated for different Co-base alloys in in situ heating experiments. The characterization of defect structures in Ni-base superalloys after creep deformation builds the second pillar of this work. Specific cutting processes of superdislocations are studied to elucidate which atomic processes take place. A series of left angle 100 right angle and

  6. The local free volume and its correlation with the structural, chemical and dynamic properties of branched polymers, polymer electrolytes, highly oriented polyethylene fibres and other polymers

    CERN Document Server

    Bamford, D

    2002-01-01

    The work described in this thesis is concerned with the study of the local free volume measured by Positron Annihilation Spectroscopy and its correlation with the physical, chemical and structural properties of polymers. The average size of the local free volume holes in branched poly(ethylene-co-olefin) and poly(propylene-co-olefin) copolymers is studied using Positron Annihilation Lifetime Spectroscopy PALS and correlated with the number and length of the branches and the physical properties determined from Differential Scanning Calorimetry DSC and density measurements. The presence of the n-alkyl branches were found to form sterical hindrances to an effective chain packing resulting in a linear increase in the average free volume hole sizes, an increase in the specific volume of the amorphous phase, a decrease in the sample crystallinity and a decrease in the glass transition and melting temperatures. A linear relation was found between the average size of the free volume holes and the glass transition tem...

  7. The effect of polymeric excipients on the physical properties and performance of amorphous dispersions: Part I, free volume and glass transition.

    Science.gov (United States)

    Li, Jinjiang; Zhao, Junshu; Tao, Li; Wang, Jennifer; Waknis, Vrushali; Pan, Duohai; Hubert, Mario; Raghavan, Krishnaswamy; Patel, Jatin

    2015-02-01

    To investigate the structural effect of polymeric excipients on the behavior of free volume of drug-polymer dispersions in relation to glass transition. Two drugs (indomethacin and ketoconazole) were selected to prepare amorphous dispersions with PVP, PVPVA, HPC, and HPMCAS through spray drying. The physical attributes of the dispersions were characterized using SEM and PXRD. The free volume (hole-size) of the dispersions along with drugs and polymers was measured using positron annihilation lifetime spectroscopy (PALS). Their glass transition temperatures (Tgs) were determined using DSC and DMA. FTIR spectra were recorded to identify hydrogen bonding in the dispersions. The chain structural difference-flexible (PVP and PVPVA) vs. inflexible (HPC and HPMCAS)-significantly impacts the free volume and Tgs of the dispersions as well as their deviation from ideality. Relative to Tg, free volume seems to be a better measure of hydrogen bonding interaction for the dispersions of PVP, HPC, and HPMCAS. The free volume of polymers and their dispersions in general appears to be related to their conformations in solution. Both the backbone chain rigidity of polymers as well as drug-polymer interaction can impact the free volume and glass transition behaviors of the dispersions.

  8. Free volume from positron lifetime and pressure-volume-temperature experiments in relation to structural relaxation of van der Waals molecular glass-forming liquids.

    Science.gov (United States)

    Dlubek, G; Shaikh, M Q; Rätzke, K; Paluch, M; Faupel, F

    2010-06-16

    Positron annihilation lifetime spectroscopy (PALS) is employed to characterize the temperature dependence of the free volume in two van der Waals liquids: 1, 1'-bis(p-methoxyphenyl)cyclohexane (BMPC) and 1, 1'-di(4-methoxy-5-methylphenyl)cyclohexane (BMMPC). From the PALS spectra analysed with the routine LifeTime9.0, the size (volume) distribution of local free volumes (subnanometer size holes), its mean, [v(h)], and mean dispersion, σ(h), were calculated. A comparison with the macroscopic volume from pressure-volume-temperature (PV T) experiments delivered the hole density and the specific hole free volume and a complete characterization of the free volume microstructure in that sense. These data are used in correlation with structural (α) relaxation data from broad-band dielectric spectroscopy (BDS) in terms of the Cohen-Grest and Cohen-Turnbull free volume models. An extension of the latter model allows us to quantify deviations between experiments and theory and an attempt to systematize these in terms of T(g) or of the fragility. The experimental data for several fragile and less fragile glass formers are involved in the final discussion. It was concluded that, for large differences in the fragility of different glass formers, the positron lifetime mirrors clearly the different character of these materials. For small differences in the fragility, additional properties like the character of bonds and chemical structure of the material may affect size, distribution and thermal behaviour of the free volume.

  9. Macrochain configuration, stucture of free volume and transport properties of poly(1-trimethylsilyl-1-propyne) and poly(1-trimethylgermyl-1-propyne)

    KAUST Repository

    Matson, Samira M.

    2012-08-01

    The relationship between poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(1-trimethylger- myl-1-propyne) (PTMGP) microstructure, gas permeability and structure of free volume is reported. n-Butane/methane mixed-gas permeation properties of PTMSP and PTMGP membranes with different cis-/trans-composition have been investigated. The n-butane/methane selectivities for mixed gas are by an order higher than the selectivities calculated from pure gas measurements (the mixed-gas n-butane/methane selectivities are 20-40 for PTMSP and 22-35 for PTMGP). Gas permeability and n-butane/methane selec- tivity essentially differ in polymers with different cis-/trans-composition. Positron annihilation lifetime spec- troscopy investigation of PTMSP and PTMGP with different microstructure has determined distinctions in total amount and structure of free volume, i.e. distribution of free volume elements. The correlation between total amount of free volume and gas transport parameters is established: PTMSP and PTMGP with bigger free volume exhibit higher n-butane permeability and mixed-gas n-butane/methane selectivity. Such behav- ior is discussed in relation to the submolecular structure of polymers with different microstructure and sorp- tion of n-butane in polymers with different free volume. © Pleiades Publishing, Ltd., 2012.

  10. Conductivity equations of protons transporting through 2D crystals obtained with the rate process theory and free volume concept

    Science.gov (United States)

    Hao, Tian; Xu, Yuanze; Hao, Ting

    2018-04-01

    The Eyring's rate process theory and free volume concept are employed to treat protons (or other particles) transporting through a 2D (two dimensional) crystal like graphene and hexagonal boron nitride. The protons are assumed to be activated first in order to participate conduction and the conduction rate is dependent on how much free volume available in the system. The obtained proton conductivity equations show that only the number of conduction protons, proton size and packing structure, and the energy barrier associated with 2D crystals are critical; the quantization conductance is unexpectedly predicted with a simple Arrhenius type temperature dependence. The predictions agree well with experimental observations and clear out many puzzles like much smaller energy barrier determined from experiments than from the density function calculations and isotope separation rate independent of the energy barrier of 2D crystals, etc. Our work may deepen our understandings on how protons transport through a membrane and has direct implications on hydrogen related technology and proton involved bioprocesses.

  11. Study of free volumes of polymer hydrogel and -silicone-hydrogel contact lenses by means of the positron annihilation lifetime spectroscopy method.

    Science.gov (United States)

    Filipecki, Jacek; Kocela, Agnieszka; Korzekwa, Witold

    2014-01-01

    Polymer materials based on hydrogel and silicone-hydrogel materials are commonly used in ophthalmology. It is important to research the structure of these materials, mainly the prevalence of free volumes. The study has been conducted in order to determine the presence of free volume gaps in the structure of polymer hydrogel and silicone-hydrogel contact lenses. In addition, to demonstrate differences in the occurrence of free volumes between types of represented contact lenses. Three different hydrogel and three different silicone-hydrogel polymer contact lenses were used as research material. The study was done by means of positron annihilation lifetime spectroscopy (PALS). As a result of the performed measurements, a graphical curve resulted which describes the relationship between the number of the annihilation acts in the time function. The study revealed the existence of three τ1, τ2 and τ3 components. Significant changes were observed in the ortho-positronium long life component τ3 and their intensities between the examined polymer contact lenses. The conducted study using the Tao-Eldrup model indicates the presence of free volume holes in all research materials. The results lead to the following connection: contact lenses of higher oxygen permeability coefficient (silicone-hydrogel contact lenses) have more and larger free volumes than contact lenses of less oxygen permeability coefficient (hydrogel contact lenses).

  12. Unveiling the relationships among the viscosity equations of glass liquids and colloidal suspensions for obtaining universal equations with the generic free volume concept.

    Science.gov (United States)

    Hao, Tian

    2015-09-14

    The underlying relationships among viscosity equations of glass liquids and colloidal suspensions are explored with the aid of free volume concept. Viscosity equations of glass liquids available in literature are focused and found to have a same physical basis but different mathematical expressions for the free volume. The glass transitions induced by temperatures in glass liquids and the percolation transition induced by particle volume fractions in colloidal suspensions essentially are a second order phase transition: both those two transitions could induce the free volume changes, which in turn determines how the viscosities are going to change with temperatures and/or particle volume fractions. Unified correlations of the free volume to both temperatures and particle volume fractions are thus proposed. The resulted viscosity equations are reducible to many popular viscosity equations currently widely used in literature; those equations should be able to cover many different types of materials over a wide temperature range. For demonstration purpose, one of the simplified versions of those newly developed equations is compared with popular viscosity equations and the experimental data: it can well fit the experimental data over a wide temperature range. The current work reveals common physical grounds among various viscosity equations, deepening our understanding on viscosity and unifying the free volume theory across many different systems.

  13. A New Pentiptycene-Based Dianhydride and Its High-Free-Volume Polymer for Carbon Dioxide Removal.

    Science.gov (United States)

    Shamsabadi, Ahmad Arabi; Seidi, Farzad; Nozari, Mohammad; Soroush, Masoud

    2018-01-23

    In addition to possessing excellent chemical, mechanical, and thermal stability, polyimides and polyetherimides have excellent solubility in many solvents, which renders them suitable for membrane preparation. Two new monomers [a pentiptycene-based dianhydride (PPDAn) and a pentiptycene imide-containing diamine (PPImDA)] and a pentiptycene-based polyimide [PPImDA-4,4'-hexafluoroisopropylidene diphthalic anhydride (PPImDA-6FDA)] have been synthesized and characterized by FTIR and 1 H NMR spectroscopy, gel-permeation chromatography, mass spectrometry, X-ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry, BET surface area, and X-ray diffraction. High-molecular-weight PPImDA-6FDA has remarkable thermal stability and excellent solubility in common organic solvents. It also has an extraordinarily high fractional free volume (0.233) owing to the presence of -C(CF 3 ) 2 - units, the rigid diamine, and the pentiptycene moiety in the polymer structure. It has high CO 2 permeability (812 Barrer) owing to poor chain packing, which is caused by the fact that its rigid groups veil the influence of the ethereal oxygen groups in its backbone. It has the highest CO 2 permeability among all reported pentiptycene-containing polymers (about six times higher than that of the most permeable one) without sacrificing selectivity. The high free volume, good microporosity, high solubility in many solvents, and remarkable thermal stability of PPImDA-6FDA point to the great potential of this polymer for CO 2 removal. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Birth Defects

    Science.gov (United States)

    A birth defect is a problem that happens while a baby is developing in the mother's body. Most birth defects happen during the first 3 months of ... in the United States is born with a birth defect. A birth defect may affect how the ...

  15. Thermal properties of defective fullerene

    Science.gov (United States)

    Li, Jian; Zheng, Dong-Qin; Zhong, Wei-Rong

    2016-09-01

    We have investigated the thermal conductivity of defective fullerene (C60) by using the nonequilibrium molecular dynamics (MD) method. It is found that the thermal conductivity of C60 with one defect is lower than the thermal conductivity of perfect C60. However, double defects in C60 have either positive or negative influence on the thermal conductivity, which depends on the positions of the defects. The phonon spectra of perfect and defective C60 are also provided to give corresponding supports. Our results can be extended to long C60 chains, which is helpful for the thermal management of C60.

  16. Duty factor variation possibility from 1% to 100% with PKU microwave driven Cs-free volume H- sources

    Science.gov (United States)

    Peng, S. X.; Zhang, T.; Ren, H. T.; Zhang, A. L.; Xu, Y.; Zhang, J. F.; Guo, Z. Y.; Chen, J. E.

    2016-02-01

    Microwave driven cesium-free volume H- sources, that have the ability to deliver tens of mA H- at 35 keV both in CW and 10% duty factor (100 Hz/1 ms), were developed at Peking University (PKU) [S. X. Peng et al., in Proceeding of IPAC 2015, WEPWA027, Richmond, Virginia, USA, 3-8 May 2015]. Recently, special efforts were paid on the investigation of duty factor variation possibility from 1% to 100% with them. Most of the experiments were carried out with a pulsed length (τ) of 1 ms and different intervals of 99 ms, 49 ms, 39 ms, 29 ms, 19 ms, 9 ms, 4 ms, 2 ms, 1 ms, 0.5 ms, and 0 ms, respectively. Other experiments were focused on CW operation and fixed duty factor of 1%. Experimental results prove that PKU H- sources can deliver tens of mA H- at duty factor from 1% to 100%. The RF power efficiency increases steadily with the increasing of duty factor from 1% to CW at a fixed pulsed length. Under a given duty factor and pulsed length, RF power efficiency keeps constant and the H- current increases with RF power linearly. Details will be presented in the paper.

  17. Duty factor variation possibility from 1% to 100% with PKU microwave driven Cs-free volume H⁻ sources.

    Science.gov (United States)

    Peng, S X; Zhang, T; Ren, H T; Zhang, A L; Xu, Y; Zhang, J F; Guo, Z Y; Chen, J E

    2016-02-01

    Microwave driven cesium-free volume H(-) sources, that have the ability to deliver tens of mA H(-) at 35 keV both in CW and 10% duty factor (100 Hz/1 ms), were developed at Peking University (PKU) [S. X. Peng et al., in Proceeding of IPAC 2015, WEPWA027, Richmond, Virginia, USA, 3-8 May 2015]. Recently, special efforts were paid on the investigation of duty factor variation possibility from 1% to 100% with them. Most of the experiments were carried out with a pulsed length (τ) of 1 ms and different intervals of 99 ms, 49 ms, 39 ms, 29 ms, 19 ms, 9 ms, 4 ms, 2 ms, 1 ms, 0.5 ms, and 0 ms, respectively. Other experiments were focused on CW operation and fixed duty factor of 1%. Experimental results prove that PKU H(-) sources can deliver tens of mA H(-) at duty factor from 1% to 100%. The RF power efficiency increases steadily with the increasing of duty factor from 1% to CW at a fixed pulsed length. Under a given duty factor and pulsed length, RF power efficiency keeps constant and the H(-) current increases with RF power linearly. Details will be presented in the paper.

  18. A fractional transient model for the viscoplastic response of polymers based on a micro-mechanism of free volume distribution

    Science.gov (United States)

    Spathis, G.; Kontou, E.

    2017-11-01

    In the present work, the nonlinear viscoelastic/viscoplastic response of polymeric materials is described by introducing essential modifications on a model developed in previous works. A constitutive equation of viscoelasticity, based on the transient network theory, is introduced in a more generalized form, which takes into account volume changes during deformation. This time-dependent equation accounts for the nonlinearity and viscoplasticity at small elastic and finite plastic strain regime. The present description was proved to be more flexible, given that it contains a relaxation function that has been derived by considering instead of first order kinetics a fractional derivative that controls the rate of molecular chain detachment from their junctions. Therefore, the new equation has a more global character, appropriate for cases where heavy tails are expected. On the basis of the distributed nature of free volume, a new functional form of the rate of plastic deformation is developed, which is combined with a proper kinematic formulation and leads to the separation of the total strain into the elastic and plastic part. A three-dimensional constitutive equation is then derived for an isotropic, compressible medium. This analysis was proved to be capable of capturing the main aspects of inelastic response as well as the instability stage taking place at the tertiary creep, related to the creep failure.

  19. Free volume of an epoxy resin and its relation to structural relaxation: evidence from positron lifetime and pressure-volume-temperature experiments.

    Science.gov (United States)

    Dlubek, Günter; Hassan, E M; Krause-Rehberg, Reinhard; Pionteck, Jürgen

    2006-03-01

    The microstructure of the free volume and its temperature dependence in the epoxy resin diglycidyl ether of bisphenol-A (DGEBA) have been examined using positron annihilation lifetime spectroscopy (PALS, 80-350K, 10(-5) Pa) and pressure-volume-temperature (PVT, 293-470 K, 0.1-200MPa) experiments. Employing the Simha-Somcynsky lattice-hole theory (S-S eos), the excess (hole) free volume fraction h and the specific free and occupied volumes, Vf=hV and Vocc=(1-h)V, were estimated. From the PALS spectra analyzed with the new routine LT9.0 the hole size distribution, its mean, , and mean dispersion, sigma h, were calculated. varies from 35 130 A3. From a comparison of with V and Vf, the specific hole number N'h was estimated to be independent of the temperature [Nh(300 K)=N'h/V=0.65 nm-3]. From comparison with reported dielectric and viscosity measurements, we found that the structural relaxation slows down faster than the shrinkage of the hole free volume Vf would predict on the basis of the free volume theory. Our results indicate that the structural relaxation in DGEBA operates via the free-volume mechanism only when liquidlike clusters of cells of the S-S lattice appear which contain a local free volume of approximately 1.5 or more empty S-S cells. The same conclusion follows from the pressure dependency of the structural relaxation and Vf. It is shown that PALS mirrors thermal volume fluctuations on a subnanometer scale via the dispersion in the ortho-positronium lifetimes. Using a fluctuation approach, the temperature dependency of the characteristic length of dynamic heterogeneity, xi, is estimated to vary from xi=1.9 nm at Tg to 1.0 nm at T/Tg>1.2. A model was proposed which relates the spatial structure of the free volume as concluded from PALS to the known mobility pattern of the dynamic glass transition at low (cooperative alpha-relaxation) and high (alpha-relaxation) temperatures. We discuss possible reasons for the differences between the results of our

  20. High-precision absolute (true) density measurements on hygroscopic powders by gas pycnometry: application to determining effects of formulation and process on free volume of lyophilized products.

    Science.gov (United States)

    Kikuchi, Takayuki; Wang, Bingquan Stuart; Pikal, Michael J

    2011-07-01

    As density (free volume) of the amorphous solids should be related to mobility and stability, an attempt was made to develop a simple, sensitive, and reproducible method to evaluate free volume via high-precision gas pycnometry density measurements, and to apply this methodology to study the variation of free volume with formulation and thermal history (i.e., annealing). Annealed samples were prepared either by heating the product after freeze drying (postannealing) or drying at higher temperature in secondary drying than normal (in-process annealing). Density was measured using a gas pycnometer. We find that the key to high-precision density measurements is isolation of the instrument from atmospheric moisture; accordingly, all operations were carried out in a dry box. With suitable care, densities of amorphous freeze-dried products can be measured with a precision of better than 0.5% in a series of independent but nominally identical samples. Density decreased with increasing molecular weight of dextran, but density of proteins was independent of molecular weight. Small but significant increases in density upon annealing were observed for several formulations. Thus, we conclude that accurate density measurements may be made by carefully controlling residual moisture. Density may be a useful parameter to predict long-term stability. Copyright © 2011 Wiley-Liss, Inc. and the American Pharmacists Association

  1. Positron annihilation lifetime studies of changes in free volume on some biorelevant nitrogen heterocyclic compounds and their S-glycosylation

    International Nuclear Information System (INIS)

    Mahmoud, K.R.; Khodair, A.I.; Shaban, S.Y.

    2015-01-01

    A series of N-heterocyclic compounds was investigated by positron annihilation lifetime spectroscopy as well as Doppler broadening of annihilation radiation (DBAR) at room temperature. The results showed that the formation probability and life time of ortho-positronium in this series are structure and electron-donation character dependent, and can give more information about the structure. The DBAR provides direct information about the change of core and valance electrons as well as the number of defect types present in these compounds. - Highlights: • N-heterocyclic compounds were studied by PALS and DBAR at room temperature. • These compounds contain thiohydantoins which have wide applications as anticarcinogenic, antiviral, human immunodeficiency virus (HIV) and antimicrobial activity. • The DBAR provides direct information about the change of core and valance electrons as well as the number of defect types present in these compounds.

  2. Defects and defect processes in nonmetallic solids

    CERN Document Server

    Hayes, W

    2004-01-01

    This extensive survey covers defects in nonmetals, emphasizing point defects and point-defect processes. It encompasses electronic, vibrational, and optical properties of defective solids, plus dislocations and grain boundaries. 1985 edition.

  3. Positron annihilation lifetime studies of changes in free volume on some biorelevant nitrogen heterocyclic compounds and their S-glycosylation.

    Science.gov (United States)

    Mahmoud, K R; Khodair, A I; Shaban, S Y

    2015-11-01

    A series of N-heterocyclic compounds was investigated by positron annihilation lifetime spectroscopy as well as Doppler broadening of annihilation radiation (DBAR) at room temperature. The results showed that the formation probability and life time of ortho-positronium in this series are structure and electron-donation character dependent, and can give more information about the structure. The DBAR provides direct information about the change of core and valance electrons as well as the number of defect types present in these compounds. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Extended Emotions

    DEFF Research Database (Denmark)

    Krueger, Joel; Szanto, Thomas

    2016-01-01

    Until recently, philosophers and psychologists conceived of emotions as brain- and body-bound affairs. But researchers have started to challenge this internalist and individualist orthodoxy. A rapidly growing body of work suggests that some emotions incorporate external resources and thus extend...... beyond the neurophysiological confines of organisms; some even argue that emotions can be socially extended and shared by multiple agents. Call this the extended emotions thesis (ExE). In this article, we consider different ways of understanding ExE in philosophy, psychology, and the cognitive sciences....... First, we outline the background of the debate and discuss different argumentative strategies for ExE. In particular, we distinguish ExE from cognate but more moderate claims about the embodied and situated nature of cognition and emotion (Section 1). We then dwell upon two dimensions of ExE: emotions...

  5. Extended thermodynamics

    CERN Document Server

    Müller, Ingo

    1993-01-01

    Physicists firmly believe that the differential equations of nature should be hyperbolic so as to exclude action at a distance; yet the equations of irreversible thermodynamics - those of Navier-Stokes and Fourier - are parabolic. This incompatibility between the expectation of physicists and the classical laws of thermodynamics has prompted the formulation of extended thermodynamics. After describing the motifs and early evolution of this new branch of irreversible thermodynamics, the authors apply the theory to mon-atomic gases, mixtures of gases, relativistic gases, and "gases" of phonons and photons. The discussion brings into perspective the various phenomena called second sound, such as heat propagation, propagation of shear stress and concentration, and the second sound in liquid helium. The formal mathematical structure of extended thermodynamics is exposed and the theory is shown to be fully compatible with the kinetic theory of gases. The study closes with the testing of extended thermodynamics thro...

  6. Extended ERP

    OpenAIRE

    Müssigmann, Nikolaus

    2005-01-01

    Extended ERP : dynamic strategic supply network development / A. Albani, N. Müssigmann, K. Turowski. - In: ICESAcc 2005 - Second International Conference on Enterprise Systems and Accounting / C. J. Stefanou. - Thessaloniki : Labor. of Enterprise Resources Dep. of Accounting, 2005. - 1 CD-ROM

  7. Embedded defects

    International Nuclear Information System (INIS)

    Barriola, M.; Vachaspati, T.; Bucher, M.

    1994-01-01

    We give a prescription for embedding classical solutions and, in particular, topological defects in field theories which are invariant under symmetry groups that are not necessarily simple. After providing examples of embedded defects in field theories based on simple groups, we consider the electroweak model and show that it contains the Z string and a one-parameter family of strings called the W(α) string. It is argued that although the members of this family are gauge equivalent when considered in isolation, each member becomes physically distinct when multistring configurations are considered. We then turn to the issue of stability of embedded defects and demonstrate the instability of a large class of such solutions in the absence of bound states or condensates. The Z string is shown to be unstable for all values of the Higgs boson mass when θ W =π/4. W strings are also shown to be unstable for a large range of parameters. Embedded monopoles suffer from the Brandt-Neri-Coleman instability. Finally, we connect the electroweak string solutions to the sphaleron

  8. Extending Puppet

    CERN Document Server

    Franceschi, Alessandro

    2014-01-01

    This book is a clear, detailed and practical guide to learn about designing and deploying you puppet architecture, with informative examples to highlight and explain concepts in a focused manner. This book is designed for users who already have good experience with Puppet, and will surprise experienced users with innovative topics that explore how to design, implement, adapt, and deploy a Puppet architecture. The key to extending Puppet is the development of types and providers, for which you must be familiar with Ruby.

  9. 2010 Defects in Semiconductors GRC

    Energy Technology Data Exchange (ETDEWEB)

    Shengbai Zhang

    2011-01-06

    Continuing its tradition of excellence, this Gordon Conference will focus on research at the forefront of the field of defects in semiconductors. The conference will have a strong emphasis on the control of defects during growth and processing, as well as an emphasis on the development of novel defect detection methods and first-principles defect theories. Electronic, magnetic, and optical properties of bulk, thin film, and nanoscale semiconductors will be discussed in detail. In contrast to many conferences, which tend to focus on specific semiconductors, this conference will deal with point and extended defects in a broad range of electronic materials. This approach has proved to be extremely fruitful for advancing fundamental understanding in emerging materials such as wide-band-gap semiconductors, oxides, sp{sup 2} carbon based-materials, and photovoltaic/solar cell materials, and in understanding important defect phenomena such as doping bottleneck in nanostructures and the diffusion of defects and impurities. The program consists of about twenty invited talks and a number of contributed poster sessions. The emphasis should be on work which has yet to be published. The large amount of discussion time provides an ideal forum for dealing with topics that are new and/or controversial.

  10. A modified free-volume-based model for predicting vapor-liquid and solid-liquid equilibria for size asymmetric systems

    DEFF Research Database (Denmark)

    Radfarnia, H.R.; Ghotbi, C.; Taghikhani, V.

    2005-01-01

    The main purpose of this work is to present a free-volume combinatorial term in predicting vapor-liquid equilibrium (VLE) and solid-liquid equilibrium (SLE) of polymer/solvent and light and heavy hydrocarbon/hydrocarbon mixtures. The proposed term is based on a modification of the original Freed...... by Karman et al. The results obtained from the proposed model showed that better improvement can be attained for the polymer systems with energetic interactions as well as for VLE and SLE study of heavy alkane solutes in light alkane solvents. This observation can be further verified by comparison...... of the results obtained from the proposed model with those of the molecular simulation data. (c) 2005 Elsevier B.V. All rights reserved....

  11. On the relation between free volume and powder pressure with the gas stream in the powder moving-bed; Gasu nagare wo tomonau kotai idoso ni okeru kukanritsu to ryutaiatsu no kankei ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Tomoyasu, Suminao; Yoshino, Akio; Iwata, Hiroshi; Kawazoe, Hiromitsu

    1999-04-05

    On the stand pipe with gas stream equipped the bottom in fluidized bed from powder and equation of continuity of the gas, equation of momentum balance considering frictional force of wall surface and equation of pressure loss of the gas by relative speed and test data on the axial gas pressure distribution besides with stand pipe axial direction powder pressure {sigma}{sub z} relational expression of free volume {epsilon} it asks ask. According to this result, (1) d{sigma}{sub z}/d{epsilon} is increased in free volume or big part in the stand pipe entrance, and it once lowers in the middle, and in addition, it increases in the downward again. That is to say, the inflection point of the powder pressure does the right and presence in the. intermediate. (2) There is mainly the high possibility by the effect of the frictional force of stand pipe wall surface on d{sigma}{sub z}/d{epsilon} increasing in the stand pipe inlet vicinity. (3) The powder pressure is not only free volume but also function of the powder particle diameter too. And, this powder ratio and free volume also showed that the distribution of amount of gas which flow and axial gas pressure, powder pressure, free volume, etc. was obtained the stand pipe from relational expression of particle size and other theoretical formula. (translated by NEDO)

  12. Determination of defect content and defect profile in semiconductor heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zubiaga, A [Laboratory of Physics, HUT, PO Box 1100, 02015 TKK, Espoo (Finland); Garcia, J A; Plazaola, F [Zientzia eta Teknologia Fakultatea, Euskal Herriko Unbertsitatea, P. K. 644, 48080, Bilbao (Spain); Zuniga-Perez, J; Munoz-Sanjose, V, E-mail: fernando.plazaola@ehu.es [Universitat de Valencia, Departamento de Fisica Aplicada i Electromagnetisme, Dr. Moliner 50, 46100 Burjassot, Valencia (Spain)

    2011-01-10

    In this article we present an overview of the technique to obtain the defects depth profile and width of a deposited layer and multilayer based on positron annihilation spectroscopy. In particular we apply the method to ZnO and ZnO/ZnCdO layers deposited on sapphire substrates. After introducing some terminology we first calculate the trend that the W/S parameters of the Doppler broadening measurements must follow, both in a qualitative and quantitative way. From this point we extend the results to calculate the width and defect profiles in deposited layer samples.

  13. Coagulation defects.

    Science.gov (United States)

    Soliman, Doreen E; Broadman, Lynn M

    2006-09-01

    The present understanding of the coagulation process emphasizes the final common pathway and the proteolytic systems that result in the degradation of formed clots and the prevention of unwanted clot formations, as well as a variety of defense systems that include tissue repair, autoimmune processes, arteriosclerosis, tumor growth, the spread of metastases, and defense systems against micro-organisms. This article discusses diagnosis and management of some of the most common bleeding disorders. The goals are to provide a simple guide on how best to manage patients afflicted with congenital or acquired clotting abnormalities during the perioperative period, present a brief overview of the methods of testing and monitoring the coagulation defects, and discuss the appropriate pharmacologic or blood component therapies for each disease.

  14. Consciousness extended

    DEFF Research Database (Denmark)

    Carrara-Augustenborg, Claudia

    2012-01-01

    There is no consensus yet regarding a conceptualization of consciousness able to accommodate all the features of such complex phenomenon. Different theoretical and empirical models lend strength to both the occurrence of a non-accessible informational broadcast, and to the mobilization of specific...... brain areas responsible for the emergence of the individual´s explicit and variable access to given segments of such broadcast. Rather than advocating one model over others, this chapter proposes to broaden the conceptualization of consciousness by letting it embrace both mechanisms. Within...... such extended framework, I propose conceptual and functional distinctions between consciousness (global broadcast of information), awareness (individual´s ability to access the content of such broadcast) and unconsciousness (focally isolated neural activations). My hypothesis is that a demarcation in terms...

  15. Extending Experiences

    DEFF Research Database (Denmark)

    A computer game's player is experiencing not only the game as a designer-made artefact, but also a multitude of social and cultural practices and contexts of both computer game play and everyday life. As a truly multidisciplinary anthology, Extending Experiences sheds new light on the mesh...... of possibilities and influences the player engages with. Part one, Experiential Structures of Play, considers some of the key concepts commonly used to address the experience of a computer game player. The second part, Bordering Play, discusses conceptual and practical overlaps of games and everyday life...... and the impacts of setting up, crossing and breaking the boundaries of game and non-game. Part three, Interfaces of Play, looks at games as technological and historical artefacts and commodities. The fourth part, Beyond Design, introduces new models for the practical and theoretical dimensions of game design....

  16. Substitution and defect chemistry of La-Cu-O systems

    International Nuclear Information System (INIS)

    Gai, P.L.; McCarron, E.M.; Kunchur, M.

    1991-01-01

    In this paper substitutional effects of strontium in La-Cu-O system and defects accommodating stoichiometric deviations is investigated. The extended shear defects are analyzed using electron microscopy and the role in superconducting transport properties has been examined by magnetic measurements. The initial results suggest that the defects enhance flux pinning

  17. Modeling and experimental characterization of stepped and v-shaped (311) defects in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Marqués, Luis A., E-mail: lmarques@ele.uva.es; Aboy, María [Departamento de Electrónica, Universidad de Valladolid, E.T.S.I. de Telecomunicación, 47011 Valladolid (Spain); Dudeck, Karleen J.; Botton, Gianluigi A. [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L7 (Canada); Knights, Andrew P. [Department of Engineering Physics, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L7 (Canada); Gwilliam, Russell M. [Surrey Ion Beam Centre, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

    2014-04-14

    We propose an atomistic model to describe extended (311) defects in silicon. It is based on the combination of interstitial and bond defect chains. The model is able to accurately reproduce not only planar (311) defects but also defect structures that show steps, bends, or both. We use molecular dynamics techniques to show that these interstitial and bond defect chains spontaneously transform into extended (311) defects. Simulations are validated by comparing with precise experimental measurements on actual (311) defects. The excellent agreement between the simulated and experimentally derived structures, regarding individual atomic positions and shape of the distinct structural (311) defect units, provides strong evidence for the robustness of the proposed model.

  18. Neural Tube Defects

    Science.gov (United States)

    Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the ... that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In ...

  19. Duty factor variation possibility from 1% to 100% with PKU microwave driven Cs-free volume H{sup −} sources

    Energy Technology Data Exchange (ETDEWEB)

    Peng, S. X., E-mail: sxpeng@pku.edu.cn; Zhang, T.; Ren, H. T.; Xu, Y.; Zhang, J. F.; Guo, Z. Y. [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); Zhang, A. L. [University of Chinese Academy of Sciences, Beijing 100049 (China); Chen, J. E. [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2016-02-15

    Microwave driven cesium-free volume H{sup −} sources, that have the ability to deliver tens of mA H{sup −} at 35 keV both in CW and 10% duty factor (100 Hz/1 ms), were developed at Peking University (PKU) [S. X. Peng et al., in Proceeding of IPAC 2015, WEPWA027, Richmond, Virginia, USA, 3–8 May 2015]. Recently, special efforts were paid on the investigation of duty factor variation possibility from 1% to 100% with them. Most of the experiments were carried out with a pulsed length (τ) of 1 ms and different intervals of 99 ms, 49 ms, 39 ms, 29 ms, 19 ms, 9 ms, 4 ms, 2 ms, 1 ms, 0.5 ms, and 0 ms, respectively. Other experiments were focused on CW operation and fixed duty factor of 1%. Experimental results prove that PKU H{sup −} sources can deliver tens of mA H{sup −} at duty factor from 1% to 100%. The RF power efficiency increases steadily with the increasing of duty factor from 1% to CW at a fixed pulsed length. Under a given duty factor and pulsed length, RF power efficiency keeps constant and the H{sup −} current increases with RF power linearly. Details will be presented in the paper.

  20. Effect of Rare-Earth Doping on Free-Volume Nanostructure of Ga-Codoped Glassy (As/Sb)2Se3

    Science.gov (United States)

    Shpotyuk, Yaroslav

    2017-03-01

    Subsequent stages of atomic-deficient nanostructurization finalizing rare-earth functionality under Pr3+-doping in Ga2(As0.28Sb0.12Se0.60)98 glass are studied employing method of positron annihilation lifetime spectroscopy. Genesis of free-volume positron trapping sites, composed of atomic-accessible geometrical holes (void cores) arrested by surrounding atomic-inaccessible Se-based bond-free solid angles (void shells), are disclosed for parent As2Se3, Ga-codoped Ga2(As0.40Se0.60)98, as well as Ga-codoped and Sb-modified Ga2(As0.28Sb0.12Se0.60)98 glasses. The finalizing nanostructurization due to Pr3+-doping (500 wppm) in glassy Ga2(As0.28Sb0.12Se0.60)98 is explained in terms of competitive contribution of changed occupancy sites available for both rare-earth ions and positrons.

  1. Insights into Free Volume Variations across Ion-Exchange Membranes upon Mixed Solvents Uptake by Small and Ultrasmall Angle Neutron Scattering.

    Science.gov (United States)

    Allioux, Francois-Marie; Garvey, Christopher J; Rehm, Christine; Tardy, Blaise L; Dagastine, Raymond Riley; Hodgson, Peter D; Kong, Lingxue; Dumée, Ludovic Francis

    2017-03-15

    Ion-exchange membranes are composite separation materials increasingly used in a variety of electro-membranes and electrochemical processes. Although promising for solvent reclamation, to date, their main applications are limited to aqueous environments due to physicochemical and microstructural changes of the materials upon exposure to nonaqueous and mixed solvents solutions, affecting long-term stability and separation performance. In the present work, the structural changes of commercial and novel hybrid ion-exchange membranes in mixed methanol/water and ethanol/water solutions are assessed for the first time using ultra- and small-angle neutron scattering techniques. The interface between the ion-exchange functional layer and the mechanical support of the membranes is evaluated in the ultralow-q region, while a broad solvent-dependent peak at the mid-q region was correlated to the microstructural properties which are related to the free volume across the ion-exchange domains and to the materials electrical and nanoscale mechanical properties. The results of this study may offer new opportunities toward the development of an efficient separation process using ion-exchange membranes for the purification of fermentation broths toward biofuel generation.

  2. Effects of excipients on the tensile strength, surface properties and free volume of Klucel® free films of pharmaceutical importance

    Science.gov (United States)

    Gottnek, Mihály; Süvegh, Károly; Pintye-Hódi, Klára; Regdon, Géza

    2013-08-01

    The physicochemical properties of polymers planned to be applied as mucoadhesive films were studied. Two types of Klucel® hydroxypropylcellulose (LF and MF) were used as film-forming polymers. Hydroxypropylcellulose was incorporated in 2 w/w% with glycerol and xylitol as excipients and lidocaine base as an active ingredient at 5, 10 or 15 w/w% of the mass of the film-forming polymer. The free volume changes of the films were investigated by positron annihilation lifetime spectroscopy, the mechanical properties of the samples were measured with a tensile strength tester and contact angles were determined to assess the surface properties of the films. It was found that the Klucel® MF films had better physicochemical properties than those of the LF films. Klucel® MF as a film-forming polymer with lidocaine base and both excipients at 5 w/w% exhibited physicochemical properties and good workability. The excipients proved to exert strong effects on the physicochemical properties of the tested systems and it is very important to study them intensively in preformulation studies in the pharmaceutical technology in order to utilise their benefits and to avoid any disadvantageous effects.

  3. Formation of defect-free 6FDA-DAM asymmetric hollow fiber membranes for gas separations

    KAUST Repository

    Xu, Liren

    2014-06-01

    This paper reports the formation of defect-free 6FDA-DAM asymmetric hollow fiber membranes. 6FDA-polyimides are of great interest for advanced gas separation membranes, and 6FDA-DAM polyimide is a representative polymer in this family with attractive dense film properties for several potential applications. The work reported here for the 6FDA-DAM polyimide provides insight for the challenging fabrication of defect-free asymmetric hollow fiber membranes for this class of 6FDA-polyimides, which behave rather different from lower free volume polymers. Specifically, the 6FDA based materials show relatively slow phase separation rate in water quench baths, which presents a challenge for fiber spinning. For convenience, we refer to the behavior as more "non-solvent resistant" in comparison to other lower free volume polymers, since the binodal phase boundary is displaced further from the conventional position near the pure polymer-solvent axis on a ternary phase diagram in conventional polymers like Matrimid® and Ultem®. The addition of lithium nitrate to promote phase separation has a useful impact on 6FDA-DAM asymmetric hollow fiber formation. 6FDA-DAM phase diagrams using ethanol and water as non-solvent are reported, and it was found that water is less desirable as a non-solvent dope additive for defect-free fiber spinning. Phase diagrams are also reported for 6FDA-DAM dope formulation with and without the addition of lithium nitrate, and defect-free asymmetric hollow fiber membranes are reported for both cases. The effect of polymer molecular weight on defect-free fiber spinning was also investigated. Gas transport properties and morphology of hollow fibers were characterized. With several thorough case studies, this work provides a systematic guideline for defect-free fiber formation from 6FDA-polymers. © 2014 Elsevier B.V.

  4. Correlation of Gas Permeability in a Metal-Organic Framework MIL-101(Cr)-Polysulfone Mixed-Matrix Membrane with Free Volume Measurements by Positron Annihilation Lifetime Spectroscopy (PALS).

    Science.gov (United States)

    Jeazet, Harold B Tanh; Koschine, Tönjes; Staudt, Claudia; Raetzke, Klaus; Janiak, Christoph

    2013-10-25

    Hydrothermally stable particles of the metal-organic framework MIL-101(Cr) were incorporated into a polysulfone (PSF) matrix to produce mixed-matrix or composite membranes with excellent dispersion of MIL-101 particles and good adhesion within the polymer matrix. Pure gas (O2, N2, CO2 and CH4) permeation tests showed a significant increase of gas permeabilities of the mixed-matrix membranes without any loss in selectivity. Positron annihilation lifetime spectroscopy (PALS) indicated that the increased gas permeability is due to the free volume in the PSF polymer and the added large free volume inside the MIL-101 particles. The trend of the gas transport properties of the composite membranes could be reproduced by a Maxwell model.

  5. Correlation of Gas Permeability in a Metal-Organic Framework MIL-101(Cr)–Polysulfone Mixed-Matrix Membrane with Free Volume Measurements by Positron Annihilation Lifetime Spectroscopy (PALS)

    Science.gov (United States)

    Jeazet, Harold B. Tanh; Koschine, Tönjes; Staudt, Claudia; Raetzke, Klaus; Janiak, Christoph

    2013-01-01

    Hydrothermally stable particles of the metal-organic framework MIL-101(Cr) were incorporated into a polysulfone (PSF) matrix to produce mixed-matrix or composite membranes with excellent dispersion of MIL-101 particles and good adhesion within the polymer matrix. Pure gas (O2, N2, CO2 and CH4) permeation tests showed a significant increase of gas permeabilities of the mixed-matrix membranes without any loss in selectivity. Positron annihilation lifetime spectroscopy (PALS) indicated that the increased gas permeability is due to the free volume in the PSF polymer and the added large free volume inside the MIL-101 particles. The trend of the gas transport properties of the composite membranes could be reproduced by a Maxwell model. PMID:24957061

  6. Accurate modeling of defects in graphene transport calculations

    Science.gov (United States)

    Linhart, Lukas; Burgdörfer, Joachim; Libisch, Florian

    2018-01-01

    We present an approach for embedding defect structures modeled by density functional theory into large-scale tight-binding simulations. We extract local tight-binding parameters for the vicinity of the defect site using Wannier functions. In the transition region between the bulk lattice and the defect the tight-binding parameters are continuously adjusted to approach the bulk limit far away from the defect. This embedding approach allows for an accurate high-level treatment of the defect orbitals using as many as ten nearest neighbors while keeping a small number of nearest neighbors in the bulk to render the overall computational cost reasonable. As an example of our approach, we consider an extended graphene lattice decorated with Stone-Wales defects, flower defects, double vacancies, or silicon substitutes. We predict distinct scattering patterns mirroring the defect symmetries and magnitude that should be experimentally accessible.

  7. RKKY interaction between extended magnetic defect lines in graphene

    DEFF Research Database (Denmark)

    Gorman, P. D.; Duffy, J. M.; Power, Stephen

    2014-01-01

    Of fundamental interest in the field of spintronics is the mechanism of indirect exchange coupling between magnetic impurities embedded in metallic hosts. A range of physical features, such as magnetotransport and overall magnetic moment formation, are predicated upon this magnetic coupling, ofte...... consequences for the spintronic application of magnetically-doped systems, and we illustrate this with a simple magnetoresistance device....

  8. Effects of the molecular level dispersion of graphene oxide on the free volume characteristics of poly(vinyl alcohol) and its impact on the thermal and mechanical properties of their nanocomposites.

    Science.gov (United States)

    Sharma, S K; Prakash, J; Pujari, P K

    2015-11-21

    Poly(vinyl alcohol), PVA, reinforced with carbon nanofillers has shown drastic variations in thermal as well as mechanical properties. In order to establish structure-property correlations, these variations have been correlated with modifications in the hydrogen bonding structure as well as the crystallinity of the PVA matrix without paying much attention to molecular packing in the amorphous region of this semicrystalline polymer. In order to investigate the molecular packing in PVA-graphene oxide (GO) nanocomposites, free volume characterization of PVA-GO nanocomposites has been carried out using ortho-positronium (o-Ps) probe. The variations in free volume size, density and size distribution have been determined through o-Ps lifetime and the corresponding intensity as well as its lifetime distribution. The variation in hydrogen bonding and its effect on crystallinity has been determined by Fourier Transform Infra Red (FTIR) and X-ray diffraction (XRD) measurements. The variation in the thermal (glass transition temperature) and mechanical (Young's modulus, tensile strength and percentage strain at break) properties of the nanocomposites is explained in view of the free volume structure and crystallinity of the PVA matrix which are severely modified due to the molecular-level dispersion of GO sheets in the PVA matrix.

  9. Defect of the Eyelids.

    Science.gov (United States)

    Lu, Guanning Nina; Pelton, Ron W; Humphrey, Clinton D; Kriet, John David

    2017-08-01

    Eyelid defects disrupt the complex natural form and function of the eyelids and present a surgical challenge. Detailed knowledge of eyelid anatomy is essential in evaluating a defect and composing a reconstructive plan. Numerous reconstructive techniques have been described, including primary closure, grafting, and a variety of local flaps. This article describes an updated reconstructive ladder for eyelid defects that can be used in various permutations to solve most eyelid defects. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Computer experiment studies on mechanisms for irradiation induced defect production and annealing processes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Beeler, J.R. Jr.; Beeler, M.F.

    1979-06-01

    This research is based on pair potentials used in the Brookhaven work. It extends their use in defect production simulations to the 5 MeV range and characterizes the short term annealing of the primary defect states. Defect properties and interactions are studied. Defect interactions include carbon, helium, and misfit metallic substitutional impurity interactions with vacancy and interstitial defects as well as vacancy-vacancy, interstitial-interstitial and vacancy-interstitial interactions. (FS)

  11. Computer experiment studies on mechanisms for irradiation induced defect production and annealing processes. Final report

    International Nuclear Information System (INIS)

    Beeler, J.R. Jr.; Beeler, M.F.

    1979-06-01

    This research is based on pair potentials used in the Brookhaven work. It extends their use in defect production simulations to the 5 MeV range and characterizes the short term annealing of the primary defect states. Defect properties and interactions are studied. Defect interactions include carbon, helium, and misfit metallic substitutional impurity interactions with vacancy and interstitial defects as well as vacancy-vacancy, interstitial-interstitial and vacancy-interstitial interactions

  12. Classifying defects in pallet stringers by ultrasonic scanning

    Science.gov (United States)

    Mohammed F. Kabir; Daniel L. Schmoldt; Philip A. Araman; Mark E. Schafer; Sang-Mook Lee

    2003-01-01

    Detecting and classifying defects are required to grade and sort pallet parts. Use of quality parts can extend the life cycle of pallets and can reduce long-term cost. An investigation has been carried out to detect and classify defects in yellow-poplar (Liriodendron tulipifera, L.) and red oak (Quercus rubra, L.) stringers using ultrasonic scanning. Data were...

  13. On holographic defect entropy

    Energy Technology Data Exchange (ETDEWEB)

    Estes, John [Blackett Laboratory, Imperial College,London SW7 2AZ (United Kingdom); Jensen, Kristan [Department of Physics and Astronomy, University of Victoria,Victoria, BC V8W 3P6 (Canada); C.N. Yang Institute for Theoretical Physics, SUNY Stony Brook,Stony Brook, NY 11794-3840 (United States); O’Bannon, Andy [Rudolf Peierls Centre for Theoretical Physics, University of Oxford,1 Keble Road, Oxford OX1 3NP (United Kingdom); Tsatis, Efstratios [8 Kotylaiou Street, Athens 11364 (Greece); Wrase, Timm [Stanford Institute for Theoretical Physics, Stanford University,Stanford, CA 94305 (United States)

    2014-05-19

    We study a number of (3+1)- and (2+1)-dimensional defect and boundary conformal field theories holographically dual to supergravity theories. In all cases the defects or boundaries are planar, and the defects are codimension-one. Using holography, we compute the entanglement entropy of a (hemi-)spherical region centered on the defect (boundary). We define defect and boundary entropies from the entanglement entropy by an appropriate background subtraction. For some (3+1)-dimensional theories we find evidence that the defect/boundary entropy changes monotonically under certain renormalization group flows triggered by operators localized at the defect or boundary. This provides evidence that the g-theorem of (1+1)-dimensional field theories generalizes to higher dimensions.

  14. On holographic defect entropy

    Science.gov (United States)

    Estes, John; Jensen, Kristan; O'Bannon, Andy; Tsatis, Efstratios; Wrase, Timm

    2014-05-01

    We study a number of (3 + 1)- and (2 + 1)-dimensional defect and boundary conformal field theories holographically dual to supergravity theories. In all cases the defects or boundaries are planar, and the defects are codimension-one. Using holography, we compute the entanglement entropy of a (hemi-)spherical region centered on the defect (boundary). We define defect and boundary entropies from the entanglement entropy by an appropriate background subtraction. For some (3 + 1)-dimensional theories we find evidence that the defect/boundary entropy changes monotonically under certain renormalization group flows triggered by operators localized at the defect or boundary. This provides evidence that the g-theorem of (1 + 1)-dimensional field theories generalizes to higher dimensions.

  15. Detection of defects in tubes by ultrasonic techniques

    International Nuclear Information System (INIS)

    Hale, J.C.

    1982-01-01

    An ultrasonic technique is described for on-site detection of longitudinally extending defects in the heat exchange tubes of a sodium/water in-vessel heat exchanger. The method consists of directing ultrasonic beam energy along a chordal path into the inner wall surface of the tube to induce circumferentially extending shear waves in the wall and detecting the echo signals deflected from the defects. (U.K.)

  16. Modeling of Powder Bed Manufacturing Defects

    Science.gov (United States)

    Mindt, H.-W.; Desmaison, O.; Megahed, M.; Peralta, A.; Neumann, J.

    2018-01-01

    Powder bed additive manufacturing offers unmatched capabilities. The deposition resolution achieved is extremely high enabling the production of innovative functional products and materials. Achieving the desired final quality is, however, hampered by many potential defects that have to be managed in due course of the manufacturing process. Defects observed in products manufactured via powder bed fusion have been studied experimentally. In this effort we have relied on experiments reported in the literature and—when experimental data were not sufficient—we have performed additional experiments providing an extended foundation for defect analysis. There is large interest in reducing the effort and cost of additive manufacturing process qualification and certification using integrated computational material engineering. A prerequisite is, however, that numerical methods can indeed capture defects. A multiscale multiphysics platform is developed and applied to predict and explain the origin of several defects that have been observed experimentally during laser-based powder bed fusion processes. The models utilized are briefly introduced. The ability of the models to capture the observed defects is verified. The root cause of the defects is explained by analyzing the numerical results thus confirming the ability of numerical methods to provide a foundation for rapid process qualification.

  17. Defect production in ion-implanted yttria-stabilized zirconia investigated by positron depth profiling

    Energy Technology Data Exchange (ETDEWEB)

    Saude, S.; Grynszpan, R.I.; Anwand, W.; Brauer, G

    2004-11-17

    The presence and evolution of free-volume defects induced during ion-implantation in solids can be a critical issue in micro- and nano-technology processes. Using a slow positron beam and measuring the energy-line Doppler broadening (DB) of the annihilation radiation, sub-surface investigations were carried out on single crystals of yttria-fully stabilized zirconia (Y-FSZ), following implantation of 210 keV oxygen-ions at fluences ranging from 1.0 x 10{sup 13} to 2.5 x 10{sup 16} cm{sup -2}. Depth profiles of the DB-lineshape S reveal a defect peak at 60 % of the oxygen-ion projected range R{sub p}, i.e., closer to the surface than the vacancy distribution derived from Monte-Carlo calculations. The S-dependence on the fluence exhibits three defect-production stages already identified after implantation with noble gas ions. The intermediate stage (0.1-1 displacements per atom (dpa)) displays a trapping saturation plateau, which rises with increasing ion mass, suggesting a specific critical size for the relevant dominant defect. A slight drop in defect concentration that follows indicates that defects of the last stage (above 2 dpa), are formed at the expense of former ones. No particular effect due to the self-ion is found.

  18. Defects introduced by Ar plasma exposure in GaAs probed by monoenergetic positron beam

    Energy Technology Data Exchange (ETDEWEB)

    Uedono, Akira; Tanigawa, Shoichiro [Tsukuba Univ., Ibaraki (Japan). Inst. of Materials Science; Kawano, Takao; Wada, Kazumi; Nakanishi, Hideo

    1994-10-01

    Ar-plasma-induced defects in n-type GaAs were probed by a monoenergetic positron beam. The depth distribution of the defects was obtained from measurements of Doppler broadening profiles of the annihilation radiation as a function of incident positron energy. The damaged layer induced by the exposure was found to extend far beyond the stopping range of Ar ions, and the dominant defects were identified as interstitial-type defects. After 100degC annealing, such defects were annealed. Instead, vacancy-type defects were found to be the dominant defects in the subsurface region. (author).

  19. Silicone chain extender

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a silicone chain extender, more particularly a chain extender for silicone polymers and copolymers, to a chain extended silicone polymer or copolymer and to a functionalized chain extended silicone polymer or copolymer, to a method for the preparation thereof...

  20. Computational mask defect review for contamination and haze inspections

    Science.gov (United States)

    Morgan, Paul; Rost, Daniel; Price, Daniel; Corcoran, Noel; Satake, Masaki; Hu, Peter; Peng, Danping; Yonenaga, Dean; Tolani, Vikram; Wolf, Yulian; Shah, Pinkesh

    2013-09-01

    As optical lithography continues to extend into sub-0.35 k1 regime, mask defect inspection and subsequent review has become tremendously challenging, and indeed the largest component to mask manufacturing cost. The routine use of various resolution enhancement techniques (RET) have resulted in complex mask patterns, which together with the need to detect even smaller defects due to higher MEEFs, now requires an inspection engineer to use combination of inspection modes. This is achieved in 193nm AeraTM mask inspection systems wherein masks are not only inspected at their scanner equivalent aerial exposure conditions, but also at higher Numerical Aperture resolution, and special reflected-light, and single-die contamination modes, providing better coverage over all available patterns, and defect types. Once the required defects are detected by the inspection system, comprehensively reviewing and dispositioning each defect then becomes the Achilles heel of the overall mask inspection process. Traditionally, defects have been reviewed manually by an operator, which makes the process error-prone especially given the low-contrast in the convoluted aerial images. Such manual review also limits the quality and quantity of classifications in terms of the different types of characterization and number of defects that can practically be reviewed by a person. In some ways, such manual classification limits the capability of the inspection tool itself from being setup to detect smaller defects since it often results in many more defects that need to be then manually reviewed. Paper 8681-109 at SPIE Advanced Lithography 2013 discussed an innovative approach to actinic mask defect review using computational technology, and focused on Die-to-Die transmitted aerial and high-resolution inspections. In this approach, every defect is characterized in two different ways, viz., quantitatively in terms of its print impact on wafer, and qualitatively in terms of its nature and origin in

  1. Nanocarbon: Defect Architectures and Properties

    Science.gov (United States)

    Vuong, Amanda

    V6 hexavacancy variant, where six sp3 carbon atoms sit midway between two carbon layers and bond to both, is substantially more stable than any other vacancy aggregate in AA stacked layers. Chapter 5 presents the results of ab initio DFT calculations performed to investigate the wormhole and mezzanine defect that were identified in chapter 4 and the ramp defect discovered by Trevethan et al.. DFT calculations were performed on these defects in twisted bilayer graphene. From the investigation of vacancy complexes in twisted bilayer graphene, it is found that vacancy complexes are unstable in the twisted region and are more favourable in formation energy when the stacking arrangement is close to AA or AB stacking. It has also been discovered that the ramp defect is more stable in the twisted bilayer graphene compared to the mezzanine defect. Chapter 6 presents the results of ab initio DFT calculations performed to investigate a form of extending defect, prismatic edge dislocation. Suarez-Martinez et al.'s research suggest the armchair core is disconnected from any other layer, whilst the zigzag core is connected. In the investigation here, the curvature of the mezzanine defect allows it to swing between the armchair, zigzag and Klein in the AA stacking. For the AB stacking configuration, the armchair and zigzag core are connected from any other layer. Chapter 7 present results of MD simulations using the adaptive intermolecular reactive empirical bond order (AIREBO) potential to investigate the dimensional change of graphite due to the formation of vacancies present in a single crystal. It has been identified that there is an expansion along the c-axis, whilst a contraction along the a- and b- axes due to the coalescence of vacancy forming in-plane and between the layers. The results here are in good agreement with experimental studies of low temperature irradiation. The final chapter gives conclusions to this work.

  2. ILT based defect simulation of inspection images accurately predicts mask defect printability on wafer

    Science.gov (United States)

    Deep, Prakash; Paninjath, Sankaranarayanan; Pereira, Mark; Buck, Peter

    2016-05-01

    printability of defects at wafer level and automates the process of defect dispositioning from images captured using high resolution inspection machine. It first eliminates false defects due to registration, focus errors, image capture errors and random noise caused during inspection. For the remaining real defects, actual mask-like contours are generated using the Calibre® ILT solution [1][2], which is enhanced to predict the actual mask contours from high resolution defect images. It enables accurate prediction of defect contours, which is not possible from images captured using inspection machine because some information is already lost due to optical effects. Calibre's simulation engine is used to generate images at wafer level using scanner optical conditions and mask-like contours as input. The tool then analyses simulated images and predicts defect printability. It automatically calculates maximum CD variation and decides which defects are severe to affect patterns on wafer. In this paper, we assess the printability of defects for the mask of advanced technology nodes. In particular, we will compare the recovered mask contours with contours extracted from SEM image of the mask and compare simulation results with AIMSTM for a variety of defects and patterns. The results of printability assessment and the accuracy of comparison are presented in this paper. We also suggest how this method can be extended to predict printability of defects identified on EUV photomasks.

  3. Defects in semiconductors

    CERN Document Server

    Romano, Lucia; Jagadish, Chennupati

    2015-01-01

    This volume, number 91 in the Semiconductor and Semimetals series, focuses on defects in semiconductors. Defects in semiconductors help to explain several phenomena, from diffusion to getter, and to draw theories on materials' behavior in response to electrical or mechanical fields. The volume includes chapters focusing specifically on electron and proton irradiation of silicon, point defects in zinc oxide and gallium nitride, ion implantation defects and shallow junctions in silicon and germanium, and much more. It will help support students and scientists in their experimental and theoret

  4. Intrinsic Defects and H Doping in WO3

    KAUST Repository

    Zhu, Jiajie

    2017-01-18

    WO3 is widely used as industrial catalyst. Intrinsic and/or extrinsic defects can tune the electronic properties and extend applications to gas sensors and optoelectonics. However, H doping is a challenge to WO3, the relevant mechanisms being hardly understood. In this context, we investigate intrinsic defects and H doping by density functional theory and experiments. Formation energies are calculated to determine the lowest energy defect states. O vacancies turn out to be stable in O-poor environment, in agreement with X-ray photoelectron spectroscopy, and O-H bond formation of H interstitial defects is predicted and confirmed by Fourier transform infrared spectroscopy.

  5. GaN: Defect and Device Issues

    Energy Technology Data Exchange (ETDEWEB)

    Pearton, S.J.; Ren, F.; Shul, R.J.; Zolper, J.C.

    1998-11-09

    The role of extended and point defects, and key impurities such as C, O and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

  6. Effect of structural defects on the thermal conductivity of graphene: From point to line defects to haeckelites

    Science.gov (United States)

    Fthenakis, Zacharias G.; Zhu, Zhen; Tománek, David

    2014-03-01

    We use nonequilibrium molecular-dynamics simulations to study the effect of structural defects on the thermal conductivity λ of graphene. Focusing on 5-7 and 5-8 defects in the graphene honeycomb lattice, we find that λ depends sensitively on whether the defects are isolated, form lines, or form extended arrangements in haeckelites. Our results indicate that the presence of defects makes λ anisotropic and, depending on the temperature, quenches its value by one to two orders of magnitude with respect to graphene, mainly by reducing the phonon mean free path.

  7. Defects in hardwood timber

    Science.gov (United States)

    Roswell D. Carpenter; David L. Sonderman; Everette D. Rast; Martin J. Jones

    1989-01-01

    Includes detailed information on all common defects that may aRect hardwood trees and logs. Relationships between manufactured products and those forms of round material to be processed from the tree for conversion into marketable products are discussed. This handbook supersedes Agriculture Handbook No. 244, Grade defects in hardwood timber and logs, by C.R. Lockard, J...

  8. Craniotomy Frontal Bone Defect

    African Journals Online (AJOL)

    2018-03-01

    Mar 1, 2018 ... with cosmetic deformity of fore head (Figure 1), and he claimed that he could not get job because of ... 1: Pre-operative forontal view of patient. Figure 2: Intra operative photography of defect (A) reconstructed defect (B) ... with a cosmetic deformity of forehead on left side. (4nA and B). He was a candidate for.

  9. Defects at oxide surfaces

    CERN Document Server

    Thornton, Geoff

    2015-01-01

    This book presents the basics and characterization of defects at oxide surfaces. It provides a state-of-the-art review of the field, containing information to the various types of surface defects, describes analytical methods to study defects, their chemical activity and the catalytic reactivity of oxides. Numerical simulations of defective structures complete the picture developed. Defects on planar surfaces form the focus of much of the book, although the investigation of powder samples also form an important part. The experimental study of planar surfaces opens the possibility of applying the large armoury of techniques that have been developed over the last half-century to study surfaces in ultra-high vacuum. This enables the acquisition of atomic level data under well-controlled conditions, providing a stringent test of theoretical methods. The latter can then be more reliably applied to systems such as nanoparticles for which accurate methods of characterization of structure and electronic properties ha...

  10. Extended Enterprise performance Management

    NARCIS (Netherlands)

    Bobbink, Maria Lammerdina; Hartmann, Andreas

    2014-01-01

    The allegiance of partnering organisations and their employees to an Extended Enterprise performance is its proverbial sword of Damocles. Literature on Extended Enterprises focuses on collaboration, inter-organizational integration and learning to avoid diminishing or missing allegiance becoming an

  11. Defect reaction network in Si-doped InAs. Numerical predictions.

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, Peter A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-05-01

    This Report characterizes the defects in the def ect reaction network in silicon - doped, n - type InAs predicted with first principles density functional theory. The reaction network is deduced by following exothermic defect reactions starting with the initially mobile interstitial defects reacting with common displacement damage defects in Si - doped InAs , until culminating in immobile reaction p roducts. The defect reactions and reaction energies are tabulated, along with the properties of all the silicon - related defects in the reaction network. This Report serves to extend the results for the properties of intrinsic defects in bulk InAs as colla ted in SAND 2013 - 2477 : Simple intrinsic defects in InAs : Numerical predictions to include Si - containing simple defects likely to be present in a radiation - induced defect reaction sequence . This page intentionally left blank

  12. Syndrome of extended shadow

    International Nuclear Information System (INIS)

    Ginzburg, M.A.

    1987-01-01

    Syndrome of extended shadow is characterized by large (more than one lobe) or total shadow of the lung area. A detailed roentgenological characteristic and intrasyndrome differential diagnosis of extended shadows is given. Ethiology, pathogenesis and pathomorphology as well as clinical picture and methods of investigation of extended shadows are discussed

  13. Perspectives on extended Deterrence

    International Nuclear Information System (INIS)

    Tertrais, Bruno; Yost, David S.; Bunn, Elaine; Lee, Seok-soo; Levite, Ariel e.; Russell, James A.; Hokayem, Emile; Kibaroglu, Mustafa; Schulte, Paul; Thraenert, Oliver; Kulesa, Lukasz

    2010-05-01

    In November 2009, the Foundation for Strategic Research (Fondation pour la recherche strategique, FRS) convened a workshop on 'The Future of extended Deterrence', which included the participation of some of the best experts of this topic, from the United States, Europe, the Middle East and East Asia, as well as French and NATO officials. This document brings together the papers prepared for this seminar. Several of them were updated after the publication in April 2010 of the US Nuclear Posture Review. The seminar was organized with the support of the French Atomic energy Commission (Commissariat a l'energie atomique - CEA). Content: 1 - The future of extended deterrence: a brainstorming paper (Bruno Tertrais); 2 - US extended deterrence in NATO and North-East Asia (David S. Yost); 3 - The future of US extended deterrence (Elaine Bunn); 4 - The future of extended deterrence: a South Korean perspective (Seok-soo Lee); 5 - Reflections on extended deterrence in the Middle East (Ariel e. Levite); 6 - extended deterrence, security guarantees and nuclear weapons: US strategic and policy conundrums in the Gulf (James A. Russell); 7 - extended deterrence in the Gulf: a bridge too far? (Emile Hokayem); 8 - The future of extended deterrence: the case of Turkey (Mustafa Kibaroglu); 9 - The future of extended deterrence: a UK view (Paul Schulte); 10 - NATO and extended deterrence (Oliver Thraenert); 11 - extended deterrence and assurance in Central Europe (Lukasz Kulesa)

  14. Conductivity of epitaxial and CVD graphene with correlated line defects

    DEFF Research Database (Denmark)

    Radchenko, T. M.; Shylau, Artsem; Zozoulenko, I. V.

    2014-01-01

    -type scattering potential. The dc conductivity is calculated numerically for different cases of distribution of line defects. This includes a random (uncorrelated) and a correlated distribution with a prevailing direction in the orientation of lines. The anisotropy of the conductivity along and across the line...... defects is revealed, which agrees with experimental measurements for epitaxial graphene grown on SiC. We performed a detailed study of the conductivity for different defect correlations, introducing the correlation angle αmax-the maximum possible angle between any two lines. We find that for a given...... electron density, the relative enhancement of the conductivity for the case of fully correlated line defects in comparison to the case of uncorrelatecl ones is larger for a higher defect density. Finally, we, for the first time, study the conductivity of realistic samples where both extended line defects...

  15. Screening Tests for Birth Defects

    Science.gov (United States)

    ... Advocacy For Patients About ACOG Screening Tests for Birth Defects Home For Patients Search FAQs Screening Tests ... FAQ165, April 2014 PDF Format Screening Tests for Birth Defects Pregnancy What is a birth defect? What ...

  16. Single Ventricle Defects

    Science.gov (United States)

    ... heart defects along with pulmonary atresia. (Children with tetralogy of Fallot who also have pulmonary atresia may have treatment similar to others with tetralogy of Fallot.) How does it affect the heart? An opening ...

  17. Repairing Nanoparticle Surface Defects

    NARCIS (Netherlands)

    Marino, Emanuele; Kodger, Thomas E.; Crisp, R.W.; Timmerman, Dolf; MacArthur, Katherine E.; Heggen, Marc; Schall, Peter

    2017-01-01

    Solar devices based on semiconductor nanoparticles require the use of conductive ligands; however, replacing the native, insulating ligands with conductive metal chalcogenide complexes introduces structural defects within the crystalline nanostructure that act as traps for charge carriers. We

  18. Neural tube defects

    Directory of Open Access Journals (Sweden)

    M.E. Marshall

    1981-09-01

    Full Text Available Neural tube defects refer to any defect in the morphogenesis of the neural tube, the most common types being spina bifida and anencephaly. Spina bifida has been recognised in skeletons found in north-eastern Morocco and estimated to have an age of almost 12 000 years. It was also known to the ancient Greek and Arabian physicians who thought that the bony defect was due to the tumour. The term spina bifida was first used by Professor Nicolai Tulp of Amsterdam in 1652. Many other terms have been used to describe this defect, but spina bifida remains the most useful general term, as it describes the separation of the vertebral elements in the midline.

  19. [Skin defect modeling in experimental animals].

    Science.gov (United States)

    Oleshko, A N; Kornienko, V V; Tkachenko, Yu A; Kurganskaya, V A

    2015-02-01

    To assess the skin regeneration and explore new medical devices for the treatment of skin defects is necessary to conduct long-term experiments using laboratory animals. Currently, there are many methods for skin trauma modeling but most of them have disadvantages that limit their use. The purpose of this work - the development of an experimental model of the formation of skin defect of various etiologies with the specified parameters of depth and area of damage to the absence of systemic effects on the animal's body. We have developed an installation that allows us to form a skin defect of mechanical, thermal and chemical etiology with area from 1.76 cm2 to 2.0 cm2. The experiment was conducted on 18 male laboratory rats to examine the effectiveness of current method and control the depth and area of the defect. As a result of the new methodology, we were able to carry out simulation skin injuries of different etiology on laboratory animals in the short term and reduce the severity of injuries to extend the life span of animals to monitor the repair processes, as well as to standardize the modeling of injuries according to the criteria of area and depth of the defect.

  20. Extended icosahedral structures

    CERN Document Server

    Jaric, Marko V

    1989-01-01

    Extended Icosahedral Structures discusses the concepts about crystal structures with extended icosahedral symmetry. This book is organized into six chapters that focus on actual modeling of extended icosahedral crystal structures. This text first presents a tiling approach to the modeling of icosahedral quasiperiodic crystals. It then describes the models for icosahedral alloys based on random connections between icosahedral units, with particular emphasis on diffraction properties. Other chapters examine the glassy structures with only icosahedral orientational order and the extent of tra

  1. Extending Database Integration Technology

    National Research Council Canada - National Science Library

    Buneman, Peter

    1999-01-01

    Formal approaches to the semantics of databases and database languages can have immediate and practical consequences in extending database integration technologies to include a vastly greater range...

  2. Extended Life Coolant Testing

    Science.gov (United States)

    2016-06-06

    military vehicles. Newer vehicles come factory- filled with ELC, while the Army continues to use traditional supplemental coolant additives (SCA)-based...UNCLASSIFIED TABLE OF CONTENTS EXTENDED LIFE COOLANT TESTING INTERIM REPORT TFLRF No. 478 by Gregory A. T. Hansen Edwin A...longer needed. Do not return it to the originator. UNCLASSIFIED UNCLASSIFIED EXTENDED LIFE COOLANT TESTING INTERIM REPORT TFLRF No

  3. Extended Theories of Gravitation

    Directory of Open Access Journals (Sweden)

    Fatibene Lorenzo

    2013-09-01

    Full Text Available Extended theories of gravitation are naturally singled out by an analysis inspired by the Ehelers-Pirani-Schild framework. In this framework the structure of spacetime is described by a Weyl geometry which is enforced by dynamics. Standard General Relativity is just one possible theory within the class of extended theories of gravitation. Also all Palatini f(R theories are shown to be extended theories of gravitation. This more general setting allows a more general interpretation scheme and more general possible couplings between gravity and matter. The definitions and constructions of extended theories will be reviewed. A general interpretation scheme will be considered for extended theories and some examples will be considered.

  4. Channelling radiation and applications to defects in solids

    International Nuclear Information System (INIS)

    Pathak, A.P.

    1984-06-01

    Using one and two-dimensional hydrogen atom models (with quantum defect corrections) for planar and axial channelling of electrons and harmonic oscillator models in one and two-dimensions for planar and axial cases (with anharmonicity corrections) for positron channelling, some analytical results have been obtained for channelling radiation frequencies. The effects of extended defects (like dislocations) are then considered qualitatively. Some quantitative results are also obtained. (author)

  5. Extended family medicine training

    Science.gov (United States)

    Slade, Steve; Ross, Shelley; Lawrence, Kathrine; Archibald, Douglas; Mackay, Maria Palacios; Oandasan, Ivy F.

    2016-01-01

    Abstract Objective To examine trends in family medicine training at a time when substantial pedagogic change is under way, focusing on factors that relate to extended family medicine training. Design Aggregate-level secondary data analysis based on the Canadian Post-MD Education Registry. Setting Canada. Participants All Canadian citizens and permanent residents who were registered in postgraduate family medicine training programs within Canadian faculties of medicine from 1995 to 2013. Main outcome measures Number and proportion of family medicine residents exiting 2-year and extended (third-year and above) family medicine training programs, as well as the types and numbers of extended training programs offered in 2015. Results The proportion of family medicine trainees pursuing extended training almost doubled during the study period, going from 10.9% in 1995 to 21.1% in 2013. Men and Canadian medical graduates were more likely to take extended family medicine training. Among the 5 most recent family medicine exit cohorts (from 2009 to 2013), 25.9% of men completed extended training programs compared with 18.3% of women, and 23.1% of Canadian medical graduates completed extended training compared with 13.6% of international medical graduates. Family medicine programs vary substantially with respect to the proportion of their trainees who undertake extended training, ranging from a low of 12.3% to a high of 35.1% among trainees exiting from 2011 to 2013. Conclusion New initiatives, such as the Triple C Competency-based Curriculum, CanMEDS–Family Medicine, and Certificates of Added Competence, have emerged as part of family medicine education and credentialing. In acknowledgment of the potential effect of these initiatives, it is important that future research examine how pedagogic change and, in particular, extended training shapes the care family physicians offer their patients. As part of that research it will be important to measure the breadth and uptake of

  6. Point defects in lines in single crystalline phosphorene: directional migration and tunable band gaps.

    Science.gov (United States)

    Li, Xiuling; Ma, Liang; Wang, Dayong; Zeng, Xiao Cheng; Wu, Xiaojun; Yang, Jinlong

    2016-10-20

    Extended line defects in two-dimensional (2D) materials can play an important role in modulating their electronic properties. During the experimental synthesis of 2D materials, line defects are commonly generated at grain boundaries between domains of different orientations. In this work, twelve types of line-defect structures in single crystalline phosphorene are examined by using first-principles calculations. These line defects are typically formed via migration and aggregation of intrinsic point defects, including the Stone-Wales (SW), single or double vacancy (SV or DV) defects. Our calculated results demonstrate that the migration of point defects in phosphorene is anisotropic, for instance, the lowest migration energy barriers are 1.39 (or 0.40) and 2.58 (or 0.49) eV for SW (or SV) defects in zigzag and armchair directions, respectively. The aggregation of point defects into lines is energetically favorable compared with the separated point defects in phosphorene. In particular, the axis of line defects in phosphorene is direction-selective, depending on the composed point defects. The presence of line defects effectively modulates the electronic properties of phosphorene, rendering the defect-containing phosphorene either metallic or semiconducting with a tunable band gap. Of particular interest is the fact that the SV-based line defect can behave as a metallic wire, suggesting a possibility to fabricate a circuit with subnanometer widths in the semiconducting phosphorene for nanoscale electronic application.

  7. DEFECTS SIMULATION OF ROLLING STRIP

    OpenAIRE

    Rudolf Mišičko; Tibor Kvačkaj; Martin Vlado; Lucia Gulová; Miloslav Lupták; Jana Bidulská

    2009-01-01

    The defects in the continuous casting slabs can be developed or kept down in principle by rolling technology, especially depend to sort, size and distribution of primary defects, as well as used of rolling parameters. Scope of the article is on observation behavior artificial surface and undersurface defects (scores) without filler (surface defects) and filling by oxides and casting powder (subsurface defects). First phase of hot rolling process have been done by software simulation DEFORM 3D...

  8. Quantum computing with defects

    Science.gov (United States)

    Varley, Joel

    2011-03-01

    The development of a quantum computer is contingent upon the identification and design of systems for use as qubits, the basic units of quantum information. One of the most promising candidates consists of a defect in diamond known as the nitrogen-vacancy (NV-1) center, since it is an individually-addressable quantum system that can be initialized, manipulated, and measured with high fidelity at room temperature. While the success of the NV-1 stems from its nature as a localized ``deep-center'' point defect, no systematic effort has been made to identify other defects that might behave in a similar way. We provide guidelines for identifying other defect centers with similar properties. We present a list of physical criteria that these centers and their hosts should meet and explain how these requirements can be used in conjunction with electronic structure theory to intelligently sort through candidate systems. To elucidate these points, we compare electronic structure calculations of the NV-1 center in diamond with those of several deep centers in 4H silicon carbide (SiC). Using hybrid functionals, we report formation energies, configuration-coordinate diagrams, and defect-level diagrams to compare and contrast the properties of these defects. We find that the NC VSi - 1 center in SiC, a structural analog of the NV-1 center in diamond, may be a suitable center with very different optical transition energies. We also discuss how the proposed criteria can be translated into guidelines to discover NV analogs in other tetrahedrally coordinated materials. This work was performed in collaboration with J. R. Weber, W. F. Koehl, B. B. Buckley, A. Janotti, C. G. Van de Walle, and D. D. Awschalom. This work was supported by ARO, AFOSR, and NSF.

  9. Structure defects in cementite

    International Nuclear Information System (INIS)

    Schmitt, Bernard

    1971-01-01

    After a presentation of experimental techniques (elaboration principles, elaboration techniques, and investigation techniques for cementite thin layers and iron-carbon massive alloys), the author of this research thesis reports the study of cementite structure (interatomic distance, description and representation), reports the study of iron-carbon thin layers (structure, influence of silicon, defects), reports the study of perfect and imperfect dislocations and of plane defects in cementite. The author also reports hardness measurements, and discusses the relationships between cementite and other iron carbides

  10. The Extended Enterprise concept

    DEFF Research Database (Denmark)

    Larsen, Lars Bjørn; Vesterager, Johan; Gobbi, Chiara

    1999-01-01

    This paper provides an overview of the work that has been done regarding the Extended Enterprise concept in the Common Concept team of Globeman 21 including references to results deliverables concerning the development of the Extended Enterprise concept. The first section presents the basic concept...... picture from Globeman21, which illustrates the Globeman21 way of realising the Extended Enterprise concept. The second section presents the Globeman21 EE concept in a life cycle perspective, which to a large extent is based on the thoughts and ideas behind GERAM (ISO/DIS 15704)....

  11. Building Extended Families

    Science.gov (United States)

    McKain, Barbara; McKain, Michael

    1970-01-01

    Discusses need for dissolution of the couple" relationship with substitution of the extended family which would permit each member to maintain individuality and to function on own merit. Suggests group living as preferable alternative. (CJ)

  12. Extending mine life

    International Nuclear Information System (INIS)

    Anon.

    1984-01-01

    Mine layouts, new machines and techniques, research into problem areas of ground control and so on, are highlighted in this report on extending mine life. The main resources taken into account are coal mining, uranium mining, molybdenum and gold mining

  13. Rational extended thermodynamics

    CERN Document Server

    Müller, Ingo

    1998-01-01

    Ordinary thermodynamics provides reliable results when the thermodynamic fields are smooth, in the sense that there are no steep gradients and no rapid changes. In fluids and gases this is the domain of the equations of Navier-Stokes and Fourier. Extended thermodynamics becomes relevant for rapidly varying and strongly inhomogeneous processes. Thus the propagation of high­ frequency waves, and the shape of shock waves, and the regression of small-scale fluctuation are governed by extended thermodynamics. The field equations of ordinary thermodynamics are parabolic while extended thermodynamics is governed by hyperbolic systems. The main ingredients of extended thermodynamics are • field equations of balance type, • constitutive quantities depending on the present local state and • entropy as a concave function of the state variables. This set of assumptions leads to first order quasi-linear symmetric hyperbolic systems of field equations; it guarantees the well-posedness of initial value problems and f...

  14. Quantum computing with defects.

    Science.gov (United States)

    Weber, J R; Koehl, W F; Varley, J B; Janotti, A; Buckley, B B; Van de Walle, C G; Awschalom, D D

    2010-05-11

    Identifying and designing physical systems for use as qubits, the basic units of quantum information, are critical steps in the development of a quantum computer. Among the possibilities in the solid state, a defect in diamond known as the nitrogen-vacancy (NV(-1)) center stands out for its robustness--its quantum state can be initialized, manipulated, and measured with high fidelity at room temperature. Here we describe how to systematically identify other deep center defects with similar quantum-mechanical properties. We present a list of physical criteria that these centers and their hosts should meet and explain how these requirements can be used in conjunction with electronic structure theory to intelligently sort through candidate defect systems. To illustrate these points in detail, we compare electronic structure calculations of the NV(-1) center in diamond with those of several deep centers in 4H silicon carbide (SiC). We then discuss the proposed criteria for similar defects in other tetrahedrally coordinated semiconductors.

  15. Defects in semiconductor nanostructures

    Indian Academy of Sciences (India)

    sizes were less than 100 Si atoms due to computational limitations. An interesting parallel is that current first principles calculations alluded to in §5 are size ham- pered for similar reasons. These 'defect molecule' calculations were probably the first studies in SN. We believe that a perusal of this 'ancient' scientific literature.

  16. Production of point defects

    International Nuclear Information System (INIS)

    Zuppiroli, L.

    1975-01-01

    Vacancies at thermodynamic equilibrium and the annealing of these defects are studied first, after which electron irradiations are dealt with. The displacement threshold energy concept is introduced. Part three concerns heavy ion and neutron irradiations. Displacement cascades and the thermal spike concept are discussed [fr

  17. Fetal abdominal wall defects.

    Science.gov (United States)

    Prefumo, Federico; Izzi, Claudia

    2014-04-01

    The most common fetal abdominal wall defects are gastroschisis and omphalocele, both with a prevalence of about three in 10,000 births. Prenatal ultrasound has a high sensitivity for these abnormalities already at the time of the first-trimester nuchal scan. Major unrelated defects are associated with gastroschisis in about 10% of cases, whereas omphalocele is associated with chromosomal or genetic abnormalities in a much higher proportion of cases. Challenges in management of gastroschisis are related to the prevention of late intrauterine death, and the prediction and treatment of complex forms. With omphalocele, the main difficulty is the exclusion of associated conditions, not all diagnosed prenatally. An outline of the postnatal treatment of abdominal wall defects is given. Other rarer forms of abdominal wall defects are pentalogy of Cantrell, omphalocele, bladder exstrophy, imperforate anus, spina bifida complex, prune-belly syndrome, body stalk anomaly, and bladder and cloacal exstrophy; they deserve multidisciplinary counselling and management. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Defects in flexoelectric solids

    Science.gov (United States)

    Mao, Sheng; Purohit, Prashant K.

    2015-11-01

    A solid is said to be flexoelectric when it polarizes in proportion to strain gradients. Since strain gradients are large near defects, we expect the flexoelectric effect to be prominent there and decay away at distances much larger than a flexoelectric length scale. Here, we quantify this expectation by computing displacement, stress and polarization fields near defects in flexoelectric solids. For point defects we recover some well known results from strain gradient elasticity and non-local piezoelectric theories, but with different length scales in the final expressions. For edge dislocations we show that the electric potential is a maximum in the vicinity of the dislocation core. We also estimate the polarized line charge density of an edge dislocation in an isotropic flexoelectric solid which is in agreement with some measurements in ice. We perform an asymptotic analysis of the crack tip fields in flexoelectric solids and show that our results share some features from solutions in strain gradient elasticity and piezoelectricity. We also compute the energy release rate for cracks using simple crack face boundary conditions and use them in classical criteria for crack growth to make predictions. Our analysis can serve as a starting point for more sophisticated analytic and computational treatments of defects in flexoelectric solids which are gaining increasing prominence in the field of nanoscience and nanotechnology.

  19. Semiconductor Nanowires: Defects Update

    Science.gov (United States)

    Kavanagh, Karen L.

    2008-05-01

    Structural defects commonly observed in semiconducting nanowires by electron microscopy will be reviewed and their origins discussed. Their effects on electrical and optical properties will be illustrated with examples from GaSb, InAs, and ZnSe nanowires grown by MOCVD and MBE.

  20. First-principles analysis of defect-mediated Li adsorption on graphene.

    Science.gov (United States)

    Yildirim, Handan; Kinaci, Alper; Zhao, Zhi-Jian; Chan, Maria K Y; Greeley, Jeffrey P

    2014-12-10

    To evaluate the possible utility of single layer graphene for applications in Li ion batteries, an extensive series of periodic density functional theory (DFT) calculations are performed on graphene sheets with both point and extended defects for a wide range of lithium coverages. Consistent with recent reports, it is found that Li adsorption on defect-free single layer graphene is not thermodynamically favorable compared to bulk metallic Li. However, graphene surfaces activated by defects are generally found to bind Li more strongly, and the interaction strength is sensitive to both the nature of the defects and their densities. Double vacancy defects are found to have much stronger interactions with Li as compared to Stone-Wales defects, and increasing defect density also enhances the interaction of the Stone-Wales defects with Li. Li interaction with one-dimensional extended defects on graphene is additionally found to be strong and leads to increased Li adsorption. A rigorous thermodynamic analysis of these data establishes the theoretical Li storage capacities of the defected graphene structures. In some cases, these capacities are found to approach, although not exceed, those of graphite. The results provide new insights into the fundamental physics of adsorbate interactions with graphene defects and suggest that careful defect engineering of graphene might, ultimately, provide anode electrodes of suitable capacity for lithium ion battery applications.

  1. Electronic structure of defects in semiconductor heterojunctions

    International Nuclear Information System (INIS)

    Haussy, Bernard; Ganghoffer, Jean Francois

    2002-01-01

    Full text.heterojunctions and semiconductors and superlattices are well known and well used by people interested in optoelectronics communications. Components based on the use of heterojunctions are interesting for confinement of light and increase of quantum efficiency. An heterojunction is the contact zone between two different semiconductors, for example GaAs and Ga 1-x Al x As. Superlattices are a succession of heterojunctions (up to 10 or 20). These systems have been the subjects of many experiments ao analyse the contact between semiconductors. They also have been theoretically studied by different types of approach. The main result of those studies is the prediciton of band discontinuities. Defects in heterojunctions are real traps for charge carriers; they can affect the efficiency of the component decreasing the currents and the fluxes in it. the knowledge of their electronic structure is important, a great density of defects deeply modifies the electronic structure of the whole material creating real new bands of energy in the band structure of the component. in the first part of this work, we will describe the heterostructure and the defect in terms of quantum wells and discrete levels. This approach allows us to show the role of the width of the quantum well describing the structure but induces specific behaviours due to the one dimensional modelling. Then a perturbative treatment is proposed using the Green's functions formalism. We build atomic chains with different types of atoms featuring the heterostructure and the defect. Densities of states of a structure with a defect and levels associated to the defect are obtained. Results are comparable with the free electrons work, but the modelling do not induce problems due to a one dimensional approach. To extend our modelling, a three dimensions approach, based on a cavity model, is investigated. The influence of the defect, - of hydrogenoid type - introduced in the structure, is described by a cavity

  2. Extending quantum mechanics entails extending special relativity

    International Nuclear Information System (INIS)

    Aravinda, S; Srikanth, R

    2016-01-01

    The complementarity between signaling and randomness in any communicated resource that can simulate singlet statistics is generalized by relaxing the assumption of free will in the choice of measurement settings. We show how to construct an ontological extension for quantum mechanics (QMs) through the oblivious embedding of a sound simulation protocol in a Newtonian spacetime. Minkowski or other intermediate spacetimes are ruled out as the locus of the embedding by virtue of hidden influence inequalities. The complementarity transferred from a simulation to the extension unifies a number of results about quantum non-locality, and implies that special relativity has a different significance for the ontological model and for the operational theory it reproduces. Only the latter, being experimentally accessible, is required to be Lorentz covariant. There may be certain Lorentz non-covariant elements at the ontological level, but they will be inaccessible at the operational level in a valid extension. Certain arguments against the extendability of QM, due to Conway and Kochen (2009) and Colbeck and Renner (2012), are attributed to their assumption that the spacetime at the ontological level has Minkowski causal structure. (paper)

  3. Extraction of fetal electrocardiogram (ECG) by extended state ...

    Indian Academy of Sciences (India)

    Fetal electrocardiogram (ECG) gives information about the health status of fetus and so, an early diagnosis of any cardiac defect before delivery increases the effectiveness of appropriate treatment. In this paper, authors investigate the use of adaptive neuro-fuzzy inference system (ANFIS) with extended Kalman filter for fetal ...

  4. Ventricular Septal Defect (For Teens)

    Science.gov (United States)

    ... have a heart defect should avoid getting body piercings. Piercing increases the possibility that bacteria can get into ... damage heart valves. If you're considering a piercing and you have a heart defect, talk to ...

  5. Congenital Heart Defects (For Parents)

    Science.gov (United States)

    ... diagnosed until the teen years — or even adulthood. Newborn Screening Newborns in the U.S. are screened at ... Has a Heart Defect Coarctation of the Aorta Arrhythmias Mitral Valve Prolapse Atrial Septal Defect Ventricular Septal ...

  6. Defects in Quantum Computers.

    Science.gov (United States)

    Gardas, Bartłomiej; Dziarmaga, Jacek; Zurek, Wojciech H; Zwolak, Michael

    2018-03-14

    The shift of interest from general purpose quantum computers to adiabatic quantum computing or quantum annealing calls for a broadly applicable and easy to implement test to assess how quantum or adiabatic is a specific hardware. Here we propose such a test based on an exactly solvable many body system-the quantum Ising chain in transverse field-and implement it on the D-Wave machine. An ideal adiabatic quench of the quantum Ising chain should lead to an ordered broken symmetry ground state with all spins aligned in the same direction. An actual quench can be imperfect due to decoherence, noise, flaws in the implemented Hamiltonian, or simply too fast to be adiabatic. Imperfections result in topological defects: Spins change orientation, kinks punctuating ordered sections of the chain. The number of such defects quantifies the extent by which the quantum computer misses the ground state, and is, therefore, imperfect.

  7. Reconstructions of eyelid defects

    Directory of Open Access Journals (Sweden)

    Nirmala Subramanian

    2011-01-01

    Full Text Available Eyelids are the protective mechanism of the eyes. The upper and lower eyelids have been formed for their specific functions by Nature. The eyelid defects are encountered in congenital anomalies, trauma, and postexcision for neoplasm. The reconstructions should be based on both functional and cosmetic aspects. The knowledge of the basic anatomy of the lids is a must. There are different techniques for reconstructing the upper eyelid, lower eyelid, and medial and lateral canthal areas. Many a times, the defects involve more than one area. For the reconstruction of the lid, the lining should be similar to the conjunctiva, a cover by skin and the middle layer to give firmness and support. It is important to understand the availability of various tissues for reconstruction. One layer should have the vascularity to support the other layer which can be a graft. A proper plan and execution of it is very important.

  8. Defects and Rearrangements in Disordered Solids

    Science.gov (United States)

    Wijtmans, Sven

    In this thesis, I will investigate the properties of disordered materials under strain. Disordered materials encompass a large variety of materials, including glasses, polymers, granular matter, dense colloids, and gels. There is currently no constitutive equation based on microscopic observables that describes these materials. Given the prevalence and usefulness of these materials, we derive tools to aid our understanding of them. We develop a new method to isolate localized defects from extended vibrational modes in disordered solids. This method augments particle interactions with an artificial potential that acts as a high-pass filter: it preserves small-scale structures while pushing extended vibrational modes to higher frequencies. The low-frequency modes that remain are ``bare" defects; they are exponentially localized without the quadrupolar tails associated with elastic interactions. We demonstrate that these localized excitations are excellent predictors of plastic rearrangements in the solid. We characterize several of the properties of these defects that appear in mesoscopic theories of plasticity, including their distribution of energy barriers, number density, and size, which is a first step in testing and revising continuum models for plasticity in disordered solids. We additionally study the properties of rearrangement types in 2D disordered packings of particles with a harmonic potential at a range of packing fractions above jamming. We develop a generalizable procedure that classifies events by stress drop, energy drop, and reversibility under two protocols. Somewhat surprisingly, we find a large population of contact change events that have no associated stress drop. Reversible events become more common at high pressures above a packing fraction of phi=0.865, at which point line reversible events are more common than loop reversible events. At low pressures, irreversible events are associated with spatially extended events, while at high

  9. An Extended Duopoly Game.

    Science.gov (United States)

    Eckalbar, John C.

    2002-01-01

    Illustrates how principles and intermediate microeconomic students can gain an understanding for strategic price setting by playing a relatively large oligopoly game. Explains that the game extends to a continuous price space and outlines appropriate applications. Offers the Mathematica code to instructors so that the assumptions of the game can…

  10. Extending Critical Performativity

    DEFF Research Database (Denmark)

    Spicer, André; Alvesson, Mats; Kärreman, Dan

    2016-01-01

    from an undue focus on intra-academic debates; engage in author-itarian theoretical policing; feign relevance through symbolic radicalism; and repackage common sense. We take these critiques as an opportunity to offer an extended model of critical performativity that involves focusing on issues...

  11. Parameterization of extended systems

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik

    2006-01-01

    The YJBK parameterization (of all stabilizing controllers) is extended to handle systems with additional sensors and/or actuators. It is shown that the closed loop transfer function is still an affine function in the YJBK parameters in the nominal case. Further, some closed-loop stability results...

  12. Poster Session- Extended Abstracts

    Science.gov (United States)

    Jack D. Alexander III; Jean Findley; Brenda K. Kury; Jan L. Beyers; Douglas S. Cram; Terrell T. Baker; Jon C. Boren; Carl Edminster; Sue A. Ferguson; Steven McKay; David Nagel; Trent Piepho; Miriam Rorig; Casey Anderson; Jeanne Hoadley; Paulette L. Ford; Mark C. Andersen; Ed L. Fredrickson; Joe Truett; Gary W. Roemer; Brenda K. Kury; Jennifer Vollmer; Christine L. May; Danny C. Lee; James P. Menakis; Robert E. Keane; Zhi-Liang Zhu; Carol Miller; Brett Davis; Katharine Gray; Ken Mix; William P. Kuvlesky Jr.; D. Lynn Drawe; Marcia G. Narog; Roger D. Ottmar; Robert E. Vihnanek; Clinton S. Wright; Timothy E. Paysen; Burton K. Pendleton; Rosemary L. Pendleton; Carleton S. White; John Rogan; Doug Stow; Janet Franklin; Jennifer Miller; Lisa Levien; Chris Fischer; Emma Underwood; Robert Klinger; Peggy Moore; Clinton S. Wright

    2008-01-01

    Titles found within Poster Session-Extended Abstracts include:Assessment of emergency fire rehabilitation of four fires from the 2000 fire season on the Vale, Oregon, BLM district: review of the density sampling materials and methods: p. 329 Growth of regreen, seeded for erosion control, in the...

  13. Benign gastric filling defect

    Energy Technology Data Exchange (ETDEWEB)

    Oh, K. K.; Lee, Y. H.; Cho, O. K.; Park, C. Y. [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    1979-06-15

    The gastric lesion is a common source of complaints to Orientals, however, evaluation of gastric symptoms and laboratory examination offer little specific aid in the diagnosis of gastric diseases. Thus roentgenography of gastrointestinal tract is one of the most reliable method for detail diagnosis. On double contract study of stomach, gastric filling defect is mostly caused by malignant gastric cancer, however, other benign lesions can cause similar pictures which can be successfully treated by surgery. 66 cases of benign causes of gastric filling defect were analyzed at this point of view, which was verified pathologically by endoscope or surgery during recent 7 years in Yensei University College of Medicine, Severance Hospital. The characteristic radiological picture of each disease was discussed for precise radiologic diagnosis. 1. Of total 66 cases, there were 52 cases of benign gastric tumor 10 cases of gastric varices, 5 cases of gastric bezoar, 5 cases of corrosive gastritis, 3 cases of granulomatous disease and one case of gastric hematoma. 2. The most frequent causes of benign tumors were adenomatous polyp (35/42) and the next was leiomyoma (4/42). Others were one of case of carcinoid, neurofibroma and cyst. 3. Characteristic of benign adenomatous polyp were relatively small in size, smooth surface and were observed that large size, benign polyp was frequently type IV lesion with a stalk. 4. Submucosal tumors such as leiomyoma needed differential diagnosis with polypoid malignant cancer. However, the characteristic points of differentiation was well circumscribed smooth margined filling defect without definite mucosal destruction on surface. 5. Gastric varices showed multiple lobulated filling defected especially on gastric fundus that changed its size and shape by respiration and posture of patients. Same varices lesions on esophagus and history of liver disease were helpful for easier diagnosis. 6. Gastric bezoar showed well defined movable mass

  14. Benign gastric filling defect

    International Nuclear Information System (INIS)

    Oh, K. K.; Lee, Y. H.; Cho, O. K.; Park, C. Y.

    1979-01-01

    The gastric lesion is a common source of complaints to Orientals, however, evaluation of gastric symptoms and laboratory examination offer little specific aid in the diagnosis of gastric diseases. Thus roentgenography of gastrointestinal tract is one of the most reliable method for detail diagnosis. On double contract study of stomach, gastric filling defect is mostly caused by malignant gastric cancer, however, other benign lesions can cause similar pictures which can be successfully treated by surgery. 66 cases of benign causes of gastric filling defect were analyzed at this point of view, which was verified pathologically by endoscope or surgery during recent 7 years in Yensei University College of Medicine, Severance Hospital. The characteristic radiological picture of each disease was discussed for precise radiologic diagnosis. 1. Of total 66 cases, there were 52 cases of benign gastric tumor 10 cases of gastric varices, 5 cases of gastric bezoar, 5 cases of corrosive gastritis, 3 cases of granulomatous disease and one case of gastric hematoma. 2. The most frequent causes of benign tumors were adenomatous polyp (35/42) and the next was leiomyoma (4/42). Others were one of case of carcinoid, neurofibroma and cyst. 3. Characteristic of benign adenomatous polyp were relatively small in size, smooth surface and were observed that large size, benign polyp was frequently type IV lesion with a stalk. 4. Submucosal tumors such as leiomyoma needed differential diagnosis with polypoid malignant cancer. However, the characteristic points of differentiation was well circumscribed smooth margined filling defect without definite mucosal destruction on surface. 5. Gastric varices showed multiple lobulated filling defected especially on gastric fundus that changed its size and shape by respiration and posture of patients. Same varices lesions on esophagus and history of liver disease were helpful for easier diagnosis. 6. Gastric bezoar showed well defined movable mass

  15. Energetics of defects on graphene through fluorination.

    Science.gov (United States)

    Xiao, Jie; Meduri, Praveen; Chen, Honghao; Wang, Zhiguo; Gao, Fei; Hu, Jianzhi; Feng, Ju; Hu, Mary; Dai, Sheng; Brown, Suree; Adcock, Jamie L; Deng, Zhiqun; Liu, Jun; Graff, Gordon L; Aksay, Ilhan A; Zhang, Ji-Guang

    2014-05-01

    Functionalized graphene sheets (FGSs) comprise a unique member of the carbon family, demonstrating excellent electrical conductivity and mechanical strength. However, the detailed chemical composition of this material is still unclear. Herein, we take advantage of the fluorination process to semiquantitatively probe the defects and functional groups on graphene surface. Functionalized graphene sheets are used as substrate for low-temperature (DFT) and quantified experimentally by nuclear magnetic resonance (NMR). The electrochemical properties of fluorinated graphene are also discussed extending the use of graphene from fundamental research to practical applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Dual-probe spectroscopic fingerprints of defects in graphene

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Power, Stephen; Petersen, Dirch Hjorth

    2014-01-01

    (e.g., an extended graphene sheet). Applying this method, we study the transport anisotropies in pristine graphene sheets, and analyze the spectroscopic fingerprints arising from quantum interference around single-site defects, such as vacancies and adatoms. Furthermore, we demonstrate that the dual...

  17. Surface defect indices and 2d-4d BPS states

    Science.gov (United States)

    Córdova, Clay; Gaiotto, Davide; Shao, Shu-Heng

    2017-12-01

    We conjecture a formula for the Schur index of four-dimensional N=2 theories coupled to (2, 2) surface defects in terms of the 2 d-4 d BPS spectrum in the Coulomb phase of the theory. The key ingredient in our conjecture is a refined 2 d-4 d wall-crossing invariant, which we also formulate. Our result intertwines recent conjectures expressing the four-dimensional Schur index in terms of infrared BPS particles, with the Cecotti-Vafa formula for limits of the elliptic genus in terms of two-dimensional BPS solitons. We extend our discussion to framed 2 d-4 d BPS states, and use this to demonstrate a general relationship between surface defect indices and line defect indices. We illustrate our results in the example of su(2) super Yang-Mills coupled to the ℂℙ1 sigma model defect.

  18. Effect of charged line defects on conductivity in graphene: Numerical Kubo and analytical Boltzmann approaches

    DEFF Research Database (Denmark)

    Radchenko, T. M.; Shylau, A. A.; Zozoulenko, I. V.

    2013-01-01

    Charge carrier transport in single-layer graphene with one-dimensional charged defects is studied theoretically. Extended charged defects, considered an important factor for mobility degradation in chemically vapor-deposited graphene, are described by a self-consistent Thomas-Fermi potential...

  19. Extended Irreversible Thermodynamics

    CERN Document Server

    Jou, David

    2010-01-01

    This is the 4th edition of the highly acclaimed monograph on Extended Irreversible Thermodynamics, a theory that goes beyond the classical theory of irreversible processes. In contrast to the classical approach, the basic variables describing the system are complemented by non-equilibrium quantities. The claims made for extended thermodynamics are confirmed by the kinetic theory of gases and statistical mechanics. The book covers a wide spectrum of applications, and also contains a thorough discussion of the foundations and the scope of the current theories on non-equilibrium thermodynamics. For this new edition, the authors critically revised existing material while taking into account the most recent developments in fast moving fields such as heat transport in micro- and nanosystems or fast solidification fronts in materials sciences. Several fundamental chapters have been revisited emphasizing physics and applications over mathematical derivations. Also, fundamental questions on the definition of non-equil...

  20. Point defects in nickel

    International Nuclear Information System (INIS)

    Peretto, P.

    1969-01-01

    The defects in electron irradiated nickel (20 deg. K) or neutron irradiated nickel (28 deg. K) are studied by simultaneous analysis using the magnetic after-effect, electron microscopy and electrical resistivity recovery. We use zone refined nickel (99.999 per cent) which, for some experiments, is alloyed with a small amount of iron (for example 0.1 per cent Fe). The temperature dependant electrical recovery may be divided in four stages. The sub-stages I B (31 deg. K), I C (42 deg. K), I D (from to 57 deg. K) and I E (62 deg. K) of stage I are due to the disappearance of single interstitials into vacancies. The interstitial defect has a split configuration with a migration energy of about 0.15 eV. In the close pair which disappears in stage I B the interstitial is found to be in a 3. neighbour position whilst in stage I D it is near the direction from the vacancy. In stage I E there is no longer any interaction between the interstitial and the vacancy. The stage II is due to more complicated interstitial defects: di-interstitials for stage II B (84 deg. K) and larger and larger interstitial loops for the following sub-stages. The loops may be seen by electron microscopy. Impurities can play the role of nucleation centers for the loops. Stages III A (370 deg. K) and III B (376 deg. K) are due to two types of di-vacancies. During stage IV (410 deg. K) the single vacancies migrate. Vacancy type loops and interstitial type loops grow concurrently and disappear at about 800 deg. K as observed by electron microscopy. (author) [fr

  1. The dialogically extended mind

    DEFF Research Database (Denmark)

    Fusaroli, Riccardo; Gangopadhyay, Nivedita; Tylén, Kristian

    2014-01-01

    , we argue that language enhances our cognitive capabilities in a much more radical way: The skilful engagement of public material symbols facilitates evolutionarily unprecedented modes of collective perception, action and reasoning (interpersonal synergies) creating dialogically extended minds. We...... relate our approach to other ideas about collective minds and review a number of empirical studies to identify the mechanisms enabling the constitution of interpersonal cognitive systems....

  2. Extended quantum mechanics

    International Nuclear Information System (INIS)

    Pavel Bona

    2000-01-01

    The work can be considered as an essay on mathematical and conceptual structure of nonrelativistic quantum mechanics which is related here to some other (more general, but also to more special and 'approximative') theories. Quantum mechanics is here primarily reformulated in an equivalent form of a Poisson system on the phase space consisting of density matrices, where the 'observables', as well as 'symmetry generators' are represented by a specific type of real valued (densely defined) functions, namely the usual quantum expectations of corresponding selfjoint operators. It is shown in this paper that inclusion of additional ('nonlinear') symmetry generators (i. e. 'Hamiltonians') into this reformulation of (linear) quantum mechanics leads to a considerable extension of the theory: two kinds of quantum 'mixed states' should be distinguished, and operator - valued functions of density matrices should be used in the role of 'nonlinear observables'. A general framework for physical theories is obtained in this way: By different choices of the sets of 'nonlinear observables' we obtain, as special cases, e.g. classical mechanics on homogeneous spaces of kinematical symmetry groups, standard (linear) quantum mechanics, or nonlinear extensions of quantum mechanics; also various 'quasiclassical approximations' to quantum mechanics are all sub theories of the presented extension of quantum mechanics - a version of the extended quantum mechanics. A general interpretation scheme of extended quantum mechanics extending the usual statistical interpretation of quantum mechanics is also proposed. Eventually, extended quantum mechanics is shown to be (included into) a C * -algebraic (hence linear) quantum theory. Mathematical formulation of these theories is presented. The presentation includes an analysis of problems connected with differentiation on infinite-dimensional manifolds, as well as a solution of some problems connected with the work with only densely defined unbounded

  3. Electrical Characterisation of electron beam exposure induced Defects in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Danga, Helga T., E-mail: helga.danga@up.ac.za; Auret, Francois D.; Coelho, Sergio M.M.; Diale, Mmantsae

    2016-01-01

    The defects introduced in epitaxially grown p-type silicon (Si) during electron beam exposure were electrically characterised using deep level transient spectroscopy (DLTS) and high resolution Laplace-DLTS. In this process, Si samples were first exposed to the conditions of electron beam deposition (EBD) without metal deposition. This is called electron beam exposure (EBE) herein. After 50 minutes of EBE, nickel (Ni) Schottky contacts were fabricated using the resistive deposition method. The defect level observed using the Ni contacts had an activation energy of H(0.55). This defect has an activation energy similar to that of the I-defect. The defect level is similar to that of the HB4, a boron related defect. DLTS depth profiling revealed that H(0.55) could be detected up to a depth of 0.8 μm below the junction. We found that exposing the samples to EBD conditions without metal deposition introduced a defect which was not introduced by the EBD method. We also observed that the damage caused by EBE extended deeper into the material compared to that caused by EBD.

  4. Single ventricle cardiac defect

    International Nuclear Information System (INIS)

    Eren, B.; Turkmen, N.; Fedakar, R.; Cetin, V.

    2010-01-01

    Single ventricle heart is defined as a rare cardiac abnormality with a single ventricle chamber involving diverse functional and physiological defects. Our case is of a ten month-old baby boy who died shortly after admission to the hospital due to vomiting and diarrhoea. Autopsy findings revealed cyanosis of finger nails and ears. Internal examination revealed; large heart, weighing 60 grams, single ventricle, without a septum and upper membranous part. Single ventricle is a rare pathology, hence, this paper aims to discuss this case from a medico-legal point of view. (author)

  5. Dipole defects in beryl

    International Nuclear Information System (INIS)

    Holanda, B A; Cordeiro, R C; Blak, A R

    2010-01-01

    Dipole defects in gamma irradiated and thermally treated beryl (Be 3 Al 2 Si 6 O 18 ) samples have been studied using the Thermally Stimulated Depolarization Currents (TSDC) technique. TSDC experiments were performed in pink (morganite), green (emerald), blue (aquamarine) and colourless (goshenite) natural beryl. TSDC spectra present dipole peaks at 190K, 220K, 280K and 310K that change after gamma irradiation and thermal treatments. In morganite samples, for thermal treatments between 700K and 1100K, the 280K peak increase in intensity and the band at 220K disappears. An increase of the 280K peak and a decrease of the 190K peak were observed in the TSDC spectra of morganite after a gamma irradiation of 25kGy performed after the thermal treatments. In the case of emerald samples, thermal treatments enhanced the 280K peak and gamma irradiation partially destroyed this band. The goshenite TSDC spectra present only one band at 280K that is not affected either by thermal treatments or by gamma irradiation. All the observed peaks are of dipolar origin because the intensity of the bands is linearly dependent on the polarization field, behaviour of dipole defects. The systematic study, by means of TSDC measurements, of ionizing irradiation effects and thermal treatments in these crystals makes possible a better understanding of the role played by the impurities in beryl crystals.

  6. Enhancing native defect sensitivity for EUV actinic blank inspection: optimized pupil engineering and photon noise study

    Science.gov (United States)

    Wang, Yow-Gwo; Neureuther, Andrew; Naulleau, Patrick

    2016-03-01

    In this paper, we discuss the impact of optimized pupil engineering and photon noise on native defect sensitivity in EUV actinic blank inspection. Native defects include phase-dominated defects, absorber defects, and defects with a combination of phase and absorption behavior. First, we extend the idea of the Zernike phase contrast (ZPC) method and study the impact of optimum phase shift in the pupil plane on native defect sensitivity, showing a 23% signal-to-noise ratio (SNR) enhancement compare to bright field (BF) for a phase defect with 20% absorption. We also describe the possibility to increase target defect SNR on target defect sizes at the price of losing the sensitivity on smaller (non-critical) defects. Moreover, we show the advantage of the optimized phase contrast (OZPC) method over BF EUV actinic blank inspection. A single focus scan from OZPC has better inspection efficiency over BF. Second, we make a detailed comparison between the phase contrast with apodization (AZPC) method and dark field (DF) method based on defect sensitivity in the presence of both photon shot noise and camera noise. Performance is compared for a variety of photon levels, mask roughness conditions, and combinations of defect phase and absorption.

  7. Extended Testability Analysis Tool

    Science.gov (United States)

    Melcher, Kevin; Maul, William A.; Fulton, Christopher

    2012-01-01

    The Extended Testability Analysis (ETA) Tool is a software application that supports fault management (FM) by performing testability analyses on the fault propagation model of a given system. Fault management includes the prevention of faults through robust design margins and quality assurance methods, or the mitigation of system failures. Fault management requires an understanding of the system design and operation, potential failure mechanisms within the system, and the propagation of those potential failures through the system. The purpose of the ETA Tool software is to process the testability analysis results from a commercial software program called TEAMS Designer in order to provide a detailed set of diagnostic assessment reports. The ETA Tool is a command-line process with several user-selectable report output options. The ETA Tool also extends the COTS testability analysis and enables variation studies with sensor sensitivity impacts on system diagnostics and component isolation using a single testability output. The ETA Tool can also provide extended analyses from a single set of testability output files. The following analysis reports are available to the user: (1) the Detectability Report provides a breakdown of how each tested failure mode was detected, (2) the Test Utilization Report identifies all the failure modes that each test detects, (3) the Failure Mode Isolation Report demonstrates the system s ability to discriminate between failure modes, (4) the Component Isolation Report demonstrates the system s ability to discriminate between failure modes relative to the components containing the failure modes, (5) the Sensor Sensor Sensitivity Analysis Report shows the diagnostic impact due to loss of sensor information, and (6) the Effect Mapping Report identifies failure modes that result in specified system-level effects.

  8. Classical extended superconformal symmetries

    International Nuclear Information System (INIS)

    Viswanathan, R.R.

    1990-10-01

    Super-covariant differential operators are defined in two dimensions which map supersymmetry doublets to other doublets. The possibility of constructing a closed algebra among the fields appearing in such operators is explored. Such an algebra exists for Grassmann-odd differential operators. A representation for these operators in terms of free-field doublets is constructed. An explicit closed algebra involving fields of spin 2 and 5/2, in addition to the stress tensor and the supersymmetry generator, is constructed from such a free-field representation as an example of a non-linear extended superconformal algebra. (author). 9 refs

  9. Diaphragmatic defect in trisomy 13

    International Nuclear Information System (INIS)

    Reinbold, W.D.; Reinwein, H.; Back, E.

    1986-01-01

    Congenital diaphragmatic defect is often combined with other malformations that are severe or fatal. The rare finding of a congenital diaphragmatic defect in a newborn with trisomy 13 is reported. The newborn died within 2 days. Postmortem examination showed typical malformations due to trisomy 13 besides a diaphragmatic defect of left retrosternal position. Karyotype revealed a 13/14 translocation of trisomy 13. (orig.) [de

  10. Who named the quantum defect?

    Energy Technology Data Exchange (ETDEWEB)

    Rau, A.R.P. [Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Physics and Astronomy; Inokuti, M. [Argonne National Lab., IL (United States). Physics Div.

    1997-08-01

    The notion of the quantum defect is important in atomic and molecular spectroscopy and also in unifying spectroscopy with collision theory. In the latter context, the quantum defect may be viewed as an ancestor of the phase shift. However, the origin of the term quantum defect does not seem to be explained in standard textbooks. It occurred in a 1921 paper by Schroedinger, preceding quantum mechanics, yet giving the correct meaning as an index of the short-range interactions with the core of an atom. The authors present the early history of the quantum-defect idea, and sketch its recent developments.

  11. Studies of defects and defect agglomerates by positron annihilation spectroscopy

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard; Singh, B.N.

    1997-01-01

    A brief introduction to positron annihilation spectroscopy (PAS), and in particular lo its use for defect studies in metals is given. Positrons injected into a metal may become trapped in defects such as vacancies, vacancy clusters, voids, bubbles and dislocations and subsequently annihilate from...

  12. 2012 Gordon Research Conference on Defects in Semiconductors - Formal Schedule and Speaker/Poster Program

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, Evan [Naval Research Lab. (NRL), Washington, DC (United States)

    2012-08-17

    The meeting shall strive to develop and further the fundamental understanding of defects and their roles in the structural, electronic, optical, and magnetic properties of bulk, thin film, and nanoscale semiconductors and device structures. Point and extended defects will be addressed in a broad range of electronic materials of particular current interest, including wide bandgap semiconductors, metal-oxides, carbon-based semiconductors (e.g., diamond, graphene, etc.), organic semiconductors, photovoltaic/solar cell materials, and others of similar interest. This interest includes novel defect detection/imaging techniques and advanced defect computational methods.

  13. Lunar Prospector Extended Mission

    Science.gov (United States)

    Folta, David; Beckman, Mark; Lozier, David; Galal, Ken

    1999-01-01

    The National Aeronautics and Space Administration (NASA) selected Lunar Prospector (LP) as one of the discovery missions to conduct solar system exploration science investigations. The mission is NASA's first lunar voyage to investigate key science objectives since Apollo and was launched in January 1998. In keeping with discovery program requirements to reduce total mission cost and utilize new technology, Lunar Prospector's mission design and control focused on the use of innovative and proven trajectory analysis programs. As part of this effort, the Ames Research Center and the Goddard Space Flight Center have become partners in the Lunar Prospector trajectory team to provide the trajectory analysis, maneuver planning, orbit determination support, and product generation. At the end of 1998, Lunar Prospector completed its one-year primary mission at 100 km altitude above the lunar surface. On December 19, 1998, Lunar Prospector entered the extended mission phase. Initially the mission orbit was lowered from 100 km to a mean altitude of 40 km. The altitude of Lunar Prospector varied between 25 and 55 km above the mean lunar geode due to lunar potential effects. After one month, the lunar potential model was updated based upon the new tracking data at 40 km. On January 29, 1999, the altitude was lowered again to a mean altitude of 30 km. This altitude varies between 12 and 48 km above the mean lunar geode. Since the minimum altitude is very close to the mean geode, various approaches were employed to get accurate lunar surface elevation including Clementine altimetry and line of sight analysis. Based upon the best available terrain maps, Lunar Prospector will reach altitudes of 8 km above lunar mountains in the southern polar and far side regions. This extended mission phase of six months will enable LP to obtain science data up to 3 orders of magnitude better than at the mission orbit. This paper details the trajectory design and orbit determination planning and

  14. Birth defects surveillance in China.

    Science.gov (United States)

    Dai, Li; Zhu, Jun; Liang, Juan; Wang, Yan-Ping; Wang, He; Mao, Meng

    2011-11-01

    Birth defects are a global public health problem because of their large contribution to infant mortalities and disabilities. It is estimated that 4%-6% of Chinese newborns are affected by birth defects every year. Surveillance is a basic approach to understanding the occurrence and associated factors of birth defects. The Ministry of Health of China initiated a national hospital-based birth defects monitoring system 20 years ago. Nearly every province in this country has established its own surveillance system in the past. The authors reviewed the result of the monitoring system at different administrative levels in China. Available publications on the surveillance of birth defects and data from national and provincial birth defects surveillance systems were reviewed to evaluate the effectiveness of the surveillance systems. According to the 2009 data, the national hospital-based birth defects surveillance system monitored over 1.3 million births, which accounted for more than 8% of births in China. In addition, 30 provincial hospital-based surveillance programs covered a birth population of more than 3.6 million (22% of births in China). Great achievements have been made in terms of case ascertainment, data quality control, and online reporting. But the surveillance systems in China still have some limitations. A short ascertainment period may miss some internal anomalies, inherited metabolic diseases, and malformed fetus aborted before the 28th gestational week. Discrepancies in antenatal or postnatal diagnosis of birth defects between surveillance institutes may affect the detection rate and introduce biases. Absence of baseline data and lack of integrated database systems limit the application of surveillance data to etiological studies and affect the process of decision-making. The surveillance system for birth defects is prerequisite to propose, conduct and assess any interventions for the disease. To meet the need of study and prevention of birth defects

  15. Extended biorthogonal matrix polynomials

    Directory of Open Access Journals (Sweden)

    Ayman Shehata

    2017-01-01

    Full Text Available The pair of biorthogonal matrix polynomials for commutative matrices were first introduced by Varma and Tasdelen in [22]. The main aim of this paper is to extend the properties of the pair of biorthogonal matrix polynomials of Varma and Tasdelen and certain generating matrix functions, finite series, some matrix recurrence relations, several important properties of matrix differential recurrence relations, biorthogonality relations and matrix differential equation for the pair of biorthogonal matrix polynomials J(A,B n (x, k and K(A,B n (x, k are discussed. For the matrix polynomials J(A,B n (x, k, various families of bilinear and bilateral generating matrix functions are constructed in the sequel.

  16. Extending rational maps

    Science.gov (United States)

    Martin, Gaven J.

    We investigate when a rational endomorphism of the Riemann sphere overline{C} extends to a mapping of the upper half-space {H3 which is rational with respect to some measurable conformal structure. Such an extension has the property that it and all its iterates have uniformly bounded distortion. Such maps are called uniformly quasiregular. We show that, in the space of rational mappings of degree d , such an extension is possible in the structurally stable component where there is a single (attracting) component of the Fatou set and the Julia set is a Cantor set. We show that generally outside of this set no such extension is possible. In particular, polynomials can never admit such an extension.

  17. Extending juvenility in grasses

    Energy Technology Data Exchange (ETDEWEB)

    Kaeppler, Shawn; de Leon Gatti, Natalia; Foerster, Jillian

    2017-04-11

    The present invention relates to compositions and methods for modulating the juvenile to adult developmental growth transition in plants, such as grasses (e.g. maize). In particular, the invention provides methods for enhancing agronomic properties in plants by modulating expression of GRMZM2G362718, GRMZM2G096016, or homologs thereof. Modulation of expression of one or more additional genes which affect juvenile to adult developmental growth transition such as Glossy15 or Cg1, in conjunction with such modulation of expression is also contemplated. Nucleic acid constructs for down-regulation of GRMZM2G362718 and/or GRMZM2G096016 are also contemplated, as are transgenic plants and products produced there from, that demonstrate altered, such as extended juvenile growth, and display associated phenotypes such as enhanced yield, improved digestibility, and increased disease resistance. Plants described herein may be used, for example, as improved forage or feed crops or in biofuel production.

  18. Extended Poisson Exponential Distribution

    Directory of Open Access Journals (Sweden)

    Anum Fatima

    2015-09-01

    Full Text Available A new mixture of Modified Exponential (ME and Poisson distribution has been introduced in this paper. Taking the Maximum of Modified Exponential random variable when the sample size follows a zero truncated Poisson distribution we have derived the new distribution, named as Extended Poisson Exponential distribution. This distribution possesses increasing and decreasing failure rates. The Poisson-Exponential, Modified Exponential and Exponential distributions are special cases of this distribution. We have also investigated some mathematical properties of the distribution along with Information entropies and Order statistics of the distribution. The estimation of parameters has been obtained using the Maximum Likelihood Estimation procedure. Finally we have illustrated a real data application of our distribution.

  19. Extending over time

    DEFF Research Database (Denmark)

    Christensen, Tanya Karoli; Jensen, Torben Juel; Christensen, Marie Herget

    Studies of general extenders (GEs), such as Eng. and stuff like that, or something, typically find that it is a feature of youth speech, sometimes correlated with sex and class (e.g. Dubois 1992, Stubbe and Holmes 1995, Cheshire 2007, Tagliamonte and Denis 2010, Pichler and Levey 2011), but only...... including pronoun headed phrases, e.g. og (alt) det der ‘and (all) that there’, and clausal variants, e.g. og jeg ved ikke hvad ‘and I don’t know what’. The results indicate that Danish GEs in general are already gram-maticalized to a large extent. Regarding social factors, our data support the general...... finding that GEs are more frequent in youth speech. Adolescents have the highest relative frequency of GEs, and speakers tend to decrease their GE use during their life span, whilst participating in community changes regarding the use of the different GE types. Furthermore, the results suggest...

  20. Ocular Defects in Photosensitive Epilepsy

    Directory of Open Access Journals (Sweden)

    Ebere C. Anyanwu

    2004-01-01

    Full Text Available Patients with photosensitive epilepsy are susceptible to seizures due to photoparoxysmal response (PPR. This response adversely precipitates factors that modify the functional status of the visual system. Such factors may or may not be evident superficially, but may lead to ocular defects due to trauma, hormonal imbalance, abnormal intraocular pressure (IOP, or any other reflex-inducing stimuli. The extent to which photosensitive epileptic patients suffer from PPR-related ocular defects has not been documented fully. In this investigation, ocular defects in patients with photosensitive epilepsy are studied using visual-evoked response (VER. A total of 212 photosensitive epileptic patients were studied to ascertain the magnitude and distribution of ocular defects using the changes in EEG and visual-evoked potential (VEP; 51% of the patients were female, the age range was 1–46 years. The major ocular defects and complications found were visual field defects, optic nerve abnormalities, nystagmus, cataracts, amblyopia, and migraine. These findings were analyzed according to age and sex. The relationship between the ocular abnormalities and the interpretations of the changes in the characteristics of the VEP indicated that optic-related atrophies, visual defects, optic neuritis, chiasmal compression, nystagmus, migraine headache, cataracts, and amblyopia were prevalent in photosensitive epileptic patients at varying degrees. The results showed that although ocular defects in photosensitive epilepsy may not be obvious differentially, VEP can be used in their diagnosis, contrary to earlier studies reporting that VEP is not of much value in epilepsy diagnosis.

  1. Space mapping and defect correction

    NARCIS (Netherlands)

    Echeverría, D.; Hemker, P.W.

    2005-01-01

    In this paper we show that space-mapping optimization can be understood in the framework of defect correction. Then, space-mapping algorithms can be seen as special cases of defect correction iteration. In order to analyze the properties of space mapping and the space-mapping function, we introduce

  2. Birth defects surveillance·

    African Journals Online (AJOL)

    1989-07-01

    Jul 1, 1989 ... A pilot birth defects surveillance system was established in. 1982 as part of an epidemiological baseline study pertaining to potential changes in water quality in the Cape Peninsula. The methodology used for reporting birth defects for two information systems, one hospital-based and the other popu-.

  3. A review of defects and disorder in multinary tetrahedrally bonded semiconductors

    Science.gov (United States)

    Baranowski, Lauryn L.; Zawadzki, Pawel; Lany, Stephan; Toberer, Eric S.; Zakutayev, Andriy

    2016-12-01

    Defects are critical to understanding the electronic properties of semiconducting compounds, for applications such as light-emitting diodes, transistors, photovoltaics, and thermoelectrics. In this review, we describe our work investigating defects in tetrahedrally bonded, multinary semiconductors, and discuss the place of our research within the context of publications by other groups. We applied experimental and theory techniques to understand point defects, structural disorder, and extended antisite defects in one semiconductor of interest for photovoltaic applications, Cu2SnS3. We contrast our findings on Cu2SnS3 with other chemically related Cu-Sn-S compounds, as well as structurally related compounds such as Cu2ZnSnS4 and Cu(In,Ga)Se2. We find that evaluation of point defects alone is not sufficient to understand defect behavior in multinary tetrahedrally bonded semiconductors. In the case of Cu2SnS3 and Cu2ZnSnS4, structural disorder and entropy-driven cation clustering can result in nanoscale compositional inhomogeneities which detrimentally impact the electronic transport. Therefore, it is not sufficient to assess only the point defect behavior of new multinary tetrahedrally bonded compounds; effects such as structural disorder and extended antisite defects must also be considered. Overall, this review provides a framework for evaluating tetrahedrally bonded semiconducting compounds with respect to their defect behavior for photovoltaic and other applications, and suggests new materials that may not be as prone to such imperfections.

  4. Holographic Chern-Simons defects

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, Mitsutoshi [Department of Physics and Astronomy, University of Kentucky,Lexington, KY 40506 (United States); Yukawa Institute for Theoretical Physics, Kyoto University,Kyoto 606-8502 (Japan); Melby-Thompson, Charles M. [Department of Physics, Fudan University,220 Handan Road, 200433 Shanghai (China); Kavli Institute for the Physics and Mathematics of the Universe (WPI),The University of Tokyo Institutes for Advanced Study (UTIAS),The University of Tokyo, Kashiwanoha, Kashiwa, 277-8583 (Japan); Meyer, René [Department of Physics and Astronomy, Stony Brook University,Stony Brook, New York 11794-3800 (United States); Kavli Institute for the Physics and Mathematics of the Universe (WPI),The University of Tokyo Institutes for Advanced Study (UTIAS),The University of Tokyo, Kashiwanoha, Kashiwa, 277-8583 (Japan); Sugimoto, Shigeki [Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University,Kyoto 606-8502 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (WPI),The University of Tokyo Institutes for Advanced Study (UTIAS),The University of Tokyo, Kashiwanoha, Kashiwa, 277-8583 (Japan)

    2016-06-28

    We study SU(N) Yang-Mills-Chern-Simons theory in the presence of defects that shift the Chern-Simons level from a holographic point of view by embedding the system in string theory. The model is a D3-D7 system in Type IIB string theory, whose gravity dual is given by the AdS soliton background with probe D7 branes attaching to the AdS boundary along the defects. We holographically renormalize the free energy of the defect system with sources, from which we obtain the correlation functions for certain operators naturally associated to these defects. We find interesting phase transitions when the separation of the defects as well as the temperature are varied. We also discuss some implications for the Fractional Quantum Hall Effect and for 2-dimensional QCD.

  5. Toward Intelligent Software Defect Detection

    Science.gov (United States)

    Benson, Markland J.

    2011-01-01

    Source code level software defect detection has gone from state of the art to a software engineering best practice. Automated code analysis tools streamline many of the aspects of formal code inspections but have the drawback of being difficult to construct and either prone to false positives or severely limited in the set of defects that can be detected. Machine learning technology provides the promise of learning software defects by example, easing construction of detectors and broadening the range of defects that can be found. Pinpointing software defects with the same level of granularity as prominent source code analysis tools distinguishes this research from past efforts, which focused on analyzing software engineering metrics data with granularity limited to that of a particular function rather than a line of code.

  6. Defect forces, defect couples and path integrals in fracture mechanics

    International Nuclear Information System (INIS)

    Roche, R.L.

    1979-07-01

    In this work, it is shown that the path integrals can be introduced without any reference to the material behavior. The method is based on the definition in a continuous medium of a set of vectors and couples having the dimension of a force or a moment. More precisely, definitions are given of volume defect forces, surface defect forces, volume defect couples, and surface defect couples. This is done with the help of the stress working variation of a particule moving through the solid. The most important result is: the resultant of all the defect forces included in a volume V is the J integral on the surface surrounding V and the moment resultant is the L integral. So these integrals are defined without any assumption on the material constitutive equation. Another result is the material form of the virtual work principle - defect forces are acting like conventional forces in the conventional principles of virtual work. This lead to the introduction of the energy momentum tensor and of the associated couple stress. Application of this method is made to fracture mechanics in studying the defect forces distribution around a crack [fr

  7. Extended lactation in dairy cows

    DEFF Research Database (Denmark)

    Sorensen, Annette; Muir, D. Donald; Knight, Christopher Harold

    2008-01-01

    Twelve spring-calving and twelve winter-calving cows were managed for extended lactation cycles of 18-months duration, with the former group then completing a second extended lactation. Half of the cows were fed according to standard management practice for the herd; the other half received suppl...... interventions, the results lend support to the economic arguments in favour of extended lactation cycles. The likely welfare benefits of extended lactation are also discussed....

  8. Reconstruction of Defects After Fournier Gangrene: A Systematic Review.

    Science.gov (United States)

    Karian, Laurel S; Chung, Stella Y; Lee, Edward S

    2015-01-01

    Reconstruction of scrotal defects after Fournier gangrene is often achieved with skin grafts or flaps, but there is no general consensus on the best method of reconstruction or how to approach the exposed testicle. We systematically reviewed the literature addressing methods of reconstruction of Fournier defects after debridement. PubMed and Cochrane databases were searched from 1950 to 2013. Inclusion criteria were reconstruction for Fournier defects, patients 18 to 90 years old, and reconstructive complication rates reported as whole numbers or percentages. Exclusion criteria were studies focused on methods of debridement or other phases of care rather than reconstruction, studies with fewer than 5 male patients with Fournier defects, literature reviews, and articles not in English. The initial search yielded 982 studies, which was refined to 16 studies with a total pool of 425 patients. There were 25 (5.9%) patients with defects that healed by secondary intention, 44 (10.4%) with delayed primary closure, 36 (8.5%) with implantation of the testicle in a medial thigh pocket, 6 (1.4%) with loose wound approximation, 96 (22.6%) with skin grafts, 68 (16.0%) with scrotal advancement flaps, 128 (30.1%) with flaps, and 22 (5.2%) with flaps or skin grafts in combination with tissue adhesives. Four outcomes were evaluated: number of patients, defect size, method of reconstruction, and wound-healing complications. Most reconstructive techniques provide reliable coverage and protection of testicular function with an acceptable cosmetic result. There is no conclusive evidence to support flap coverage of exposed testes rather than skin graft. A reconstructive algorithm is proposed. Skin grafting or flap reconstruction is recommended for defects larger than 50% of the scrotum or extending beyond the scrotum, whereas scrotal advancement flap reconstruction or healing by secondary intention is best for defects confined to less than 50% of the scrotum that cannot be closed

  9. Automated Defect Classification (ADC) and Progression Monitoring (DPM) in wafer fab reticle requalification

    Science.gov (United States)

    Yen, T. H.; Lai, Rick; Tuo, Laurent C.; Tolani, Vikram; Chen, Dongxue; Hu, Peter; Yu, Jiao; Hwa, George; Zheng, Yan; Lakkapragada, Suresh; Wang, Kechang; Peng, Danping; Wang, Bill; Chiang, Kaiming

    2013-09-01

    As optical lithography continues to extend into low-k1 regime, resolution of mask patterns continue to diminish, and so do mask defect requirements due to increasing MEEF. Post-inspection, mask defects have traditionally been classified by operators manually based on visual review. This approach may have worked down to 65/55nm node layers. However, starting 45nm and smaller nodes, visually reviewing 50 to sometimes 100s of defects on masks with complex modelbased OPC, SRAF, and ILT geometries, is error-prone and takes up valuable inspection tool capacity. Both these shortcomings in manual defect review are overcome by adoption of the computational solution called Automated Defect Classification (ADC) wherein mask defects are accurately classified within seconds and consistent to guidelines used by production technicians and engineers.

  10. Entrainment of a spatially extended nonlinear structure under selective forcing.

    Science.gov (United States)

    Henriot, Michel; Burguete, Javier; Ribotta, Roland

    2003-09-05

    The response of a nonlinear state to a variable forcing periodic in space is studied in an extended dynamical system consisting of a liquid crystal layer driven to convection. Both the statics and the dynamics of the entrainment and the locking effects are analyzed. The dynamics of the evolution are controlled by topological singularities that allow a diffusion of the phase. The mechanisms involved are related to the role of the defects in systems undergoing spontaneous symmetry breakings.

  11. Serine biosynthesis and transport defects.

    Science.gov (United States)

    El-Hattab, Ayman W

    2016-07-01

    l-serine is a non-essential amino acid that is biosynthesized via the enzymes phosphoglycerate dehydrogenase (PGDH), phosphoserine aminotransferase (PSAT), and phosphoserine phosphatase (PSP). Besides its role in protein synthesis, l-serine is a potent neurotrophic factor and a precursor of a number of essential compounds including phosphatidylserine, sphingomyelin, glycine, and d-serine. Serine biosynthesis defects result from impairments of PGDH, PSAT, or PSP leading to systemic serine deficiency. Serine biosynthesis defects present in a broad phenotypic spectrum that includes, at the severe end, Neu-Laxova syndrome, a lethal multiple congenital anomaly disease, intermediately, infantile serine biosynthesis defects with severe neurological manifestations and growth deficiency, and at the mild end, the childhood disease with intellectual disability. A serine transport defect resulting from deficiency of the ASCT1, the main transporter for serine in the central nervous system, has been recently described in children with neurological manifestations that overlap with those observed in serine biosynthesis defects. l-serine therapy may be beneficial in preventing or ameliorating symptoms in serine biosynthesis and transport defects, if started before neurological damage occurs. Herein, we review serine metabolism and transport, the clinical, biochemical, and molecular aspects of serine biosynthesis and transport defects, the mechanisms of these diseases, and the potential role of serine therapy. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. DEFECTS SIMULATION OF ROLLING STRIP

    Directory of Open Access Journals (Sweden)

    Rudolf Mišičko

    2009-06-01

    Full Text Available The defects in the continuous casting slabs can be developed or kept down in principle by rolling technology, especially depend to sort, size and distribution of primary defects, as well as used of rolling parameters. Scope of the article is on observation behavior artificial surface and undersurface defects (scores without filler (surface defects and filling by oxides and casting powder (subsurface defects. First phase of hot rolling process have been done by software simulation DEFORM 3D setting to the limited condition for samples with surface defects. Samples of material with low-carbon steel of sizes h x b x l have been chosen and the surface defects shape „U” and „V” of scores have been injected artificially by software. The process of rolling have been simulated on the deformation temperatures 1200°C and 900°C, whereas on the both of this deformation temperatures have been applied amount of deformation 10 and 50 %. With respect to the process of computer simulation, it is not possible to truthful real oxidation condition (physical – chemical process during heat of metal, in the second phase of our investigation have been observed influence of oxides and casting powders inside the scores for a defect behavior in plastic deformation process (hot and cold rolling process in laboratory condition. The basic material was STN steel class 11 375, cladding material was steel on the bases C-Mn-Nb-V. Scores have been filled by scales to get from the heating temperatures (1100°C a 1250°C, varied types of casting powders, if you like mixture of scale and casting powders in the rate 1:4. The joint of the basic and cladding material have been done by peripheral welded joint. Experiment results from both phases are pointed on the evolution of original typology defects in rolling process.

  13. When Your Baby Has a Birth Defect

    Science.gov (United States)

    ... Search English Español When Your Baby Has a Birth Defect KidsHealth / For Parents / When Your Baby Has ... to help you and your child. What Are Birth Defects? Birth defects (also called congenital anomalies) are ...

  14. Defect detection based on extreme edge of defective region histogram

    Directory of Open Access Journals (Sweden)

    Zouhir Wakaf

    2018-01-01

    Full Text Available Automatic thresholding has been used by many applications in image processing and pattern recognition systems. Specific attention was given during inspection for quality control purposes in various industries like steel processing and textile manufacturing. Automatic thresholding problem has been addressed well by the commonly used Otsu method, which provides suitable results for thresholding images based on a histogram of bimodal distribution. However, the Otsu method fails when the histogram is unimodal or close to unimodal. Defects have different shapes and sizes, ranging from very small to large. The gray-level distributions of the image histogram can vary between unimodal and multimodal. Furthermore, Otsu-revised methods, like the valley-emphasis method and the background histogram mode extents, which overcome the drawbacks of the Otsu method, require preprocessing steps and fail to use the general threshold for multimodal defects. This study proposes a new automatic thresholding algorithm based on the acquisition of the defective region histogram and the selection of its extreme edge as the threshold value to segment all defective objects in the foreground from the image background. To evaluate the proposed defect-detection method, common standard images for experimentation were used. Experimental results of the proposed method show that the proposed method outperforms the current methods in terms of defect detection.

  15. Empirical formula for rates of hot pixel defects based on pixel size, sensor area, and ISO

    Science.gov (United States)

    Chapman, Glenn H.; Thomas, Rohit; Koren, Zahava; Koren, Israel

    2013-02-01

    Experimentally, image sensors measurements show a continuous development of in-field permanent hot pixel defects increasing in numbers over time. In our tests we accumulated data on defects in cameras ranging from large area (cell phone cameras. The results show that the rate of defects depends on the technology (APS or CCD), and on design parameters like imager area, pixel size (from 1.5 to 7 um), and gain (from ISO100 to 1600). Comparing different sensor sizes with similar pixel sizes has shown that defect rates scale linearly with sensor area, suggesting the metric of defects/year/sq mm, which we call defect density. A search was made to model this defect density as a function of the two parameters pixel size and ISO. The best empirical fit was obtained by a power law curve. For CCD imagers, the defect densities are proportional to the pixel size to the power of -2.25 times the ISO to the power of 0.69. For APS (CMOS) sensors the power law had the defect densities proportional to the pixel size to the power of -3.07 times the ISO raised to the power of 0.5. Extending our empirical formula to include ISO allows us to predict the expected defect development rate for a wide set of sensor parameters.

  16. Birth Defects Data and Statistics

    Science.gov (United States)

    ... Submit" /> Information For… Media Policy Makers Data & Statistics Recommend on Facebook Tweet Share Compartir On This ... and critical. Read below for the latest national statistics on the occurrence of birth defects in the ...

  17. What Are Congenital Heart Defects?

    Science.gov (United States)

    ... of a Normal Heart and a Heart With Tetralogy of Fallot Figure A shows the structure and blood flow ... shows a heart with the four defects of tetralogy of Fallot. Babies and children who have tetralogy of Fallot ...

  18. Birth Defects Research and Tracking

    Science.gov (United States)

    ... Environmental public health tracking is the ongoing collection, integration, analysis, interpretation, and dissemination of data on environmental ... 2016) Key Findings: Gastroschisis – a Serious Birth Defect – Continues to Increase New CDC research shows that the ...

  19. Defects in semiconductors

    International Nuclear Information System (INIS)

    Tilly, L.

    1993-04-01

    In this thesis, experimental results of the transition metals Ti, V, Nb, Mo, and W as impurity centres in silicon are presented. Transition metal doping was accomplished by ion implantation. Emphasis is put on energy level position, electrical and optical properties of the encountered defect levels. Junction space charge methods (JSCM) such as DLTS, photocapacitance and photocurrent techniques are employed. Three energy levels are found for the 3d-transition metals Ti(E c -0.06eV, E c -0.30eV, E v +0.26) and V(E c -0.21eV, E c -0,48e, E v +0.36eV), and for the 4d-element Nb(E c -0.29eV, E c -0.58eV, E v +0.163eV) in Silicon, whereas only one transition metal induced level is found for Mo(E v +0.30eV) and W(E v +0.38eV) respectively. Electrical and optical characteristics of Si 1-x Ge x ,0.7 7 cm -2 . The solvent Bi, used in the LPE-process, is found to be the dominant impurity element. Furthermore, liquid phase epitaxy of high purity In 0.53 Ga 0.57 As on InP, together with the properties of the Cu-induced acceptor in this material are examined. Free electron concentrations of n=5x10 14 cm -3 and electron Hall-mobilities of μ 77K = 44000 cm 2 /Vs are achieved. The energy level position of the Cu-acceptor is found to be E v +0.025eV. Photoluminescence and Hall-effect measurements, together with JSCM are the main characterization methods used. The band linups of In 0.53 Ga 0.47 As with GaAs and with InP are determined according to the Cu-acceptor energy level position in these materials. Additionally, the hydrostatic pressure dependence of the Cu-acceptor energy level position in In 0.53 Ga 0.47 As is examined. (103 refs.)

  20. Reconstruction of a midfacial defect using an intraoral-extraoral combination prosthesis employing magnets: a clinical report

    OpenAIRE

    Nair, Anoop; Regish, K M.; Shah, Farhan K.; Prithviraj, D R.

    2012-01-01

    Radical maxillectomy frequently leads to extended defects in hard and soft tissues that result in a connection between the oral cavities and orbit. If the defect cannot be surgically reconstructed, a combination prosthesis may be necessary to remedy dysfunction in patient function, comfort, esthetics. For minor defects, enlargement of the base of the intra oral prosthesis is generally sufficient. Resections that affect more than one third of the maxilla usually require an intra oral and an ex...

  1. Topological defects from the multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun; Vilenkin, Alexander [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Blanco-Pillado, Jose J. [Department of Theoretical Physics, University of the Basque Country UPV/EHU, 48080 Bilbao (Spain); Garriga, Jaume, E-mail: jun.zhang@tufts.edu, E-mail: josejuan.blanco@ehu.es, E-mail: jaume.garriga@ub.edu, E-mail: vilenkin@cosmos.phy.tufts.edu [Departament de Fisica Fonamental i Institut de Ciencies del Cosmos, Universitat de Barcelona, Marti i Franques, 1, 08028, Barcelona (Spain)

    2015-05-01

    Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to be quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly enhanced in the case where the cosmological constant of our parent vacuum is much higher than the vacuum energy density during inflation in our bubble.

  2. Topological defects from the multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Blanco-Pillado, Jose J. [Department of Theoretical Physics, University of the Basque Country UPV/EHU, 48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, 48013, Bilbao (Spain); Garriga, Jaume [Departament de Fisica Fonamental i Institut de Ciencies del Cosmos, Universitat de Barcelona, Marti i Franques, 1, 08028, Barcelona (Spain); Vilenkin, Alexander [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States)

    2015-05-28

    Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to be quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly enhanced in the case where the cosmological constant of our parent vacuum is much higher than the vacuum energy density during inflation in our bubble.

  3. Electrical fingerprint of pipeline defects

    International Nuclear Information System (INIS)

    Mica, Isabella; Polignano, Maria Luisa; Marco, Cinzia De

    2004-01-01

    Pipeline defects are dislocations that connect the source region of the transistor with the drain region. They were widely reported to occur in CMOS, BiCMOS devices and recently in SOI technologies. They can reduce device yield either by affecting the devices functionality or by increasing the current consumption under stand-by conditions. In this work the electrical fingerprint of these dislocations is studied, its purpose is to enable us to identify these defects as the ones responsible for device failure. It is shown that the pipeline defects are responsible for a leakage current from source to drain in the transistors. This leakage has a resistive characteristic and it is lightly modulated by the body bias. It is not sensitive to temperature; vice versa the off-current of a good transistor exhibits the well-known exponential dependence on 1/T. The emission spectrum of these defects was studied and compared with the spectrum of a good transistor. The paper aims to show that the spectrum of a defective transistor is quite peculiar; it shows well defined peaks, whereas the spectrum of a good transistor under saturation conditions is characterized by a broad spectral light emission distribution. Finally the deep-level transient spectroscopy (DLTS) is tried on defective diodes

  4. Effect of radiation-induced emission of Schottky defects on the formation of colloids in alkali halides

    NARCIS (Netherlands)

    Dubinko, [No Value; Vainshtein, DI; Den Hartog, HW

    2003-01-01

    Formation of vacancy clusters in irradiated crystals is considered taking into account radiation-induced Schottky defect emission (RSDE) from extended defects. RSDE acts in the opposite direction compared with Frenkel pair production, and it results in the radiation-induced recovery processes. In

  5. A DFT study of Cu nanoparticles adsorbed on defective graphene

    Energy Technology Data Exchange (ETDEWEB)

    García-Rodríguez, D.E. [Universidad Politécnica de Aguascalientes, Calle Paseo San Gerardo No. 297 Fracc. San Gerardo, 20342 Aguascalientes, Ags. (Mexico); Mendoza-Huizar, L.H. [Universidad Autónoma del Estado de Hidalgo, Área Académica de Química, Ciudad del Conocimiento. Carretera Pachuca-Tulancigo Km. 4.5 Mineral de la Reforma, 42186 Hidalgo (Mexico); Díaz, C., E-mail: cristina.diaz@uam.es [Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid (Spain); Institute for Advanced Research in Chemical Science (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid (Spain)

    2017-08-01

    Highlights: • Cu{sub n} supported on graphene may be a promising electrode material for DBFC's cells. • Cu{sub n}/graphene interaction is rather local and size independent. • Cu{sub 13} anchors strongly to defects in graphene, while keeping its gas-phase properties. - Abstract: Metal nanoparticles adsorbed on graphene are systems of interest for processes relative to catalytic reactions and alternative energy production. Graphene decorated with Cu-nanoparticles, in particular, could be a good alternative material for electrodes in direct borohydride fuel cells. However our knowledge of this system is still very limited. Based on density functional theory, we have analyzed the interaction of Cu{sub n} nanoparticles (n = 4, 5, 6, 7, 13) with pristine and defective-graphene. We have considered two types of defects, a single vacancy (SV), and an extended lineal structural defect (ELSD), formed by heptagon-pentagon pairs. Our analysis has revealed the covalent character of the Cu{sub n}-graphene interaction for pristine- and ELSD-graphene, and a more ionic-like interaction for SV-graphene. Furthermore, our analysis shows that the interaction between the nanoparticles and the graphene is rather local, i.e., only the nanoparticle atoms close to the contact region are involved in the interaction, being the electronic contact region much higher for defective-graphene than for pristine-graphene. Thus, the higher the particle the lower its average electronic and structural distortion.

  6. Analysis of Bending Waves in Phononic Crystal Beams with Defects

    Directory of Open Access Journals (Sweden)

    Yongqiang Guo

    2018-01-01

    Full Text Available Existing investigations on imperfect phononic crystal beams mainly concern periodic multi-span beams carrying either one or two channel waves with random or deterministic disorder in span-length. This paper studies the two channel bending waves in phononic crystal beams consisting of many phases of materials with defects introduced as one structural segment having different cross-sectional dimensions or material parameters. The method of reverberation-ray matrix (MRRM based on the Timoshenko beam theory, which can conduct high-frequency analysis, is extended for the theoretical analysis of dispersion and transmission of bending waves. The supercell technique and the Floquet–Bloch theorem are adopted for modeling the dispersion characteristics, and the whole finite structural model is used to calculate the transmission spectra. Experimental measurements and numerical calculations are provided to validate the displacement transmission obtained by the proposed MRRM, with the effect of damping on transmission spectra being concerned. The high-frequency calculation applicability of the proposed MRRM is also confirmed by comparing the present results with the corresponding ones either using the transfer matrix method (TMM or MRRM based on Euler—Bernoulli beam theory. The influences of defect size, defect form, and unit-cell number on the transmission spectra and the band structures are discussed. The drawn conclusions may be useful for designing or evaluating the defected phononic crystal beams in bending wave control. In addition, our conclusions are especially potential for identifying the defect location through bending wave signals.

  7. A DFT study of Cu nanoparticles adsorbed on defective graphene

    International Nuclear Information System (INIS)

    García-Rodríguez, D.E.; Mendoza-Huizar, L.H.; Díaz, C.

    2017-01-01

    Highlights: • Cu n supported on graphene may be a promising electrode material for DBFC's cells. • Cu n /graphene interaction is rather local and size independent. • Cu 13 anchors strongly to defects in graphene, while keeping its gas-phase properties. - Abstract: Metal nanoparticles adsorbed on graphene are systems of interest for processes relative to catalytic reactions and alternative energy production. Graphene decorated with Cu-nanoparticles, in particular, could be a good alternative material for electrodes in direct borohydride fuel cells. However our knowledge of this system is still very limited. Based on density functional theory, we have analyzed the interaction of Cu n nanoparticles (n = 4, 5, 6, 7, 13) with pristine and defective-graphene. We have considered two types of defects, a single vacancy (SV), and an extended lineal structural defect (ELSD), formed by heptagon-pentagon pairs. Our analysis has revealed the covalent character of the Cu n -graphene interaction for pristine- and ELSD-graphene, and a more ionic-like interaction for SV-graphene. Furthermore, our analysis shows that the interaction between the nanoparticles and the graphene is rather local, i.e., only the nanoparticle atoms close to the contact region are involved in the interaction, being the electronic contact region much higher for defective-graphene than for pristine-graphene. Thus, the higher the particle the lower its average electronic and structural distortion.

  8. Irreducibility conditions for extended superfields

    International Nuclear Information System (INIS)

    Sokatchev, E.

    1981-05-01

    The irreducible supermultiplets contained in an extended superfield are presented as sets of covariant derivatives of the superfield. Differential irreducibility constraints are easily obtained from this decomposition. (author)

  9. Influence of radiation induced defect clusters on silicon particle detectors

    Energy Technology Data Exchange (ETDEWEB)

    Junkes, Alexandra

    2011-10-15

    The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) addresses some of today's most fundamental questions of particle physics, like the existence of the Higgs boson and supersymmetry. Two large general-purpose experiments (ATLAS, CMS) are installed to detect the products of high energy protonproton and nucleon-nucleon collisions. Silicon detectors are largely employed in the innermost region, the tracking area of the experiments. The proven technology and large scale availability make them the favorite choice. Within the framework of the LHC upgrade to the high-luminosity LHC, the luminosity will be increased to L=10{sup 35} cm{sup -2}s{sup -1}. In particular the pixel sensors in the innermost layers of the silicon trackers will be exposed to an extremely intense radiation field of mainly hadronic particles with fluences of up to {phi}{sub eq}=10{sup 16} cm{sup -2}. The radiation induced bulk damage in silicon sensors will lead to a severe degradation of the performance during their operational time. This work focusses on the improvement of the radiation tolerance of silicon materials (Float Zone, Magnetic Czochralski, epitaxial silicon) based on the evaluation of radiation induced defects in the silicon lattice using the Deep Level Transient Spectroscopy and the Thermally Stimulated Current methods. It reveals the outstanding role of extended defects (clusters) on the degradation of sensor properties after hadron irradiation in contrast to previous works that treated effects as caused by point defects. It has been found that two cluster related defects are responsible for the main generation of leakage current, the E5 defects with a level in the band gap at E{sub C}-0.460 eV and E205a at E{sub C}-0.395 eV where E{sub C} is the energy of the edge of the conduction band. The E5 defect can be assigned to the tri-vacancy (V{sub 3}) defect. Furthermore, isochronal annealing experiments have shown that the V{sub 3} defect

  10. Influence of radiation induced defect clusters on silicon particle detectors

    International Nuclear Information System (INIS)

    Junkes, Alexandra

    2011-10-01

    The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) addresses some of today's most fundamental questions of particle physics, like the existence of the Higgs boson and supersymmetry. Two large general-purpose experiments (ATLAS, CMS) are installed to detect the products of high energy protonproton and nucleon-nucleon collisions. Silicon detectors are largely employed in the innermost region, the tracking area of the experiments. The proven technology and large scale availability make them the favorite choice. Within the framework of the LHC upgrade to the high-luminosity LHC, the luminosity will be increased to L=10 35 cm -2 s -1 . In particular the pixel sensors in the innermost layers of the silicon trackers will be exposed to an extremely intense radiation field of mainly hadronic particles with fluences of up to Φ eq =10 16 cm -2 . The radiation induced bulk damage in silicon sensors will lead to a severe degradation of the performance during their operational time. This work focusses on the improvement of the radiation tolerance of silicon materials (Float Zone, Magnetic Czochralski, epitaxial silicon) based on the evaluation of radiation induced defects in the silicon lattice using the Deep Level Transient Spectroscopy and the Thermally Stimulated Current methods. It reveals the outstanding role of extended defects (clusters) on the degradation of sensor properties after hadron irradiation in contrast to previous works that treated effects as caused by point defects. It has been found that two cluster related defects are responsible for the main generation of leakage current, the E5 defects with a level in the band gap at E C -0.460 eV and E205a at E C -0.395 eV where E C is the energy of the edge of the conduction band. The E5 defect can be assigned to the tri-vacancy (V 3 ) defect. Furthermore, isochronal annealing experiments have shown that the V 3 defect exhibits a bistability, as does the leakage current. In oxygen

  11. On core stability and extendability

    OpenAIRE

    Shellshear, Evan

    2007-01-01

    This paper investigates conditions under which the core of a TU cooperative game is stable. In particular the author extends the idea of extendability to find new conditions under which the core is stable. It is also shown that these new conditions are not necessary for core stability.

  12. Extending cosmology: the metric approach

    OpenAIRE

    Mendoza, S.

    2012-01-01

    Comment: 2012, Extending Cosmology: The Metric Approach, Open Questions in Cosmology; Review article for an Intech "Open questions in cosmology" book chapter (19 pages, 3 figures). Available from: http://www.intechopen.com/books/open-questions-in-cosmology/extending-cosmology-the-metric-approach

  13. Stoichiometric Defects in Silicon Carbide

    International Nuclear Information System (INIS)

    Liao, Ting; Bedoya-Martinez, O. N.; Roma, G.; Liao, Ting; Liao, Ting

    2010-01-01

    Defect structures showing odd-membered rings are known features of several tetrahedral semiconductors as well as carbon nano-structures; examples of them are bond defects in crystalline and amorphous silicon, Stone Wales defects in fullerenes and carbon nano-tubes, and the core structure of partial dislocations in some tetrahedral semiconductors. We investigate, using Density Functional Theory, two types of stoichiometry-conserving defects, which we call SCD and anti-SCD and which are metastable structures presenting five- and seven-membered rings, both in the cubic and in the hexagonal 4H-SiC polytypes. We also investigate the annealing properties of the two mentioned variants and find that one of them (SCD) easily disappears, turning back to a normal site, while the other (anti-SCD) transforms to an antisite pair, overcoming a barrier of 0. 21 eV. The very short lifetimes at ambient conditions explain why those defects have not been observed up to now, but they suggest they should be observable at very low temperature, and we provide local vibrational modes to facilitate their identification. (authors)

  14. Extended Active Disturbance Rejection Controller

    Science.gov (United States)

    Gao, Zhiqiang (Inventor); Tian, Gang (Inventor)

    2016-01-01

    Multiple designs, systems, methods and processes for controlling a system or plant using an extended active disturbance rejection control (ADRC) based controller are presented. The extended ADRC controller accepts sensor information from the plant. The sensor information is used in conjunction with an extended state observer in combination with a predictor that estimates and predicts the current state of the plant and a co-joined estimate of the system disturbances and system dynamics. The extended state observer estimates and predictions are used in conjunction with a control law that generates an input to the system based in part on the extended state observer estimates and predictions as well as a desired trajectory for the plant to follow.

  15. Scale-invariant extended inflation

    International Nuclear Information System (INIS)

    Holman, R.; Kolb, E.W.; Vadas, S.L.; Wang, Y.

    1991-01-01

    We propose a model of extended inflation which makes use of the nonlinear realization of scale invariance involving the dilaton coupled to an inflaton field whose potential admits a metastable ground state. The resulting theory resembles the Jordan-Brans-Dicke version of extended inflation. However, quantum effects, in the form of the conformal anomaly, generate a mass for the dilaton, thus allowing our model to evade the problems of the original version of extended inflation. We show that extended inflation can occur for a wide range of inflaton potentials with no fine-tuning of dimensionless parameters required. Furthermore, we also find that it is quite natural for the extended-inflation period to be followed by an epoch of slow-rollover inflation as the dilaton settles down to the minimum of its induced potential

  16. Defect CFTs and holographic multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Fiol, Bartomeu, E-mail: bfiol@ub.edu [Departament de Física Fonamental i Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès 1, 08193 Barcelona (Spain)

    2010-07-01

    We investigate some aspects of a recent proposal for a holographic description of the multiverse. Specifically, we focus on the implications on the suggested duality of the fluctuations of a bubble separating two universes with different cosmological constants. We do so by considering a similar problem in a 2+1 CFT with a codimension one defect, obtained by an M5-brane probe embedding in AdS{sub 4} × S{sup 7}, and studying its spectrum of fluctuations. Our results suggest that the kind of behavior required by the spectrum of bubble fluctuations is not likely to take place in defect CFTs with an AdS dual, although it might be possible if the defect supports a non-unitary theory.

  17. Stability and kinetics of point defects in SiO2 and in SiC

    International Nuclear Information System (INIS)

    Roma, G.

    2012-01-01

    This document is conceived as an overview of Guido Roma's research achievements on defects stability and kinetics in two materials of interest in nuclear science and for many other application domains: silicon dioxide and silicon carbide. An extended summary in french is followed by the main document, in english. Chapter 1 describes the context, introduces the approach and explains the choice of silicon dioxide and silicon carbide. Chapter 2 discusses several approximations and specific issues of the application of Density Functional Theory to point defects in non-metallic materials for the study of defects energetics and diffusion. Chapter 3 is devoted to native defects in silicon dioxide and the understanding of self-diffusion in crystalline and amorphous SiO 2 . Chapter 4 summarises the results on native defects and palladium impurities in silicon carbide. A conclusion, including suggestions for future developments, closes the main part of the document. (author) [fr

  18. Computed tomography angiography intraluminal filling defect is predictive of internal carotid artery free-floating thrombus

    Energy Technology Data Exchange (ETDEWEB)

    Jaberi, A.; Lum, C.; Stefanski, P.; Iancu, D. [University of Ottawa, Faculty of Medicine, Ottawa, Ontario (Canada); The Ottawa Hospital, Department of Radiology, Neuroradiology Section, Ottawa, Ontario (Canada); Thornhill, R. [Neurosciences and Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario (Canada); The Ottawa Hospital, Department of Radiology, Neuroradiology Section, Ottawa, Ontario (Canada); Petrcich, W. [Neurosciences and Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario (Canada); Momoli, F. [Children' s Hospital of Eastern Ontario Research Institute, Ottawa, Ontario (Canada); University of Ottawa, Department of Epidemiology and Community Medicine, Ottawa, Ontario (Canada); Torres, C.; Dowlatshahi, D. [University of Ottawa, Faculty of Medicine, Ottawa, Ontario (Canada); University of Ottawa, Division of Neurology, Department of Medicine, Ottawa, Ontario (Canada)

    2014-01-15

    Filling defects at the internal carotid artery (ICA) origin in the work-up of stroke or transient ischemic attack may be an ulcerated plaque or free-floating thrombus (FFT). This may be challenging to distinguish, as they can appear morphologically similar. This is an important distinction as FFT can potentially embolize distally, and its management differs. We describe a series of patients with suspected FFT and evaluate its imaging appearance, clinical features, and evolution with therapy. Between 2008 and 2013, we prospectively collected consecutive patients with proximal ICA filling defects in the axial plane surrounded by contrast on CT/MR angiography. We defined FFT as a filling defect that resolved on follow-up imaging. We assessed the cranial-caudal dimension of the filling defect and receiver operating characteristics to identify clinical and radiological variables that distinguished FFT from complex ulcerated plaque. Intraluminal filling defects were identified in 32 patients. Filling defects and resolved or decreased in 25 patients (78 %) and felt to be FFT; there was no change in 7 (22 %). Resolved defects and those that decreased in size extended more cranially than those that remained unchanged: 7.3 mm (4.2-15.9) versus 3.1 mm (2.7-3.7; p = 0.0038). Receiver operating characteristic analysis established a threshold of 3.8 mm (filling defect length), sensitivity of 88 %, specificity of 86 %, and area under the curve of 0.86 (p < 0.0001) for distinguishing FFT from plaque. Filling defects in the proximal ICA extending cranially >3.8 mm were more likely to be FFT than complex ulcerated plaque. Further studies evaluating filling defect length as a predictor for FFT are warranted. (orig.)

  19. Extended asymptotic functions - some examples

    International Nuclear Information System (INIS)

    Todorov, T.D.

    1981-01-01

    Several examples of extended asymptotic functions of two variables are given. This type of asymptotic functions has been introduced as an extension of continuous ordinary functions. The presented examples are realizations of some Schwartz distributions delta(x), THETA(x), P(1/xsup(n)) and can be multiplied in the class of the asymptotic functions as opposed to the theory of Schwartz distributions. The examples illustrate the method of construction of extended asymptotic functions similar to the distributions. The set formed by the extended asymptotic functions is also considered. It is shown, that this set is not closed with respect to addition and multiplication

  20. Cosmological dynamics of extended chameleons

    Energy Technology Data Exchange (ETDEWEB)

    Tamanini, Nicola [Institut de Physique Théorique, CEA-Saclay, CNRS UMR 3681, Université Paris-Saclay, F-91191 Gif-sur-Yvette (France); Wright, Matthew, E-mail: nicola.tamanini@cea.fr, E-mail: matthew.wright.13@ucl.ac.uk [Department of Mathematics, University College London, Gower Street, London, WC1E 6BT (United Kingdom)

    2016-04-01

    We investigate the cosmological dynamics of the recently proposed extended chameleon models at both background and linear perturbation levels. Dynamical systems techniques are employed to fully characterize the evolution of the universe at the largest distances, while structure formation is analysed at sub-horizon scales within the quasi-static approximation. The late time dynamical transition from dark matter to dark energy domination can be well described by almost all extended chameleon models considered, with no deviations from ΛCDM results at both background and perturbation levels. The results obtained in this work confirm the cosmological viability of extended chameleons as alternative dark energy models.

  1. Cosmological dynamics of extended chameleons

    International Nuclear Information System (INIS)

    Tamanini, Nicola; Wright, Matthew

    2016-01-01

    We investigate the cosmological dynamics of the recently proposed extended chameleon models at both background and linear perturbation levels. Dynamical systems techniques are employed to fully characterize the evolution of the universe at the largest distances, while structure formation is analysed at sub-horizon scales within the quasi-static approximation. The late time dynamical transition from dark matter to dark energy domination can be well described by almost all extended chameleon models considered, with no deviations from ΛCDM results at both background and perturbation levels. The results obtained in this work confirm the cosmological viability of extended chameleons as alternative dark energy models.

  2. Contribution of dynamic focusing to ultrasonic defect characterization

    International Nuclear Information System (INIS)

    Mahaut, S.

    1997-01-01

    Non destructive testing of vessels of pressurized water reactors uses ultrasonic focused transducers, with spherically shaped emitting surface or requiring an acoustic lens. But a mechanically focused transducer has to be used for a given inspection zone and for a fixed control configuration. The aim of this thesis is to improve ultrasonic defect characterization using adaptive dynamic focusing. Such a technique makes use of a ultrasonic defect characterization using adaptive dynamic focusing. Such a technique makes use of an ultrasonic transducer split into an array of individually controlled elements, allowing to apply delay and amplitude laws, calculated from modeling or experimentally deduced. Acoustical characteristics of the ultrasonic beam in the inspected specimen this can be electronically controlled; refraction angle, depth focusing, beam width. We briefly describe in the first chapter a theoretical modeling of the ultrasonic field radiated through a fluid/solid interface, extended to phase array transducers. This model is based on the integral formulation of Rayleigh, modified to take into account transmission through a fluid/solid (homogeneous and isotropic), of planar or cylindrical shape. In the second chapter an experimental study of this technique, with delay and amplitude laws given from the model, is presented, showing the efficiency of this method to adjust the acoustic performances. In he third chapter, experimental delay laws, extracted from the time distribution of signals received by the array (issued from a preliminary detected reflector), are used to provide an optimal imaging of the defect. This self-focusing procedure shows to adapt to a defect without using theoretical delays. The last chapter is dedicated to different applications devoted to improved defect characterization. The first application uses amplitude distribution received by the array, pointing out geometric characteristics of the reflector, while the second application

  3. Characterization of high-quality kerfless epitaxial silicon for solar cells: Defect sources and impact on minority-carrier lifetime

    Science.gov (United States)

    Kivambe, Maulid M.; Powell, Douglas M.; Castellanos, Sergio; Jensen, Mallory Ann; Morishige, Ashley E.; Lai, Barry; Hao, Ruiying; Ravi, T. S.; Buonassisi, Tonio

    2018-02-01

    We investigate the types and origins of structural defects in thin ( 105 cm-2 are observed. Cross-sectional and systematic plan-view defect etching and microscopy reveals that the majority of stacking faults and dislocations originate at the interface between the porous silicon layer and the epitaxial wafer. Localised dislocation clusters are observed in regions of collapsed/deformed porous silicon and at decorated stacking faults. In localized regions of high extended defect density, increased minority-carrier recombination activity is observed. Evidence for impurity segregation to the extended defects (internal gettering), which is known to exacerbate carrier recombination is demonstrated. The impact of the defects on material performance and substrate re-use is also discussed.

  4. Defect branes as Alice strings

    International Nuclear Information System (INIS)

    Okada, Takashi; Sakatani, Yuho

    2015-01-01

    There exist various defect-brane backgrounds in supergravity theories which arise as the low energy limit of string theories. These backgrounds typically have non-trivial monodromies, and if we move a charged probe around the center of a defect, its charge will be changed by the action of the monodromy. During the process, the charge conservation law seems to be violated. In this paper, to resolve this puzzle, we examine a dynamics of the charge changing process and show that the missing charge of the probe is transferred to the background. We then explicitly construct the resultant background after the charge transfer process by utilizing dualities. This background has the same monodromy as the original defect brane, but has an additional charge which does not have any localized source. In the literature, such a charge without localized source is known to appear in the presence of Alice strings. We argue that defect branes can in fact be regarded as a realization of Alice strings in string theory and examine the charge transfer process from that perspective.

  5. Space Mapping and Defect Correction

    NARCIS (Netherlands)

    D. Echeverria (David); D.J.P. Lahaye (Domenico); P.W. Hemker (Piet); W.H.A. Schilders (Wil); H.A. van der Vorst (Henk); J. Rommes

    2008-01-01

    textabstractIn this chapter we present the principles of the space-mapping iteration techniques for the efficient solution of optimization problems. We also show how space-mapping optimization can be understood in the framework of defect correction. We observe the difference between the solution

  6. Space mapping and defect correction

    NARCIS (Netherlands)

    Echeverría, D.; Lahaye, D.; Hemker, P.W.; Schilders, W.H.A.; van der Vorst, H.A.; Rommes, J.

    2008-01-01

    In this chapter we present the principles of the space-mapping iteration techniques for the efficient solution of optimization problems. We also show how space-mapping optimization can be understood in the framework of defect correction. We observe the difference between the solution of the

  7. Grassman defectivity à la Terracini

    Directory of Open Access Journals (Sweden)

    Carla Dionisi

    2001-11-01

    Full Text Available This work is a modern rivisitation of a classical paper by nA. Terracini, going back to 1915, which suggests an elementary but powerful method for studying Grassmann defective varieties. In particular, the case of Veronese surfaces is completely understood, giving a positive answer to the so-called Waring problem for pairs of homogeneous polynomials in three variables.

  8. Defects and an unusual superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gor' kov, L.P.; Kalugin, P.A.

    1985-03-10

    If the superconducting gap in a pure material has zeros on an entire line along the Fermi surface, the state density is finite at epsilon = 0, beginning with the lowest defect concentrations. The splitting of the superconducting transition by impurities, U/sub 1-x/Th/sub x/Be/sub 13/ is discussed.

  9. Delamination initiated by a defect

    DEFF Research Database (Denmark)

    Biel, Anders; Toftegaard, Helmuth Langmaack

    2016-01-01

    Composite materials in wind turbines are mainly joined with adhesives. Adhesive joining is preferable since it distributes the stresses over a larger area. This study shows how a defect can influence the fracture behaviour of adhesively joined composite. Repeated experiments are performed using d...

  10. Ocular defects in cerebral palsy

    Directory of Open Access Journals (Sweden)

    Katoch Sabita

    2007-01-01

    Full Text Available There is a high prevalence of ocular defects in children with developmental disabilities. This study evaluated visual disability in a group of 200 cerebral palsy (CP patients and found that 68% of the children had significant visual morbidity. These findings emphasize the need for an early ocular examination in patients with CP.

  11. Quasi-extended asymptotic functions

    International Nuclear Information System (INIS)

    Todorov, T.D.

    1979-01-01

    The class F of ''quasi-extended asymptotic functions'' is introduced. It contains all extended asymptotic functions as well as some new asymptotic functions very similar to the Schwartz distributions. On the other hand, every two quasiextended asymptotic functions can be multiplied as opposed to the Schwartz distributions; in particular, the square delta 2 of an asymptotic function delta similar to Dirac's delta-function, is constructed as an example

  12. Some problems with extended inflation

    International Nuclear Information System (INIS)

    Weinberg, E.J.

    1989-01-01

    The recently proposed extended inflation scenario is examined. Upper bounds on the Brans-Dicke parameter ω are obtained by requiring that the recovery from the supercooled regime be such that the presently observed Universe could have emerged. These bounds are well below the present-day experimental limits, implying that one must use models which have a potential to fix the present value of the Brans-Dicke-like scalar field. The implications for extended inflation in such models are discussed

  13. Extended likelihood inference in reliability

    International Nuclear Information System (INIS)

    Martz, H.F. Jr.; Beckman, R.J.; Waller, R.A.

    1978-10-01

    Extended likelihood methods of inference are developed in which subjective information in the form of a prior distribution is combined with sampling results by means of an extended likelihood function. The extended likelihood function is standardized for use in obtaining extended likelihood intervals. Extended likelihood intervals are derived for the mean of a normal distribution with known variance, the failure-rate of an exponential distribution, and the parameter of a binomial distribution. Extended second-order likelihood methods are developed and used to solve several prediction problems associated with the exponential and binomial distributions. In particular, such quantities as the next failure-time, the number of failures in a given time period, and the time required to observe a given number of failures are predicted for the exponential model with a gamma prior distribution on the failure-rate. In addition, six types of life testing experiments are considered. For the binomial model with a beta prior distribution on the probability of nonsurvival, methods are obtained for predicting the number of nonsurvivors in a given sample size and for predicting the required sample size for observing a specified number of nonsurvivors. Examples illustrate each of the methods developed. Finally, comparisons are made with Bayesian intervals in those cases where these are known to exist

  14. Extender for securing a closure

    Science.gov (United States)

    Thomas, II, Patrick A.

    2012-10-02

    An apparatus for securing a closure such as door or a window that opens and closes by movement relative to a fixed structure such as a wall or a floor. Many embodiments provide a device for relocating a padlock from its normal location where it secures a fastener (such as a hasp) to a location for the padlock that is more accessible for locking and unlocking the padlock. Typically an extender is provided, where the extender has a hook at a first end that is disposed through the eye of the staple of the hasp, and at an opposing second end the extender has an annulus, such as a hole in the extender or a loop or ring affixed to the extender. The shackle of the padlock may be disposed through the annulus and may be disposed through the eye of a second staple to secure the door or window in a closed or open position. Some embodiments employ a rigid sheath to enclose at least a portion of the extender. Typically the rigid sheath has an open state where the hook is exposed outside the sheath and a closed state where the hook is disposed within the sheath.

  15. Point defects and diffusion in alloys: correlation effects

    International Nuclear Information System (INIS)

    Barbe, Vincent

    2006-01-01

    Kinetic models in alloys aim at predicting the transport properties of a system starting from the microscopic jump frequencies of defects. Such properties are of prior importance in systems which stay out of equilibrium for a long time, as for example irradiated alloys in nuclear reactors. We hereby propose several developments of the recent self-consistent mean field (SCMF) kinetic theory, which deals particularly with the correlation effects due to the coupling of atomic and defect fluxes. They are taken into account through a non-equilibrium distribution function of the system, which is derived from the time evolution of small clusters (of two or more atoms or defects). We therefore introduce a set of 'dynamic' interactions called effective Hamiltonian. The SCMF theory is extended to treat high jump frequency ratios for the vacancy mechanism, as well as the transport through interstitial defects. We use in both cases an atomic model which accounts for the thermodynamic properties of the alloy, as e.g. the short-range order. Those models are eventually applied to predict the diffusion properties in two model alloys of nuclear interest: the concentrated Fe-Ni-Cr solid solution and the dilute Fe(P) alloy. We present adapted atomic models and compare our predictions to experimental data. (author)

  16. Predicting internal red oak (Quercus rubra) log defect features using surface defect defect measurements

    Science.gov (United States)

    R. Edward. Thomas

    2013-01-01

    Determining the defects located within a log is crucial to understanding the tree/log resource for efficient processing. However, existing means of doing this non-destructively requires the use of expensive x-ray/CT (computerized tomography), MRI (magnetic resonance imaging), or microwave technology. These methods do not lend themselves to fast, efficient, and cost-...

  17. EUV multilayer defect compensation (MDC) by absorber pattern modification: from theory to wafer validation

    Science.gov (United States)

    Pang, Linyong; Hu, Peter; Satake, Masaki; Tolani, Vikram; Peng, Danping; Li, Ying; Chen, Dongxue

    2011-11-01

    According to the ITRS roadmap, mask defects are among the top technical challenges to introduce extreme ultraviolet (EUV) lithography into production. Making a multilayer defect-free extreme ultraviolet (EUV) blank is not possible today, and is unlikely to happen in the next few years. This means that EUV must work with multilayer defects present on the mask. The method proposed by Luminescent is to compensate effects of multilayer defects on images by modifying the absorber patterns. The effect of a multilayer defect is to distort the images of adjacent absorber patterns. Although the defect cannot be repaired, the images may be restored to their desired targets by changing the absorber patterns. This method was first introduced in our paper at BACUS 2010, which described a simple pixel-based compensation algorithm using a fast multilayer model. The fast model made it possible to complete the compensation calculations in seconds, instead of days or weeks required for rigorous Finite Domain Time Difference (FDTD) simulations. Our SPIE 2011 paper introduced an advanced compensation algorithm using the Level Set Method for 2D absorber patterns. In this paper the method is extended to consider process window, and allow repair tool constraints, such as permitting etching but not deposition. The multilayer defect growth model is also enhanced so that the multilayer defect can be "inverted", or recovered from the top layer profile using a calibrated model.

  18. Radiation defects in α-iron: Structure and dynamics

    International Nuclear Information System (INIS)

    Dudarev, S.L.; Fitzgerald, S.P.; Lavrentiev, M.Y.; Nguyen-Manh, D.; Gilbert, M.R.; Yao, Z.; Jenkins, M.L.; Arakawa, K.; Mori, H.

    2009-01-01

    Microstructural evolution of materials under neutron irradiation is driven by the generation of defects in collision cascades and by their subsequent interaction, resulting in the agglomeration of defects and formation of mesoscopic defect structures, for example large dislocation loops and voids. The notion of dislocation bias, a concept central to the Rate Theory model, is a relatively simple means for including the effect of long-range elastic interactions between defects and dislocations in the treatment of microstructural evolution. The recently developed kinetic Monte-Carlo models, including the synchronous parallel implementations of the kinetic Monte-Carlo method, focus on the investigation of diffusive migration of defects, and treat interactions as short-range events occurring only if two defects get within a certain 'interaction radius' derived from either semi-phenomenological arguments or experimental observations. Observing interaction between single self-interstitial atom defects is still beyond the capability of modern electron microscopes. However, recent in-situ work showed that it is possible to observe, in real time, the effects of thermally activated, as well as electron beam stimulated, migration of small dislocation loops formed by the agglomeration of several self-interstitial defects. Furthermore, in-situ observations demonstrate that migrating dislocation loops interact. Depending on the orientation of their Burgers vectors the loops either repel or attract, in the latter case forming complexes where loops with the same Burgers vector line-up along a particular direction and then move coherently along their glide cylinders, held together over long period of time by the elastic forces. Observations show that this bound group-motion of loops generally occurs as a pre-cursor to the eventual coalescence of the loops resulting in the formation of extended dislocation lines. We investigate the formation of groups of 1/2 interstitial dislocation

  19. Charged Semiconductor Defects Structure, Thermodynamics and Diffusion

    CERN Document Server

    Seebauer, Edmund G

    2009-01-01

    The technologically useful properties of a solid often depend upon the types and concentrations of the defects it contains. Not surprisingly, defects in semiconductors have been studied for many years, in many cases with a view towards controlling their behavior through various forms of "defect engineering." For example, in the bulk, charging significantly affects the total concentration of defects that are available to mediate phenomena such as solid-state diffusion. Surface defects play an important role in mediating surface mass transport during high temperature processing steps such as epitaxial film deposition, diffusional smoothing in reflow, and nanostructure formation in memory device fabrication. Charged Semiconductor Defects details the current state of knowledge regarding the properties of the ionized defects that can affect the behavior of advanced transistors, photo-active devices, catalysts, and sensors. Features: Group IV, III-V, and oxide semiconductors; Intrinsic and extrinsic defects; and, P...

  20. Modeling defect trends for iterative development

    Science.gov (United States)

    Powell, J. D.; Spanguolo, J. N.

    2003-01-01

    The Employment of Defects (EoD) approach to measuring and analyzing defects seeks to identify and capture trends and phenomena that are critical to managing software quality in the iterative software development lifecycle at JPL.

  1. Extended Year, Extended Contracts: Increasing Teacher Salary Options.

    Science.gov (United States)

    Gandara, Patricia

    1992-01-01

    Reports on an attempt to raise teacher salaries through an extended contract made possible through year-round school schedules. Teacher satisfaction with the 1987 experiment in three California schools (the Orchard Plan) has been high. Elements that have contributed to job satisfaction are discussed. (SLD)

  2. Extended cognition in science communication.

    Science.gov (United States)

    Ludwig, David

    2014-11-01

    The aim of this article is to propose a methodological externalism that takes knowledge about science to be partly constituted by the environment. My starting point is the debate about extended cognition in contemporary philosophy and cognitive science. Externalists claim that human cognition extends beyond the brain and can be partly constituted by external devices. First, I show that most studies of public knowledge about science are based on an internalist framework that excludes the environment we usually utilize to make sense of science and does not allow the possibility of extended knowledge. In a second step, I argue that science communication studies should adopt a methodological externalism and accept that knowledge about science can be partly realized by external information resources such as Wikipedia. © The Author(s) 2013.

  3. Defects of mitochondrial DNA replication.

    Science.gov (United States)

    Copeland, William C

    2014-09-01

    Mitochondrial DNA is replicated by DNA polymerase γ in concert with accessory proteins such as the mitochondrial DNA helicase, single-stranded DNA binding protein, topoisomerase, and initiating factors. Defects in mitochondrial DNA replication or nucleotide metabolism can cause mitochondrial genetic diseases due to mitochondrial DNA deletions, point mutations, or depletion, which ultimately cause loss of oxidative phosphorylation. These genetic diseases include mitochondrial DNA depletion syndromes such as Alpers or early infantile hepatocerebral syndromes, and mitochondrial DNA deletion disorders, such as progressive external ophthalmoplegia, ataxia-neuropathy, or mitochondrial neurogastrointestinal encephalomyopathy. This review focuses on our current knowledge of genetic defects of mitochondrial DNA replication (POLG, POLG2, C10orf2, and MGME1) that cause instability of mitochondrial DNA and mitochondrial disease. © The Author(s) 2014.

  4. Cooperation and Defection in Ghetto

    Science.gov (United States)

    Kułakowski, Krzysztof

    We consider ghetto as a community of people ruled against their will by an external power. Members of the community feel that their laws are broken. However, attempts to leave ghetto makes their situation worse. We discuss the relation of the ghetto inhabitants to the ruling power in context of their needs, organized according to the Maslow hierarchy. Decisions how to satisfy successive needs are undertaken in cooperation with or defection the ruling power. This issue allows to construct the tree of decisions and to adopt the pruning technique from the game theory. Dynamics of decisions can be described within the formalism of fundamental equations. The result is that the strategy of defection is stabilized by the estimated payoff.

  5. Extrinsic point defects in aluminum antimonide

    OpenAIRE

    Erhart, Paul; Åberg, Daniel; Lordi, Vincenzo

    2010-01-01

    We investigate thermodynamic and electronic properties of group IV (C, Si, Ge, Sn) and group VI (O, S, Se, Te) impurities as well as P and H in aluminum antimonide (AlSb) using first-principles calculations. To this end, we compute the formation energies of a broad range of possible defect configurations including defect complexes with the most important intrinsic defects. We also obtain relative scattering cross strengths for these defects to determine their impact on charge carrier mobility...

  6. Iatrogenic Urethral Defect Repairment: A Case Report

    Directory of Open Access Journals (Sweden)

    Ulas Fidan

    2013-10-01

    Full Text Available    Iatrogenic urethral defect is a complication that occurs after vaginal surgical procedures. Many surgical methods according to place of defect are described in case of injury of urethra. In this article, we reported the repairment of distal urethral defect with the help of greft taken from labia minor. This defect is made by the excision of the granulation tissue that occurred after chronic paraurethral  gland infection.

  7. Defect relaxation in disordered materials

    International Nuclear Information System (INIS)

    Crandell, R.S.

    1989-01-01

    Using an exponential distribution of activation barriers, annealing data for metastable effects in hydrogenated amorphous silicon, a-Si:H, are quantitatively explained. This includes the stretched exponential time dependence of annealing and a Meyer-Neldel rule for the annealing time constant. An exponential distribution of annealing energies arises because defects are frozen in during growth at high temperature. Mechanisms that lead to an exponential distribution of annealing energies are weak bond-breaking and charge trapping

  8. Neonatal septum transversum diaphragmatic defects

    International Nuclear Information System (INIS)

    Wesselhoeft, C.W. Jr.; DeLuca, F.G.

    1984-01-01

    Over 10 years, 8 infants required surgery for central diaphragmatic herniation. Contrast peritoneography and technetium-99m-sulfur colloid radionuclide scanning were the most definitive diagnostic aids. Associated anomalies included variations of the pentalogy of Cantrell. A midline gastroduodenal loop was found in two infants. Six infants are alive and well 6 months to 3 years postoperatively. An abdominal approach is preferred if there is an intestinal hernia, associated gastrointestinal anomalies, or if a bilateral defect is present

  9. Neonatal septum transversum diaphragmatic defects

    Energy Technology Data Exchange (ETDEWEB)

    Wesselhoeft, C.W. Jr.; DeLuca, F.G.

    1984-04-01

    Over 10 years, 8 infants required surgery for central diaphragmatic herniation. Contrast peritoneography and technetium-99m-sulfur colloid radionuclide scanning were the most definitive diagnostic aids. Associated anomalies included variations of the pentalogy of Cantrell. A midline gastroduodenal loop was found in two infants. Six infants are alive and well 6 months to 3 years postoperatively. An abdominal approach is preferred if there is an intestinal hernia, associated gastrointestinal anomalies, or if a bilateral defect is present.

  10. Shear rheology of extended nanoparticles

    Science.gov (United States)

    Petersen, Matt K.; Lane, J. Matthew D.; Grest, Gary S.

    2010-07-01

    Nonequilibrium molecular-dynamics simulations are presented for the shear rheology of suspensions of extended “jack”-shaped nanoparticles in an explicit solvent. The shear viscosity is measured for two jack-shaped nanoparticle suspensions for volume fractions from 0.01 to 0.15 and compared to spherical nanoparticles of the same mass. Large differences, in some cases, orders of magnitude, are observed for both the equilibrium viscosity and diffusion constant as the shape of the nanoparticle is varied. The source of enhanced viscosity is the very large effective volume swept out by these extended nanoparticles which allows them to become highly entangled even at low volume fraction.

  11. Effective operators and extended symmetry

    CERN Document Server

    Frère, J M; Moreno, J M; Orloff, J

    1994-01-01

    In this note we expand on our previous study of the implications of LEP1 results for future colliders. We extend the effective operator-based analysis of De R\\'ujula et al. to a larger symmetry group, and show at which cost their expectations can be relaxed. Of particular interest to experiment is a rephrasing of our previous results in terms of the Renard et al. parametrization for the gauge boson self-couplings (slightly extended to include $\\delta g_{\\gamma}$). We suggest the use of a ($\\delta g_{\\gamma}$, $\\delta g_{Z}$) plot to confront the expectations of various models.

  12. Adjustable extender for instrument module

    International Nuclear Information System (INIS)

    Sevec, J.B.; Stein, A.D.

    1975-01-01

    A blank extender module used to mount an instrument module in front of its console for repair or test purposes has been equipped with a rotatable mount and means for locking the mount at various angles of rotation for easy accessibility. The rotatable mount includes a horizontal conduit supported by bearings within the blank module. The conduit is spring-biased in a retracted position within the blank module and in this position a small gear mounted on the conduit periphery is locked by a fixed pawl. The conduit and instrument mount can be pulled into an extended position with the gear clearing the pawl to permit rotation and adjustment of the instrument

  13. Exclusion Bounds for Extended Anyons

    Science.gov (United States)

    Larson, Simon; Lundholm, Douglas

    2018-01-01

    We introduce a rigorous approach to the many-body spectral theory of extended anyons, that is quantum particles confined to two dimensions that interact via attached magnetic fluxes of finite extent. Our main results are many-body magnetic Hardy inequalities and local exclusion principles for these particles, leading to estimates for the ground-state energy of the anyon gas over the full range of the parameters. This brings out further non-trivial aspects in the dependence on the anyonic statistics parameter, and also gives improvements in the ideal (non-extended) case.

  14. Curvature-Controlled Topological Defects

    Directory of Open Access Journals (Sweden)

    Luka Mesarec

    2017-05-01

    Full Text Available Effectively, two-dimensional (2D closed films exhibiting in-plane orientational ordering (ordered shells might be instrumental for the realization of scaled crystals. In them, ordered shells are expected to play the role of atoms. Furthermore, topological defects (TDs within them would determine their valence. Namely, bonding among shells within an isotropic liquid matrix could be established via appropriate nano-binders (i.e., linkers which tend to be attached to the cores of TDs exploiting the defect core replacement mechanism. Consequently, by varying configurations of TDs one could nucleate growth of scaled crystals displaying different symmetries. For this purpose, it is of interest to develop a simple and robust mechanism via which one could control the position and number of TDs in such atoms. In this paper, we use a minimal mesoscopic model, where variational parameters are the 2D curvature tensor and the 2D orientational tensor order parameter. We demonstrate numerically the efficiency of the effective topological defect cancellation mechanism to predict positional assembling of TDs in ordered films characterized by spatially nonhomogeneous Gaussian curvature. Furthermore, we show how one could efficiently switch among qualitatively different structures by using a relative volume v of ordered shells, which represents a relatively simple naturally accessible control parameter.

  15. Reflection and transmission for conformal defects

    NARCIS (Netherlands)

    Quella, T.; Runkel, I.; Watts, G.M.T.

    2007-01-01

    Abstract. We consider conformal defects joining two conformal field theories along a line. We define two new quantities associated to such defects in terms of expectation values of the stress tensors and we propose them as measures of the reflectivity and transmissivity of the defect. Their

  16. Metastable and bistable defects in silicon

    International Nuclear Information System (INIS)

    Mukashev, Bulat N; Abdullin, Kh A; Gorelkinskii, Yurii V

    2000-01-01

    Existing data on the properties and structure of metastable and bistable defects in silicon are analyzed. Primary radiation-induced defects (vacancies, self-interstitial atoms, and Frenkel pairs), complexes of oxygen, carbon, hydrogen, and other impurity atoms and defects with negative correlation energy are considered. (reviews of topical problems)

  17. Modeling charged defects, dopant diffusion and activation mechanisms for TCAD simulations using kinetic Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Bragado, Ignacio [Synopsys Inc, 700 East Middlefield Road, Mountain View, 94043 CA (United States)]. E-mail: Ignacio.martin-bragado@synopsys.com; Tian, S. [Synopsys Inc, 700 East Middlefield Road, Mountain View, 94043 CA (United States); Johnson, M. [Synopsys Inc, 700 East Middlefield Road, Mountain View, 94043 CA (United States); Castrillo, P. [Department of Electronics, University of Valladolid Campus Miguel Delibes, Camino del Cementerio S/N, 47011 Valladolid (Spain); Pinacho, R. [Department of Electronics, University of Valladolid Campus Miguel Delibes, Camino del Cementerio S/N, 47011 Valladolid (Spain); Rubio, J. [Department of Electronics, University of Valladolid Campus Miguel Delibes, Camino del Cementerio S/N, 47011 Valladolid (Spain); Jaraiz, M. [Department of Electronics, University of Valladolid Campus Miguel Delibes, Camino del Cementerio S/N, 47011 Valladolid (Spain)

    2006-12-15

    This work will show how the kinetic Monte Carlo (KMC) technique is able to successfully model the defects and diffusion of dopants in Si-based materials for advanced microelectronic devices, especially for non-equilibrium conditions. Charge states of point defects and paired dopants are also simulated, including the dependency of the diffusivities on the Fermi level and charged particle drift coming from the electric field. The KMC method is used to simulate the diffusion of the point defects, and formation and dissolution of extended defects, whereas a quasi-atomistic approach is used to take into account the carrier densities. The simulated mechanisms include the kick-out diffusion mechanism, extended defect formation and the activation/deactivation of dopants through the formation of impurity clusters. Damage accumulation and amorphization are also taken into account. Solid phase epitaxy regrowth is included, and also the dopants redistribution during recrystallization of the amorphized regions. Regarding the charged defects, the model considers the dependencies of charge reactions, electric bias, pairing and break-up reactions according to the local Fermi level. Some aspects of the basic physical mechanisms have also been taken into consideration: how to smooth out the atomistic dopant point charge distribution, avoiding very abrupt and unphysical charge profiles and how to implement the drift of charged particles into the existing electric field. The work will also discuss the efficiency, accuracy and relevance of the method, together with its implementation in a technology computer aided design process simulator.

  18. Prosthodontic Rehabilitation for Edentulous Patients With Palatal Defect: Report of Two Cases

    Directory of Open Access Journals (Sweden)

    Fen-Huey Lin

    2011-02-01

    Full Text Available Cancer resection is the most common cause of acquired palatal defects, whereas cleft palate is the main cause of congenital defects. Palatal defect can be repaired by reconstructive surgery and/or a dental prosthesis. We present prosthodontic rehabilitation of two maxillary edentulous patients, one with a surgically induced palatal defect and the other with congenital cleft palate. In case 1, an 86-year-old man underwent surgical removal of soft-palate squamous cell carcinoma. The acquired palatal defect was repaired by a maxillary complete denture with a posteriorly extended speech bulb. The final prostheses provided good chewing and speech functions. In case 2, a congenital cleft palate in a 65-year-old man was repaired by a maxillary complete denture with superior extension of the obturator, which was designed to improve retention and stability of the upper single denture. He was satisfied with the upper denture after prosthesis placement. Conventional maxillary complete denture with a posteriorly extended speech bulb or modified obturator provides a good chance to restore oral functions in patients with palatal defects. The patients' skill and previous experience of denture wearing might have been important in their successful treatment. However, different patients present with unique problems and need to be treated individually.

  19. Ideal and defective vertex configurations in the planar octagonal quasilattice

    Science.gov (United States)

    Baake, M.; Joseph, D.

    1990-11-01

    The well-known two-dimensional octagonal quasilattice is realized by means of dualization and Klotz construction. We discuss the geometric properties and the extended symmetry of the pattern. The concept of geometric defects is introduced, and an elastic energy measure ΔE is presented that allows a simple sequencing of the forbidden vertices. After a sketchy comparison with Lennard-Jones calculations, some thermodynamic consequences of ΔE are discussed. It turns out that the specific heat should show a significant increase in comparison with the crystallographic case.

  20. High contact angle hysteresis of superhydrophobic surfaces: Hydrophobic defects

    Science.gov (United States)

    Chang, Feng-Ming; Hong, Siang-Jie; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2009-08-01

    A typical superhydrophobic surface is essentially nonadhesive and exhibits very low water contact angle (CA) hysteresis, so-called Lotus effect. However, leaves of some plants such as scallion and garlic with an advancing angle exceeding 150° show very serious CA hysteresis. Although surface roughness and epicuticular wax can explain the very high advancing CA, our analysis indicates that the unusual hydrophobic defect, diallyl disulfide, is the key element responsible for contact line pinning on allium leaves. After smearing diallyl disulfide on an extended polytetrafluoroethylene (PTFE) film, which is originally absent of CA hysteresis, the surface remains superhydrophobic but becomes highly adhesive.

  1. Applying and extending Oracle Spatial

    CERN Document Server

    Simon Gerard Greener, Siva Ravada

    2013-01-01

    This book is an advanced practical guide to applying and extending Oracle Spatial.This book is for existing users of Oracle and Oracle Spatial who have, at a minimum, basic operational experience of using Oracle or an equivalent database. Advanced skills are not required.

  2. Ghosts in extended quasidilaton theories

    Science.gov (United States)

    Golovnev, Alexey; Trukhin, Aleksandr

    2017-11-01

    We report on our independent investigations of the puzzle of cosmological perturbations in extended quasidilaton. We confirm the claims of presence of the Boulware-Deser ghost. We use both the language of cosmological perturbations with broken diffeomorphisms and the Stückelberg approach.

  3. Extended memory management under RTOS

    Science.gov (United States)

    Plummer, M.

    1981-01-01

    A technique for extended memory management in ROLM 1666 computers using FORTRAN is presented. A general software system is described for which the technique can be ideally applied. The memory manager interface with the system is described. The protocols by which the manager is invoked are presented, as well as the methods used by the manager.

  4. Extended duration orbiter (EDO) insignia

    Science.gov (United States)

    1990-01-01

    Extended duration orbiter (EDO) insignia incorporates a space shuttle orbiter with payload bay doors (PLBDs) open and a spacelab module inside. Trailing the orbiter are the initials EDO. The EDO-modified Columbia, Orbiter Vehicle (OV) 102, will be flown for the first EDO mission, STS-50.

  5. Extended Duration Orbiter Medical Project

    Science.gov (United States)

    Leach, C. S.; Pool, S. L.; Sawin, C. F.; Nicogossian, A. E.

    1990-01-01

    The Extended Duration Orbiter (EDO) program addresses a need for more time to perform experiments and other tasks during Space Shuttle missions. As a part of this program, the Extended Duration Orbiter Medical Project (EDOMP) has been instituted to obtain information about physiologic effects of extending mission duration and the effectiveness of countermeasures against factors that might compromise crew health, safety, or performance on extended-duration missions. Only those investigations that address and characterize operational problems, develop countermeasures, or evaluate the effectiveness of countermeasures will be pursued. The EDOMP investigations will include flight-associated Detailed Supplementary Objectives as well as ground-based studies simulating the influence of microgravity. Investigator teams have been formed in the following areas: biomedical physiology, cardiovascular and fluid/electrolyte physiology, environmental health, muscle and exercise physiology, and neurophysiology. Major operational questions must be answered in each of these areas, and investigations have been designed to answer them. The EDO program will proceed only after countermeasures have been shown to be effective in preventing or mitigating the adverse changes they have been designed to attenuate. The program is underway and will continue on each Shuttle flight as the manifest builds toward a 16-day orbital flight.

  6. Extended unemployment and UI benefits

    OpenAIRE

    Robert G. Valletta; Katherine Kuang

    2010-01-01

    During the current labor market downturn, unemployment duration has reached levels well above its previous highs. Analysis of unemployment data suggests that extended unemployment insurance benefits have not been important factors in the increase in the duration of unemployment or in the elevated unemployment rate.

  7. Engage, Enhance, and Extend Learning!

    Science.gov (United States)

    Keren-Kolb, Liz

    2013-01-01

    Educators often say that technology is more than a gimmick or add-on, and that it should engage, enhance, or extend learning in ways that traditional tools do not. Yet they seldom stop to define these terms, and they can be confusing, especially for teachers and preservice teachers. Recently, while collaborating on an English language arts and…

  8. Preferential nucleation and growth of InAs/GaAs(0 0 1) quantum dots on defected sites by droplet epitaxy

    International Nuclear Information System (INIS)

    Chen, Z.B.; Lei, W.; Chen, B.; Wang, Y.B.; Liao, X.Z.; Tan, H.H.; Zou, J.; Ringer, S.P.; Jagadish, C.

    2013-01-01

    A double-layer InAs/GaAs(0 0 1) quantum dot structure grown by droplet epitaxy was found to have V-shaped defects, with the two arms of each defect originating from a buried quantum dot and extended to the top surface. Quantum dots on the sample surface nucleated and grew preferentially on top of the arms of the V-shaped defects. The mechanism behind the observed phenomenon was discussed

  9. Selecting the best defect reduction methodology

    Energy Technology Data Exchange (ETDEWEB)

    Hinckley, C.M. [Sandia National Labs., Albuquerque, NM (United States); Barkan, P. [Stanford Univ., CA (United States)

    1994-04-01

    Defect rates less than 10 parts per million, unimaginable a few years ago, have become the standard of world-class quality. To reduce defects, companies are aggressively implementing various quality methodologies, such as Statistical Quality Control Motorola`s Six Sigma, or Shingo`s poka-yok. Although each quality methodology reduces defects, selection has been based on an intuitive sense without understanding their relative effectiveness in each application. A missing link in developing superior defect reduction strategies has been a lack of a general defect model that clarifies the unique focus of each method. Toward the goal of efficient defect reduction, we have developed an event tree which addresses a broad spectrum of quality factors and two defect sources, namely, error and variation. The Quality Control Tree (QCT) predictions are more consistent with production experience than obtained by the other methodologies considered independently. The QCT demonstrates that world-class defect rates cannot be achieved through focusing on a single defect source or quality control factor, a common weakness of many methodologies. We have shown that the most efficient defect reduction strategy depend on the relative strengths and weaknesses of each organization. The QCT can help each organization identify the most promising defect reduction opportunities for achieving its goals.

  10. Lattice defects in ion-implanted aluminium studied by means of perturbed angular correlations. Pt. 1

    International Nuclear Information System (INIS)

    Pleiter, F.; Prasad, K.G.

    1984-01-01

    Migration and clustering of lattice defects after implantation of 111 In in Al and subsequent annealing at temperatures in the range from 80 to 800 K were investigated applying the DPAC technique. The effects of implantation dose, implantation temperature, laser irradiation, and plastic deformation were studied. The measurements on plastically deformed Al were complemented by positron lifetime measurements. Four In-defect clusters were observed that can be flagged by well-defined hyperfine interaction parameters, and their symmetry properties were determined by using single-crystal samples. Important conclusions are: (i) monovacancies are not trapped by In-atoms, (ii) small In-defect clusters are formed by direct trapping of divacancies and/or trivacancies, and (iii) extended In-defect clusters are very stable and anneal in the temperature range 600-700 K. Consequences for the interpretation of other measurements on dilute Al(In) alloys are discussed. (Auth.)

  11. Amorphous carbon film growth on Si: Correlation between stress and generation of defects into the substrate

    International Nuclear Information System (INIS)

    Brusa, R.S.; Macchi, C.; Mariazzi, S.; Karwasz, G.P.; Laidani, N.; Bartali, R.; Anderle, M.

    2005-01-01

    Amorphous carbon films of several thicknesses were prepared by graphite sputtering on crystalline silicon substrate. The samples were depth profiled with positron annihilation spectroscopy for open-volume measurements and characterized for their residual internal stress. It was found that after film growth the substrate presents vacancy-like defects decorated by oxygen in a layer extending in the substrate by several tens of nanometers beyond the film/Si interface. The width of the defected layer and the decoration of vacancy-like defects are directly and inversely proportional to the measured intensity of the residual stress, respectively. These findings indicate the existence of a relaxation mechanism of the stress in the films that involves deeply the substrate. The decorated vacancy-like defects are suggested to be bounded to dislocations induced in the substrate by the stress relaxation

  12. Investigating the Defect Structures in Transparent Conducting Oxides Using X-ray and Neutron Scattering Techniques.

    Science.gov (United States)

    González, Gabriela B

    2012-05-11

    Transparent conducting oxide (TCO) materials are implemented into a wide variety of commercial devices because they possess a unique combination of high optical transparency and high electrical conductivity. Created during the processing of the TCOs, defects within the atomic-scale structure are responsible for their desirable optical and electrical properties. Therefore, studying the defect structure is essential to a better understanding of the behavior of transparent conductors. X-ray and neutron scattering techniques are powerful tools to investigate the atomic lattice structural defects in these materials. This review paper presents some of the current developments in the study of structural defects in n-type TCOs using x-ray diffraction (XRD), neutron diffraction, extended x-ray absorption fine structure (EXAFS), pair distribution functions (PDFs), and x-ray fluorescence (XRF).

  13. Investigating the Defect Structures in Transparent Conducting Oxides Using X-ray and Neutron Scattering Techniques

    Directory of Open Access Journals (Sweden)

    Gabriela B. González

    2012-05-01

    Full Text Available Transparent conducting oxide (TCO materials are implemented into a wide variety of commercial devices because they possess a unique combination of high optical transparency and high electrical conductivity. Created during the processing of the TCOs, defects within the atomic-scale structure are responsible for their desirable optical and electrical properties. Therefore, studying the defect structure is essential to a better understanding of the behavior of transparent conductors. X-ray and neutron scattering techniques are powerful tools to investigate the atomic lattice structural defects in these materials. This review paper presents some of the current developments in the study of structural defects in n-type TCOs using x-ray diffraction (XRD, neutron diffraction, extended x-ray absorption fine structure (EXAFS, pair distribution functions (PDFs, and x-ray fluorescence (XRF.

  14. Yield impacting systematic defects search and management

    Science.gov (United States)

    Zhang, Jing; Xu, Qingxiu; Zhang, Xin; Zhao, Xing; Ning, Jay; Cheng, Guojie; Chen, Shijie; Zhang, Gary; Vikram, Abhishek; Su, Bo

    2012-03-01

    Despite great effort before design tapeout, there are still some pattern related systematic defects showing up in production, which impact product yield. Through various check points in the production life cycle endeavor is made to detect these defective patterns. It is seen that apart from the known defective patterns, slight variations of polygon sizes and shapes in the known defective patterns also cause yield loss. This complexity is further compounded when interactions among multiple process layers causes the defect. Normally the exact pattern matching techniques cannot detect these variations of the defective patterns. With the currently existing tools in the fab it is a challenge to define the 'sensitive patterns', which are arbitrary variations in the known 'defective patterns'. A design based approach has been successfully experimented on product wafers to detect yield impacting defects that greatly reduces the TAT for hotspot analysis and also provides optimized care area definition to enable high sensitivity wafer inspection. A novel Rule based pattern search technique developed by Anchor Semiconductor has been used to find sensitive patterns in the full chip design. This technique allows GUI based pattern search rule generation like, edge move or edge-to-edge distance range, so that any variations of a particular sensitive pattern can be captured and flagged. Especially the pattern rules involving multiple process layers, like M1-V1-M2, can be defined easily using this technique. Apart from using this novel pattern search technique, design signatures are also extracted around the defect locations in the wafer and used in defect classification. This enhanced defect classification greatly helps in determining most critical defects among the total defect population. The effectiveness of this technique has been established through design to defect correlation and SEM verification. In this paper we will report details of the design based experiments that

  15. If Your Child Has a Heart Defect (For Parents)

    Science.gov (United States)

    ... ventricular septal defect , truncus arteriosus, atrioventricular septal defect, tetralogy of Fallot , and transposition of the great arteries) can be ... Care and Your Newborn Coarctation of the Aorta Tetralogy of Fallot Atrial Septal Defect Ventricular Septal Defect When Your ...

  16. Impact of dopant profiles on the end of range defects for low energy germanium preamorphized silicon

    International Nuclear Information System (INIS)

    Camillo-Castillo, R.A.; Law, M.E.; Jones, K.S.

    2004-01-01

    As the industry continues to aggressively scale CMOS technology, the shift to lower energy ion implantation becomes essential. The consequent shallower amorphous layers result in dopant profiles that are in closer proximity to the end of range (EOR) damage and therefore a better understanding of the interaction between the dopant atoms and the EOR is required. A study is conducted on the influence of dopant profiles on the behavior of the EOR defects. Czochralski-grown silicon wafers are preamorphized with 1 x 10 15 cm -2 , 10 keV Ge + ions and subsequently implanted with 1 x 10 15 cm -2 , 1 keV B + ions. A sequence of rapid thermal and furnace anneals are performed at 750 deg. C under a nitrogen ambient for periods of 1 s up to 6 h. Plan view transmission electron microscopy (PTEM) reveals a significant difference in the defect evolution for samples with and without boron, suggesting that the boron influences the evolution of the EOR defects. The extended defects observed for samples which contain boron appear as dot-like defects which are unstable and dissolve after very short anneal times. The defect evolution however, in samples without boron follows an Oswald ripening behavior and form {3 1 1}-type defects and dislocation loops. Hall effect measurements denote a high initial activation and subsequent deactivation of the dopant atoms which is characteristic of the formation of boron interstitial clusters. Diffusion analyses via secondary ion mass spectroscopy (SIMS) support this theory

  17. Packing defects into ordered structures

    DEFF Research Database (Denmark)

    Bechstein, R.; Kristoffersen, Henrik Høgh; Vilhelmsen, L.B.

    2012-01-01

    We have studied vicinal TiO2(110) surfaces by high-resolution scanning tunneling microscopy and density functional theory calculations. On TiO2 surfaces characterized by a high density of ⟨11̅ 1⟩ steps, scanning tunneling microscopy reveals a high density of oxygen-deficient strandlike adstructures....... With the help of density functional theory calculations we develop a complete structural model for the entire strand and demonstrate these adstructures to be more stable than an equivalent amount of bulk defects such as Ti interstitials. We argue that strands can form particularly easy on stepped surfaces...

  18. Departies: conceptualizing extended youth parties

    DEFF Research Database (Denmark)

    Fjær, Eivind Grip; Tutenges, Sébastien

    2017-01-01

    Every year, millions of young people travel away from home to party for days or weeks on end in permissive environments, such as music festivals, dance parties, and nightlife resorts. The studies that have been conducted on these extended youth parties have focused primarily on specific risk......-taking behaviors, such as drug use and violence. Here, we scrutinize the research on extended youth parties to identify general changes that young people undergo at these events. We call these celebrations departies, because they center on the organization and facilitation of momentary departures from...... immoral; (4) stylistically, by altering their stylistic expressions through dress, demeanor, and consumption; and (5) experientially, because the parties generate mood and mind alterations. These are overlapping and intertwined elements, the combination of which amounts to a distinct type of youth party...

  19. Non-invasive extending prosthesis

    OpenAIRE

    Meswania, Jayantilal Mohanlal

    2006-01-01

    Most sarcomas of the bone occur in patients of a relatively young age including skeletally immature patients. Approximately 50 child sarcomas are treated with limb salvage surgery per year in the United Kingdom. These children need an extendible implant that can be lengthened periodically to keep pace with the growth in the opposite limb. Surgically, invasive devices have been used for the past thirty years with intrinsic problems of infection and long-term recurrent trauma to the patient. To...

  20. Black holes from extended inflation

    International Nuclear Information System (INIS)

    Hsu, S.D.H.; Lawrence Berkeley Lab., CA

    1990-01-01

    It is argued that models of extended inflation, in which modified Einstein gravity allows a graceful exit from the false vacuum, lead to copious production of black holes. The critical temperature of the inflationary phase transition must be >10 8 GeV in order to avoid severe cosmological problems in a universe dominated by black holes. We speculate on the possibility that the interiors of false vacuum regions evolve into baby universes. (orig.)

  1. Locating and extending livelihoods research

    DEFF Research Database (Denmark)

    Prowse, Martin

    2008-01-01

    Much poverty and development research is not explicit about its methodology or philosophical foundations. Based on the extended case method of Burawoy and the epistemological standpoint of critical realism, this paper discusses a methodological approach for reflexive inductive livelihoods researc...... that overcomes the unproductive social science dualism of positivism and social constructivism. The approach is linked to a conceptual framework and a menu of research methods that can be sequenced and iterated in light of research questions....

  2. Extended producer responsibility in oligopoly

    OpenAIRE

    Hiroaki Ino

    2007-01-01

    I investigate the optimal environmental tax under a policy based on extended producer responsibility (EPR) in oligopoly markets. I introduce the recycling market and explicitly consider how these policies affect the incentive for recycling. I derive the optimal tax rule, which depends on the weighted sum of the markup in the product market and the markdown in the recycling market. In contrast to the existing works that emphasize that the optimal tax rate is lower than the marginal external da...

  3. Liquid exfoliation of defect-free graphene.

    Science.gov (United States)

    Coleman, Jonathan N

    2013-01-15

    Due to its unprecedented physical properties, graphene has generated huge interest over the last 7 years. Graphene is generally fabricated in one of two ways: as very high quality sheets produced in limited quantities by micromechanical cleavage or vapor growth or as a rather defective, graphene-like material, graphene oxide, produced in large quantities. However, a growing number of applications would profit from the availability of a method to produce high-quality graphene in large quantities. This Account describes recent work to develop such a processing route inspired by previous theoretical and experimental studies on the solvent dispersion of carbon nanotubes. That work had shown that nanotubes could be effectively dispersed in solvents whose surface energy matched that of the nanotubes. We describe the application of the same approach to the exfoliation of graphite to give graphene in a range of solvents. When graphite powder is exposed to ultrasonication in the presence of a suitable solvent, the powder fragments into nanosheets, which are stabilized against aggregation by the solvent. The enthalpy of mixing is minimized for solvents with surface energies close to that of graphene (∼68 mJ/m(2)). The exfoliated nanosheets are free of defects and oxides and can be produced in large quantities. Once solvent exfoliation is possible, the process can be optimized and the nanosheets can be separated by size. The use of surfactants can also stabilize exfoliated graphene in water, where the ζ potential of the surfactant-coated graphene nanosheets controls the dispersed concentration. Liquid exfoliated graphene can be used for a range of applications: graphene dispersions as optical limiters, films of graphene flakes as transparent conductors or sensors, and exfoliated graphene as a mechanical reinforcement for polymer-based composites. Finally, we have extended this process to exfoliate other layered compounds such as BN and MoS(2). Such materials will be

  4. Magnetoencephalography signals are influenced by skull defects.

    Science.gov (United States)

    Lau, S; Flemming, L; Haueisen, J

    2014-08-01

    Magnetoencephalography (MEG) signals had previously been hypothesized to have negligible sensitivity to skull defects. The objective is to experimentally investigate the influence of conducting skull defects on MEG and EEG signals. A miniaturized electric dipole was implanted in vivo into rabbit brains. Simultaneous recording using 64-channel EEG and 16-channel MEG was conducted, first above the intact skull and then above a skull defect. Skull defects were filled with agar gels, which had been formulated to have tissue-like homogeneous conductivities. The dipole was moved beneath the skull defects, and measurements were taken at regularly spaced points. The EEG signal amplitude increased 2-10 times, whereas the MEG signal amplitude reduced by as much as 20%. The EEG signal amplitude deviated more when the source was under the edge of the defect, whereas the MEG signal amplitude deviated more when the source was central under the defect. The change in MEG field-map topography (relative difference measure, RDM(∗)=0.15) was geometrically related to the skull defect edge. MEG and EEG signals can be substantially affected by skull defects. MEG source modeling requires realistic volume conductor head models that incorporate skull defects. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  5. Topological Defects in a Living Nematic Ensnare Swimming Bacteria

    Directory of Open Access Journals (Sweden)

    Mikhail M. Genkin

    2017-03-01

    Full Text Available Active matter exemplified by suspensions of motile bacteria or synthetic self-propelled particles exhibits a remarkable propensity to self-organization and collective motion. The local input of energy and simple particle interactions often lead to complex emergent behavior manifested by the formation of macroscopic vortices and coherent structures with long-range order. A realization of an active system has been conceived by combining swimming bacteria and a lyotropic liquid crystal. Here, by coupling the well-established and validated model of nematic liquid crystals with the bacterial dynamics, we develop a computational model describing intricate properties of such a living nematic. In faithful agreement with the experiment, the model reproduces the onset of periodic undulation of the director and consequent proliferation of topological defects with the increase in bacterial concentration. It yields a testable prediction on the accumulation of bacteria in the cores of +1/2 topological defects and depletion of bacteria in the cores of -1/2 defects. Our dedicated experiment on motile bacteria suspended in a freestanding liquid crystalline film fully confirms this prediction. Our findings suggest novel approaches for trapping and transport of bacteria and synthetic swimmers in anisotropic liquids and extend a scope of tools to control and manipulate microscopic objects in active matter.

  6. Dopants and defects in semiconductors

    CERN Document Server

    McCluskey, Matthew D

    2012-01-01

    "The book goes beyond the usual textbook in that it provides more specific examples of real-world defect physics … The book will be most useful for beginning graduate students in materials science. … an easy reading, broad introductory overview of the field …"-Materials Today, July-August 2012"… well written, with clear, lucid explanations …"-Chemistry World"The scientific development towards the method of controllable doping transformed the erratic and not reproducible family of semiconductor materials into the truly wonderful basis of modern microelectronics. This book tells the remarkable success story and I recommend it!"-Hans J. Queisser, Max-Planck-Institute, Stuttgart, Germany"McCluskey and Haller have written an outstanding modern guide to this field that will be useful to newcomers, and also to active researchers who want to broaden their horizons, as a means to learn the capabilities and limitations of the many techniques that are used in semiconductor-defect science."-Professor Michael J....

  7. Computational techniques for determining printability of real defects in EUV mask pilot line

    Science.gov (United States)

    Morgan, Paul; Rost, Daniel; Price, Daniel; Li, Ying; Peng, Daniel; Chen, Dongxue; Hu, Peter; Corcoran, Noel; Son, Donghwan; Yonenaga, Dean; Tolani, Vikram

    2014-04-01

    With EUV lithography on the ITRS roadmap for sub-2X half-pitch patterning, it has become increasingly essential to ramp up efforts in being able to manufacture defect-free reticles or at least ones with minimal defects initially. For this purpose, much of the focus in recent years has been in finding ways to adequately detect, characterize, and reduce defects on both EUV blanks and patterned masks. For detection purposes, the current high-resolution DUV or e-beam inspection platforms are being extended to inspect EUV blanks and patterned masks but being non-actinic, make it very challenging to assess the real impact of the detected defects on EUV plane. Even with the realization of the EUV beta AIMS™ aerial-image based metrology in 2014-2015, the exact nature of each critical defect needs to be determined in order to be able to come up with an appropriate repair strategy. In this paper, we demonstrate the application of computational techniques to non-actinic supplemental metrology data collected on EUV mask defects to effectively determine the nature and also predict printability of these defects. The fundamental EUV simulation engine used in this approach is the EUV Defect Printability Simulator (DPS), which uses simulation and modeling methods designed specifically for the individual EUV mask components, and achieves runtimes several orders of magnitude faster than rigorous FDTD and RCWA methods while maintaining adequate accuracy. The EUV DPS simulator is then coupled with supplemental inspection and metrology measurements of real defects to effectively predict wafer printability of these defects. Several sources of such supplementary data are explored here, and may sometimes be dependent on the actual nature of defect. These sources include AFM height-profile data, SEM top-down images, and 193nm high-NA inspection images of single or multiple focus plane capture. From each of these supplemental data sources, the mask pattern and defect information is first

  8. Defects and diffusion in Si+ implanted GaAs

    International Nuclear Information System (INIS)

    Jones, K.S.; Robinson, H.G.; Deal, M.D.; Lee, C.C.; Allen, E.L.

    1993-05-01

    The effect of extended defects on the diffusion of ion implanted species is an area of concern in the development of process simulators for GaAs. This study explores the effect of type 1 extended defects including voids and dislocation loops on the diffusion of Si implanted into GaAs. Semi-insulating GaAs wafers were implanted with 1 x 10 14 /cm 2 Si + at implant temperatures between -51 C and 80 C and at energies ranging from 20 keV to 200 keV. SIMS results show that the diffusivity of Si decreases with both increasing implant temperature and increasing implant energy. At the same time extrinsic dislocation loop concentrations also increased. For the implant conditions studied, no voids were observed. The diffusion results can only be reconciled with the TEM results if the dislocation loops are behaving in a reactive rather than proactive manner. In other words, the changes in vacancy concentration that are affecting the diffusivity are also affecting the loop concentration. This model is supported by evidence that Si diffusivity is enhanced over the same time interval the dislocation loops are dissolving which is consistent with the loops having a reactive role. It remains unclear whether the existence of loops significantly affects the total concentration of vacancies and thus diffusion by acting as a competing sink

  9. Perception of risk from automobile safety defects.

    Science.gov (United States)

    Slovic, P; MacGregor, D; Kraus, N N

    1987-10-01

    Descriptions of safety engineering defects of the kind that compel automobile manufacturers to initiate a recall campaign were evaluated by individuals on a set of risk characteristic scales that included overall vehicle riskiness, manufacturer's ability to anticipate the defect, importance for vehicle operation, severity of consequences and likelihood of compliance with a recall notice. A factor analysis of the risk characteristics indicated that judgments could be summarized in terms of two composite scales, one representing the uncontrollability of the damage the safety defect might cause and the other representing the foreseeability of the defect by the manufacturer. Motor vehicle defects were found to be highly diverse in terms of the perceived qualities of their risks. Location of individual defects within the factor space was closely associated with perceived riskiness, perceived likelihood of purchasing another car from the same manufacturer, perceived likelihood of compliance with a recall notice, and actual compliance rates.

  10. Altering graphene line defect properties using chemistry

    Science.gov (United States)

    Vasudevan, Smitha; White, Carter; Gunlycke, Daniel

    2012-02-01

    First-principles calculations are presented of a fundamental topological line defect in graphene that was observed and reported in Nature Nanotech. 5, 326 (2010). These calculations show that atoms and smaller molecules can bind covalently to the surface in the vicinity of the graphene line defect. It is also shown that the chemistry at the line defect has a strong effect on its electronic and magnetic properties, e.g. the ferromagnetically aligned moments along the line defect can be quenched by some adsorbates. The strong effect of the adsorbates on the line defect properties can be understood by examining how these adsorbates affect the boundary-localized states in the vicinity of the Fermi level. We also expect that the line defect chemistry will significantly affect the scattering properties of incident low-energy particles approaching it from graphene.

  11. Automatic classification of defects in weld pipe

    International Nuclear Information System (INIS)

    Anuar Mikdad Muad; Mohd Ashhar Hj Khalid; Abdul Aziz Mohamad; Abu Bakar Mhd Ghazali; Abdul Razak Hamzah

    2000-01-01

    With the advancement of computer imaging technology, the image on hard radiographic film can be digitized and stored in a computer and the manual process of defect recognition and classification may be replace by the computer. In this paper a computerized method for automatic detection and classification of common defects in film radiography of weld pipe is described. The detection and classification processes consist of automatic selection of interest area on the image and then classify common defects using image processing and special algorithms. Analysis of the attributes of each defect such as area, size, shape and orientation are carried out by the feature analysis process. These attributes reveal the type of each defect. These methods of defect classification result in high success rate. Our experience showed that sharp film images produced better results

  12. Intrinsic point defects in aluminum antimonide

    OpenAIRE

    Åberg, Daniel; Erhart, Paul; Williamson, Andrew J.; Lordi, Vincenzo

    2010-01-01

    Calculations within density functional theory on the basis of the local density approximation are carried out to study the properties of intrinsic point defects in aluminum antimonide. Special care is taken to address finite-size effects, band gap error, and symmetry reduction in the defect structures. The correction of the band gap is based on a set of GW calculations. The most important defects are identified to be the aluminum interstitial $Al_{i,Al}^{1+}$, the antimony antisites $Sb_{Al}^...

  13. Diffusional changes of defect structure in solids

    International Nuclear Information System (INIS)

    Lyubov, B.Ya.

    1982-01-01

    Some problems of the theory of vacancy and impurity atoms diffusion in structure heterogeneous solidsi connected with changes in their defect structure, are reviewed. Two aspects of changes in the defect structure are discussed: an unconcervative movement of dislocations and a growth of damage of material continuity. Analytical solution methods in the theory of diffusional changes of defect structure in solids are illustrated as applied to hydrogen corrosion in steels, sintering kinetics, thermal conductivity theory [ru

  14. Phosphorous–vacancy–oxygen defects in silicon

    KAUST Repository

    Wang, Hao

    2013-07-30

    Electronic structure calculations employing the hybrid functional approach are used to gain fundamental insight in the interaction of phosphorous with oxygen interstitials and vacancies in silicon. It recently has been proposed, based on a binding energy analysis, that phosphorous–vacancy–oxygen defects may form. In the present study we investigate the stability of this defect as a function of the Fermi energy for the possible charge states. Spin polarization is found to be essential for the charge neutral defect.

  15. Effects of mass defect in atomic clocks

    Science.gov (United States)

    Taichenachev, A. V.; Yudin, V. I.

    2018-01-01

    We consider some implications of the mass defect on the frequency of atomic transitions. We have found that some well-known frequency shifts (such as gravitational and quadratic Doppler shifts) can be interpreted as consequences of the mass defect, i.e., without the need for the concept of time dilation used in special and general relativity theories. Moreover, we show that the inclusion of the mass defect leads to previously unknown shifts for clocks based on trapped ions..

  16. Effect of implanted species on thermal evolution of ion-induced defects in ZnO

    International Nuclear Information System (INIS)

    Azarov, A. Yu.; Rauwel, P.; Kuznetsov, A. Yu.; Svensson, B. G.; Hallén, A.; Du, X. L.

    2014-01-01

    Implanted atoms can affect the evolution of ion-induced defects in radiation hard materials exhibiting a high dynamic annealing and these processes are poorly understood. Here, we study the thermal evolution of structural defects in wurtzite ZnO samples implanted at room temperature with a wide range of ion species (from 11 B to 209 Bi) to ion doses up to 2 × 10 16  cm −2 . The structural disorder was characterized by a combination of Rutherford backscattering spectrometry, nuclear reaction analysis, and transmission electron microscopy, while secondary ion mass spectrometry was used to monitor the behavior of both the implanted elements and residual impurities, such as Li. The results show that the damage formation and its thermal evolution strongly depend on the ion species. In particular, for F implanted samples, a strong out-diffusion of the implanted ions results in an efficient crystal recovery already at 600 °C, while co-implantation with B (via BF 2 ) ions suppresses both the F out-diffusion and the lattice recovery at such low temperatures. The damage produced by heavy ions (such as Cd, Au, and Bi) exhibits a two-stage annealing behavior where efficient removal of point defects and small defect clusters occurs at temperatures ∼500 °C, while the second stage is characterized by a gradual and partial annealing of extended defects. These defects can persist even after treatment at 900 °C. In contrast, the defects produced by light and medium mass ions (O, B, and Zn) exhibit a more gradual annealing with increasing temperature without distinct stages. In addition, effects of the implanted species may lead to a nontrivial defect evolution during the annealing, with N, Ag, and Er as prime examples. In general, the obtained results are interpreted in terms of formation of different dopant-defect complexes and their thermal stability

  17. Electron beam generation and structure of defects in carbon and boron nitride nano-tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zobelli, A

    2007-10-15

    The nature and role of defects is of primary importance to understand the physical properties of C and BN (boron nitride) single walled nano-tubes (SWNTs). Transmission electron microscopy (TEM) is a well known powerful tool to study the structure of defects in materials. However, in the case of SWNTs, the electron irradiation of the TEM may knock out atoms. This effect may alter the native structure of the tube, and has also been proposed as a potential tool for nano-engineering of nano-tubular structures. Here we develop a theoretical description of the irradiation mechanism. First, the anisotropy of the emission energy threshold is obtained via density functional based calculations. Then, we numerically derive the total Mott cross section for different emission sites of carbon and boron nitride nano-tubes with different chiralities. Using a dedicated STEM (Scanning Transmission Electron Microscope) microscope with experimental conditions optimised on the basis of derived cross-sections, we are able to control the generation of defects in nano-tubular systems. Either point or line defects can be obtained with a spatial resolution of a few nanometers. The structure, energetics and electronics of point and line defects in BN systems have been investigated. Stability of mono- and di- vacancy defects in hexagonal boron nitride layers is investigated, and their activation energies and reaction paths for diffusion have been derived using the nudged elastic band method (NEB) combined with density functional based techniques. We demonstrate that the appearance of extended linear defects under electron irradiation is more favorable than a random distribution of point defects and this is due to the existence of preferential sites for atom emission in the presence of pre-existing defects, rather than thermal vacancy nucleation and migration. (author)

  18. Effect of implanted species on thermal evolution of ion-induced defects in ZnO

    Science.gov (United States)

    Azarov, A. Yu.; Hallén, A.; Du, X. L.; Rauwel, P.; Kuznetsov, A. Yu.; Svensson, B. G.

    2014-02-01

    Implanted atoms can affect the evolution of ion-induced defects in radiation hard materials exhibiting a high dynamic annealing and these processes are poorly understood. Here, we study the thermal evolution of structural defects in wurtzite ZnO samples implanted at room temperature with a wide range of ion species (from 11B to 209Bi) to ion doses up to 2 × 1016 cm-2. The structural disorder was characterized by a combination of Rutherford backscattering spectrometry, nuclear reaction analysis, and transmission electron microscopy, while secondary ion mass spectrometry was used to monitor the behavior of both the implanted elements and residual impurities, such as Li. The results show that the damage formation and its thermal evolution strongly depend on the ion species. In particular, for F implanted samples, a strong out-diffusion of the implanted ions results in an efficient crystal recovery already at 600 °C, while co-implantation with B (via BF2) ions suppresses both the F out-diffusion and the lattice recovery at such low temperatures. The damage produced by heavy ions (such as Cd, Au, and Bi) exhibits a two-stage annealing behavior where efficient removal of point defects and small defect clusters occurs at temperatures ˜500 °C, while the second stage is characterized by a gradual and partial annealing of extended defects. These defects can persist even after treatment at 900 °C. In contrast, the defects produced by light and medium mass ions (O, B, and Zn) exhibit a more gradual annealing with increasing temperature without distinct stages. In addition, effects of the implanted species may lead to a nontrivial defect evolution during the annealing, with N, Ag, and Er as prime examples. In general, the obtained results are interpreted in terms of formation of different dopant-defect complexes and their thermal stability.

  19. Computed tomography angiography intraluminal filling defect is predictive of internal carotid artery free-floating thrombus

    International Nuclear Information System (INIS)

    Jaberi, A.; Lum, C.; Stefanski, P.; Iancu, D.; Thornhill, R.; Petrcich, W.; Momoli, F.; Torres, C.; Dowlatshahi, D.

    2014-01-01

    Filling defects at the internal carotid artery (ICA) origin in the work-up of stroke or transient ischemic attack may be an ulcerated plaque or free-floating thrombus (FFT). This may be challenging to distinguish, as they can appear morphologically similar. This is an important distinction as FFT can potentially embolize distally, and its management differs. We describe a series of patients with suspected FFT and evaluate its imaging appearance, clinical features, and evolution with therapy. Between 2008 and 2013, we prospectively collected consecutive patients with proximal ICA filling defects in the axial plane surrounded by contrast on CT/MR angiography. We defined FFT as a filling defect that resolved on follow-up imaging. We assessed the cranial-caudal dimension of the filling defect and receiver operating characteristics to identify clinical and radiological variables that distinguished FFT from complex ulcerated plaque. Intraluminal filling defects were identified in 32 patients. Filling defects and resolved or decreased in 25 patients (78 %) and felt to be FFT; there was no change in 7 (22 %). Resolved defects and those that decreased in size extended more cranially than those that remained unchanged: 7.3 mm (4.2-15.9) versus 3.1 mm (2.7-3.7; p = 0.0038). Receiver operating characteristic analysis established a threshold of 3.8 mm (filling defect length), sensitivity of 88 %, specificity of 86 %, and area under the curve of 0.86 (p 3.8 mm were more likely to be FFT than complex ulcerated plaque. Further studies evaluating filling defect length as a predictor for FFT are warranted. (orig.)

  20. Electron beam generation and structure of defects in carbon and boron nitride nano-tubes

    International Nuclear Information System (INIS)

    Zobelli, A.

    2007-10-01

    The nature and role of defects is of primary importance to understand the physical properties of C and BN (boron nitride) single walled nano-tubes (SWNTs). Transmission electron microscopy (TEM) is a well known powerful tool to study the structure of defects in materials. However, in the case of SWNTs, the electron irradiation of the TEM may knock out atoms. This effect may alter the native structure of the tube, and has also been proposed as a potential tool for nano-engineering of nano-tubular structures. Here we develop a theoretical description of the irradiation mechanism. First, the anisotropy of the emission energy threshold is obtained via density functional based calculations. Then, we numerically derive the total Mott cross section for different emission sites of carbon and boron nitride nano-tubes with different chiralities. Using a dedicated STEM (Scanning Transmission Electron Microscope) microscope with experimental conditions optimised on the basis of derived cross-sections, we are able to control the generation of defects in nano-tubular systems. Either point or line defects can be obtained with a spatial resolution of a few nanometers. The structure, energetics and electronics of point and line defects in BN systems have been investigated. Stability of mono- and di- vacancy defects in hexagonal boron nitride layers is investigated, and their activation energies and reaction paths for diffusion have been derived using the nudged elastic band method (NEB) combined with density functional based techniques. We demonstrate that the appearance of extended linear defects under electron irradiation is more favorable than a random distribution of point defects and this is due to the existence of preferential sites for atom emission in the presence of pre-existing defects, rather than thermal vacancy nucleation and migration. (author)

  1. Defect-Tolerant Monolayer Transition Metal Dichalcogenides

    DEFF Research Database (Denmark)

    Pandey, Mohnish; Rasmussen, Filip Anselm; Kuhar, Korina

    2016-01-01

    -principles investigation of defect tolerance in 29 monolayer transition metal dichalcogenides (TMDs) of interest for nanoscale optoelectronics. We find that the TMDs based on group VI and X metals form deep gap states upon creation of a chalcogen (S, Se, Te) vacancy, while the TMDs based on group IV metals form only...... shallow defect levels and are thus predicted to be defect-tolerant. Interestingly, all the defect sensitive TMDs have valence and conduction bands with a very similar orbital composition. This indicates a bonding/antibonding nature of the gap, which in turn suggests that dangling bonds will fall inside...

  2. Defect reduction through Lean methodology

    Science.gov (United States)

    Purdy, Kathleen; Kindt, Louis; Densmore, Jim; Benson, Craig; Zhou, Nancy; Leonard, John; Whiteside, Cynthia; Nolan, Robert; Shanks, David

    2010-09-01

    Lean manufacturing is a systematic method of identifying and eliminating waste. Use of Lean manufacturing techniques at the IBM photomask manufacturing facility has increased efficiency and productivity of the photomask process. Tools, such as, value stream mapping, 5S and structured problem solving are widely used today. In this paper we describe a step-by-step Lean technique used to systematically decrease defects resulting in reduced material costs, inspection costs and cycle time. The method used consists of an 8-step approach commonly referred to as the 8D problem solving process. This process allowed us to identify both prominent issues as well as more subtle problems requiring in depth investigation. The methodology used is flexible and can be applied to numerous situations. Advantages to Lean methodology are also discussed.

  3. Extended inflation with induced gravity

    International Nuclear Information System (INIS)

    Accetta, F.S.; Trester, J.J.; Department of Physics, Yale University, New Haven, Connecticut 06520)

    1989-01-01

    We consider a recently proposed extended model of inflation which improves upon the original old inflation scenario by achieving a graceful exit from the false-vacuum phase. In this paper extended inflation is generalized to include a potential V(phi) for the Brans-Dicke-type field phi. We find that whereas a graceful exit can still be had, the inclusion of a potential places constraints on the percolation time scale for exiting the inflationary phase. Additional constraints on V(phi) and the false-vacuum energy density rho /sub F/ from density and gravitational-wave perturbations are discussed. For initially small values of phi the false vacuum undergoes power-law inflation, while for initially large values of phi the expansion is exponential. Within true-vacuum regions slow-rolling inflation can occur. As a result, this model generically leads to multiple episodes of inflation. We discuss the significance these multiple episodes of inflation may have on the formation of large-scale structure and the production of voids

  4. Paternal occupation and birth defects: findings from the National Birth Defects Prevention Study.

    NARCIS (Netherlands)

    Desrosiers, T.A.; Herring, A.H.; Shapira, S.K.; Hooiveld, M.; Luben, T.J.; Herdt-Losavio, M.L.; Lin, S.; Olshan, A.F.

    2012-01-01

    Objectives: Several epidemiological studies have suggested that certain paternal occupations may be associated with an increased prevalence of birth defects in offspring. Using data from the National Birth Defects Prevention Study, the authors investigated the association between paternal occupation

  5. Defining defect specifications to optimize photomask production and requalification

    Science.gov (United States)

    Fiekowsky, Peter

    2006-10-01

    Reducing defect repairs and accelerating defect analysis is becoming more important as the total cost of defect repairs on advanced masks increases. Photomask defect specs based on printability, as measured on AIMS microscopes has been used for years, but the fundamental defect spec is still the defect size, as measured on the photomask, requiring the repair of many unprintable defects. ADAS, the Automated Defect Analysis System from AVI is now available in most advanced mask shops. It makes the use of pure printability specs, or "Optimal Defect Specs" practical. This software uses advanced algorithms to eliminate false defects caused by approximations in the inspection algorithm, classify each defect, simulate each defect and disposition each defect based on its printability and location. This paper defines "optimal defect specs", explains why they are now practical and economic, gives a method of determining them and provides accuracy data.

  6. Increasing reticle inspection efficiency and reducing wafer print-checks using automated defect classification and simulation

    Science.gov (United States)

    Ryu, Sung Jae; Lim, Sung Taek; Vacca, Anthony; Fiekowsky, Peter; Fiekowsky, Dan

    2013-09-01

    IC fabs inspect critical masks on a regular basis to ensure high wafer yields. These requalification inspections are costly for many reasons including the capital equipment, system maintenance, and labor costs. In addition, masks typically remain in the "requal" phase for extended, non-productive periods of time. The overall "requal" cycle time in which reticles remain non-productive is challenging to control. Shipping schedules can slip when wafer lots are put on hold until the master critical layer reticle is returned to production. Unfortunately, substituting backup critical layer reticles can significantly reduce an otherwise tightly controlled process window adversely affecting wafer yields. One major requal cycle time component is the disposition process of mask inspections containing hundreds of defects. Not only is precious non-productive time extended by reviewing hundreds of potentially yield-limiting detections, each additional classification increases the risk of manual review techniques accidentally passing real yield limiting defects. Even assuming all defects of interest are flagged by operators, how can any person's judgment be confident regarding lithographic impact of such defects? The time reticles spend away from scanners combined with potential yield loss due to lithographic uncertainty presents significant cycle time loss and increased production costs. Fortunately, a software program has been developed which automates defect classification with simulated printability measurement greatly reducing requal cycle time and improving overall disposition accuracy. This product, called ADAS (Auto Defect Analysis System), has been tested in both engineering and high-volume production environments with very successful results. In this paper, data is presented supporting significant reduction for costly wafer print checks, improved inspection area productivity, and minimized risk of misclassified yield limiting defects.

  7. An extension of fracture mechanics/technology to larger and smaller cracks/defects.

    Science.gov (United States)

    Abé, Hiroyuki

    2009-01-01

    Fracture mechanics/technology is a key science and technology for the design and integrity assessment of the engineering structures. However, the conventional fracture mechanics has mostly targeted a limited size of cracks/defects, say of from several hundred microns to several tens of centimeters. The author and his group has tried to extend that limited size and establish a new version of fracture technology for very large cracks used in geothermal energy extraction and for very small cracks/defects or damage often appearing in the combination of mechanical and electronic components of engineering structures. Those new versions are reviewed in this paper.

  8. An extension of fracture mechanics/technology to larger and smaller cracks/defects

    Science.gov (United States)

    Abé, Hiroyuki

    2009-01-01

    Fracture mechanics/technology is a key science and technology for the design and integrity assessment of the engineering structures. However, the conventional fracture mechanics has mostly targeted a limited size of cracks/defects, say of from several hundred microns to several tens of centimeters. The author and his group has tried to extend that limited size and establish a new version of fracture technology for very large cracks used in geothermal energy extraction and for very small cracks/defects or damage often appearing in the combination of mechanical and electronic components of engineering structures. Those new versions are reviewed in this paper. PMID:19907123

  9. Magnitude of Birth Defects in Central and Northwest Ethiopia from 2010-2014: A Descriptive Retrospective Study.

    Directory of Open Access Journals (Sweden)

    Molla Taye

    Full Text Available Birth defects are defined as structural and functional defects that develop during the organogenesis period and present at birth or detected later in life. They are one of the leading causes of infant and child mortality, morbidity, and long term disability. The magnitude of birth defects varies from country to country and from race/ethnicity to race/ethnicity, and about 40-60% of their causes are unknown. The known causes of birth defects are genetic and environmental factors which may be prevented. For various reasons, there is lack of data and research on birth defects in Ethiopia.The major objective of this study is to estimate the magnitude of birth defects in Ethiopia.A hospital based, retrospective, cross sectional, descriptive study was conducted. The subjects were babies/children aged 0-17years who visited selected hospitals between 2010 and 2014. Fourteen hospitals (8 in Addis Ababa, 6 in Amhara Region were selected purposively based on case load. A data retrieving form was developed to extract relevant information from record books.In the hospitals mentioned, 319,776 various medical records of children aged 0-17years were found. Of these, 6,076 (1.9% with 95% CI: 1.85%-1.95% children were diagnosed as having birth defects. The majority (58.5% of the children were male and 41.5% female. A slightly more than half (51.1% of the children were urban dwellers, while 48.9% were from rural areas. Among the participants of the study the proportion of birth defects ranged as follows: orofacial (34.2%, neural tube (30.8%, upper and lower limb (12.8%, cardiovascular system (10.3%, digestive system and abdominal wall (4.8%, unspecified congenital malformations (2.5%, Down syndrome (2%, genitourinary system (2%, head, face, and neck defects (0.4%, and others (0.3%. The trend of birth defects increased linearly over time [Extended Mantel-Haenszel chi square for linear trend = 356.7 (P<0.0001]. About 275 (4.5% of the cases had multiple (associated

  10. Classification and Methods of Shrinkage Defect Control

    Directory of Open Access Journals (Sweden)

    N. S. Larichev

    2016-01-01

    Full Text Available The objective is to put forward a proposal to divide the internal shrinkage defects into the dimensional levels according to defects of certain size and shape.The paper presents the terminology used to describe the internal shrinkage defects in the casting and shows its flaws. These include the lack of well-defined threshold size values and shape of defects. It is shown that in describing defects their sizes and shape are defined qualitatively rather than quantitatively. And it is noted that division of defects into pores and shells is based on the morphological characters.The paper notes that a distinct difference between defects is necessary because of different methods of their elimination from the casting body.The paper presents an overview of control methods to determine the defects of the shrinkage nature in castings. These are methods of destructive and non-destructive testing, such as Xrays, tomography, and metallography. The paper also shows advantages and disadvantages of the considered methods of control. Based on the control method capacities it offers to divide the shrinkage defects into the three dimensional levels.To estimate the shape of defects the paper suggests a new option, that is a shape criterion. By the example of the typical defects of each dimensional level are defined the threshold values of the shape criterion.The paper discusses the basic techniques to estimate the porosity and offers a relationship between the defects of different dimensional levels and a porosity score and percent. It shows that the transition from a dimensional level to another one is in line with not only increasing pore size, but also with a significant deterioration of the mechanical properties of castings.The main conclusions are as follows:1. At present, there is no single unambiguous classification of casting shrinkage defects in the technical literature.2. As follows from the analysis of the classifications of shrinkage defects, their

  11. EXTENDED REVERSE SURAL FLAP FOR LOWER LIMB COVERAGE

    Directory of Open Access Journals (Sweden)

    Biswajit Mishra

    2018-12-01

    Full Text Available BACKGROUND The reverse sural artery flap has been a workhorse for the reconstruction of distal third of leg, ankle, sole and foot. Major limitation of reverse sural flap has been venous congestion particularly when harvested from proximal third of the leg. Objective- To evaluate the efficacy, safety of the extended reverse sural flap from proximal third of the leg. MATERIALS AND METHODS A prospective study was conducted at the department of plastic surgery on twenty patients who needed soft tissue reconstruction in the distal third of the leg, ankle, heel, forefoot and midfoot due to various cause. In all cases flap was extended proximally to the upper third of the calf and neurovenoadipo fascial pedicled sural fasciocutaneous flap was harvested. RESULTS There were only two cases of marginal necrosis. None of the patients had complete necrosis. Two patients developed hypertrophy of the flap margin. CONCLUSION Distally based neuroveno adipofascial pedicled sural fasciocutaneous flap can be safely extended to proximal third of the leg and is a reliable option for reconstruction of the defects in the foot, ankle and sole.

  12. Modeling the relationships among internal defect features and external Appalachian hardwood log defect indicators

    Science.gov (United States)

    R. Edward. Thomas

    2009-01-01

    As a hardwood tree grows and develops, surface defects such as branch stubs and wounds are overgrown. Evidence of these defects remain on the log surface for decades and in many instances for the life of the tree. As the tree grows the defect is encapsulated or grown over by new wood. During this process the appearance of the defect in the tree's bark changes. The...

  13. Topics in Extended Dynamical Systems

    Science.gov (United States)

    Bhagavatula, Ravi S.

    This thesis consists of three chapters. Each chapter is self-contained and is devoted to the investigation of a particular topic in extended dynamical systems. In the first chapter, an approach based on Langevin equations is implemented to understand the non-Gaussian nature of the probability distribution function (PDF) of local diffusive variables in extended dynamical systems, e.g., a passive scalar advected by turbulent velocity fluctuations. Two mechanisms are proposed for the origin of non-Gaussian tails: One relies on the nature of temporal correlations of the fluctuations that couple additively to the diffusive field, leading to exponential and stretched exponential tails in the PDF; the other depends on multiplicative coupling between the diffusive field and the fluctuations, producing algebraic tails in the PDF. The mechanisms are illustrated using models for a passive scalar and also a current driven Josephson junction array. This study indicates that shapes of local PDFs in turbulent states are non-universal and crucially depend on local couplings and time scales. The second chapter establishes the existence of a class of locally conserving chaotic (deterministic) systems that exhibit Generic Scale Invariance--algebraic decay of spatial and temporal correlations without tuning parameters. This study also reveals the similarity between noise and chaos in extended systems as far as long-wavelength and long -time behavior is concerned. Specifically, a two dimensional coupled-map lattice model with a conserved density is numerically shown to exhibit, in agreement with heuristic arguments, algebraic decay of spatio-temporal correlations in chaotic states with simple predictable exponents. The third chapter investigates scaling behavior of earthquakes in seismic zone models in which an earthquake is modeled by a quasi-static description that ignores short -time dynamics during an earthquake. The models incorporate the essential feature of long-ranged stress

  14. Method and instrumentation for detection of rail defects, in particular rail top defects

    NARCIS (Netherlands)

    Li, Z.; Molodova, M.

    2011-01-01

    A method and instrumentation for detection of rail defects, in particular rail top defects, in a railway-track by measuring an axle box acceleration signal of a rail vehicle, wherein a longitudinal axle box acceleration signal is used as a measure to detect the occurrence of said rail defects, in

  15. Predicting internal white oak (Quercus alba) log defect features using surface defect indicator measurements

    Science.gov (United States)

    Ralph E. Thomas

    2012-01-01

    As hardwood trees grow and develop, surface defects such as limb stubs and wounds are overgrown and encapsulated into the tree. Evidence of these defects can remain on the tree's surface for decades and in many instances for the life of the tree. The location and severity of internal defects dictate the quality and value of products that can be obtained from logs...

  16. Extended uncertainty from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Costa Filho, Raimundo N., E-mail: rai@fisica.ufc.br [Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceará (Brazil); Braga, João P.M., E-mail: philipe@fisica.ufc.br [Instituto de Ciências Exatas e da Natureza-ICEN, Universidade da Integração Internacional da Lusofonia Afro-Brasileira-UNILAB, Campus dos Palmares, 62785-000 Acarape, Ceará (Brazil); Lira, Jorge H.S., E-mail: jorge.lira@mat.ufc.br [Departamento de Matemática, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceará (Brazil); Andrade, José S., E-mail: soares@fisica.ufc.br [Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceará (Brazil)

    2016-04-10

    A translation operator acting in a space with a diagonal metric is introduced to describe the motion of a particle in a quantum system. We show that the momentum operator and, as a consequence, the uncertainty relation now depend on the metric. It is also shown that, for any metric expanded up to second order, this formalism naturally leads to an extended uncertainty principle (EUP) with a minimum momentum dispersion. The Ehrenfest theorem is modified to include an additional term related to a tidal force arriving from the space curvature introduced by the metric. For one-dimensional systems, we show how to map a harmonic potential to an effective potential in Euclidean space using different metrics.

  17. Learning Extended Finite State Machines

    Science.gov (United States)

    Cassel, Sofia; Howar, Falk; Jonsson, Bengt; Steffen, Bernhard

    2014-01-01

    We present an active learning algorithm for inferring extended finite state machines (EFSM)s, combining data flow and control behavior. Key to our learning technique is a novel learning model based on so-called tree queries. The learning algorithm uses the tree queries to infer symbolic data constraints on parameters, e.g., sequence numbers, time stamps, identifiers, or even simple arithmetic. We describe sufficient conditions for the properties that the symbolic constraints provided by a tree query in general must have to be usable in our learning model. We have evaluated our algorithm in a black-box scenario, where tree queries are realized through (black-box) testing. Our case studies include connection establishment in TCP and a priority queue from the Java Class Library.

  18. Harmonic superspaces of extended supersymmetry

    International Nuclear Information System (INIS)

    Ivanov, E.; Kalitzin, S.; Nguyen Ai Viet; Ogievetsky, V.

    1984-01-01

    The main technical apparatus of the harmonic superspace approach to extended SUSY, the calculus of harmonic variables on homogeneous spaces of the SUSY automorphism groups, is presented in detail for N=2, 3, 4. The basic harmonics for the coset manifolds G/H with G=SU(2), H=U(1); G=SU(3), H=SU(2)xU(1) and H=U(1)xU(1); G=SU(4), H=SU(3)xU(1), H=SU(2)xSU(2)xU(1), H=SU(2)xU(1)xU(1) and H=U(1)xU(1)xU(1); G=USp(2), H=SU(2)xSU(2), H=SU(2)xU(1) and H=U(1)xU(1) are tabulated a number of useful relations among them

  19. Extended mission life support systems

    Science.gov (United States)

    Quattrone, P. D.

    1985-01-01

    Extended manned space missions which include interplanetary missions require regenerative life support systems. Manned mission life support considerations are placed in perspective and previous manned space life support system technology, activities and accomplishments in current supporting research and technology (SR&T) programs are reviewed. The life support subsystem/system technologies required for an enhanced duration orbiter (EDO) and a space operations center (SOC), regenerative life support functions and technology required for manned interplanetary flight vehicles, and future development requirements are outlined. The Space Shuttle Orbiters (space transportation system) is space cabin atmosphere is maintained at Earth ambient pressure of 14.7 psia (20% O2 and 80% N2). The early Shuttle flights will be seven-day flights, and the life support system flight hardware will still utilize expendables.

  20. Extended uncertainty from first principles

    International Nuclear Information System (INIS)

    Costa Filho, Raimundo N.; Braga, João P.M.; Lira, Jorge H.S.; Andrade, José S.

    2016-01-01

    A translation operator acting in a space with a diagonal metric is introduced to describe the motion of a particle in a quantum system. We show that the momentum operator and, as a consequence, the uncertainty relation now depend on the metric. It is also shown that, for any metric expanded up to second order, this formalism naturally leads to an extended uncertainty principle (EUP) with a minimum momentum dispersion. The Ehrenfest theorem is modified to include an additional term related to a tidal force arriving from the space curvature introduced by the metric. For one-dimensional systems, we show how to map a harmonic potential to an effective potential in Euclidean space using different metrics.

  1. Hamiltonian dynamics of extended objects

    International Nuclear Information System (INIS)

    Capovilla, R; Guven, J; Rojas, E

    2004-01-01

    We consider relativistic extended objects described by a reparametrization-invariant local action that depends on the extrinsic curvature of the worldvolume swept out by the object as it evolves. We provide a Hamiltonian formulation of the dynamics of such higher derivative models which is motivated by the ADM formulation of general relativity. The canonical momenta are identified by looking at boundary behaviour under small deformations of the action; the relationship between the momentum conjugate to the embedding functions and the conserved momentum density is established. The canonical Hamiltonian is constructed explicitly; the constraints on the phase space, both primary and secondary, are identified and the role they play in the theory is described. The multipliers implementing the primary constraints are identified in terms of the ADM lapse and shift variables and Hamilton's equations are shown to be consistent with the Euler-Lagrange equations

  2. Hamiltonian dynamics of extended objects

    Energy Technology Data Exchange (ETDEWEB)

    Capovilla, R [Departamento de FIsica, Centro de Investigacion y de Estudios Avanzados del IPN, Apdo Postal 14-740, 07000 Mexico, DF (Mexico); Guven, J [School of Theoretical Physics, Dublin Institute for Advanced Studies, 10 Burlington Road, Dublin 4 (Ireland); Rojas, E [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apdo Postal 70-543, 04510 Mexico, DF (Mexico)

    2004-12-07

    We consider relativistic extended objects described by a reparametrization-invariant local action that depends on the extrinsic curvature of the worldvolume swept out by the object as it evolves. We provide a Hamiltonian formulation of the dynamics of such higher derivative models which is motivated by the ADM formulation of general relativity. The canonical momenta are identified by looking at boundary behaviour under small deformations of the action; the relationship between the momentum conjugate to the embedding functions and the conserved momentum density is established. The canonical Hamiltonian is constructed explicitly; the constraints on the phase space, both primary and secondary, are identified and the role they play in the theory is described. The multipliers implementing the primary constraints are identified in terms of the ADM lapse and shift variables and Hamilton's equations are shown to be consistent with the Euler-Lagrange equations.

  3. Unexpected properties of the inductively coupled plasma induced defect in germanium

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, S.M.M., E-mail: sergio@up.ac.za; Auret, F.D.; Janse van Rensburg, P.J.; Nel, J.M.

    2014-04-15

    Inductively coupled plasma (ICP) etching of germanium introduces a single defect, the E{sub 0.31} electron trap, for a large range of argon partial pressures from 4×10{sup –3} to 6.5×10{sup –4} mbar that correspond to ion energies of 8 to 60 eV. Ge of three crystallographic orientations, (1 0 0), (1 1 0) and (1 1 1), treated with 20 and 60 eV ICP had defect concentration profiles that were similar in appearance, with a maximum concentration of 10{sup 14} cm{sup −3} extending more than a µm into the material, approximately three orders of magnitude deeper than what TRIM simulations predicted. All profiles were measured using Laplace deep level transient spectroscopy (L-DLTS), a technique that is sensitive to defect concentrations as low as 10{sup 11} cm{sup −3}. Isochronal annealing of samples showed concentration curves broadening after a 400 K anneal and decreasing to the 10{sup 13} cm{sup −3} level after a 450 K anneal. Unannealed samples measured after a year exhibited similar decreases in defect concentration without broadening of their profiles. A 550 K anneal lowered the defect concentration to levels below the L-DLTS detection limit. Thereafter additional plasma treatment of the surface failed to reintroduce this defect indicating that the structure required for the formation of E{sub 0.31} was no longer present in the region under observation.

  4. Formation of Defect-Free Latex Films on Porous Fiber Supports

    KAUST Repository

    Lively, Ryan P.

    2011-09-28

    We present here the creation of a defect-free polyvinylidene chloride barrier layer on the lumen-side of a hollow fiber sorbent. Hollow fiber sorbents have previously been shown to be promising materials for enabling low-cost CO 2 capture, provided a defect-free lumen-side barrier layer can be created. Film experiments examined the effect of drying rate, latex age, substrate porosity (porous vs nonporous), and substrate hydrophobicity/ hydrophilicity. Film studies show that in ideal conditions (i.e., slow drying, fresh latex, and smooth nonporous substrate), a defect-free film can be formed, whereas the other permutations of the variables investigated led to defective films. These results were extended to hollow fiber sorbents, and despite using fresh latex and relatively slow drying conditions, a defective lumen-side layer resulted. XRD and DSC indicate that polyvinylidene chloride latex develops crystallinity over time, thereby inhibiting proper film formation as confirmed by SEM and gas permeation. This and other key additional challenges associated with the porous hollow fiber substrate vs the nonporous flat substrate were overcome. By employing a toluene-vapor saturated drying gas (a swelling solvent for polyvinylidene chloride) a defect-free lumen-side barrier layer was created, as investigated by gas and water vapor permeation. © 2011 American Chemical Society.

  5. The Extended Virgo Cluster Catalog

    Science.gov (United States)

    Rey, Soo-Chang

    2015-08-01

    We present a new catalog of galaxies in the wider region of the Virgo cluster, based on the Sloan Digital Sky Survey (SDSS) Data Release 7. The Extended Virgo Cluster Catalog (EVCC) covers an area of 725 deg2 or 60.1 Mpc2. It is 5.2 times larger than the footprint of the classical Virgo Cluster Catalog (VCC) and reaches out to 3.5 times the virial radius of the Virgo cluster. We selected 1324 spectroscopically targeted galaxies with radial velocities less than 3000 km s-1. In addition, 265 galaxies that have been overlooked in the SDSS spectroscopic survey but have available redshifts in the NASA Extragalactic Database are also included. Our selection process secured a total of 1589 galaxies, 676 of which are not included in the VCC. The certain and possible cluster members are defined by means of redshift comparison with a cluster infall model. We employed two independent and complementary galaxy classification schemes: the traditional morphological classification based on the visual inspection of optical images and a characterization of galaxies from their spectroscopic features. SDSS u, g, r, i, and z passband photometry of all EVCC galaxies was performed using Source Extractor. We compare the EVCC galaxies with the VCC in terms of morphology, spatial distribution, and luminosity function. The EVCC defines a comprehensive galaxy sample covering a wider range in galaxy density that is significantly different from the inner region of the Virgo cluster. It will be the foundation for forthcoming galaxy evolution studies in the extended Virgo cluster region, complementing ongoing and planned Virgo cluster surveys at various wavelengths.

  6. Oral hydromorphone extended-release.

    Science.gov (United States)

    Guay, David R P

    2010-12-01

    To review the chemistry, pharmacodynamics, pharmacokinetics, efficacy, tolerability, dosing, and role of the Osmotic-controlled Release Oral delivery System (OROS) hydromorphone extended-release (ER) tablets. A MEDLINE/PUBMED search (1986-August 2010) was conducted to identify studies in the English language, with additional references being obtained from their bibliographies. All studies of hydromorphone ER were reviewed. This is the second long-acting hydromorphone formulation to receive approval by the Food and Drug Administration (a twice-daily formulation was approved in September 2004, but was subsequently withdrawn in July 2005). Hydromorphone is a semi-synthetic mu-opioid receptor agonist structurally similar to morphine, hydrocodone, and oxymorphone. OROS ER technology allows once-daily dosing. Clinical trials have focused on the convertibility of (an) other opioid(s) to hydromorphone ER in chronic malignant and nonmalignant pain. This product displays the expected opioid side effects, being comparable to oxycodone controlled-release. Coadministration with ethanol does not produce the degree of "dose-dumping" seen with the former hydromorphone twice-daily product or oxymorphone ER. Hydromorphone ER is indicated for the management of moderate-to-severe pain in opioidtolerant patients requiring continuous, around-the-clock opioid analgesia for an extended period of time. Dosage adjustment is recommended in patients with moderate hepatic impairment (Child-Pugh class B) and moderate renal impairment (creatinine clearance of 30-60 mL/min). Hydromorphone ER is the newest oral opioid to enter a crowded marketplace now totaling 15 different Schedule 2 opioids (including tapentadol), and tramadol, available in oral, parenteral, rectal, transdermal, transmucosal, and intranasal formulations. It does not appear to have any unique assets or liabilities and should be considered as one of many oral opioids available for the management of persistent pain of moderate

  7. THE EXTENDED VIRGO CLUSTER CATALOG

    International Nuclear Information System (INIS)

    Kim, Suk; Rey, Soo-Chang; Lee, Youngdae; Chung, Jiwon; Pak, Mina; Yi, Wonhyeong; Lee, Woong; Jerjen, Helmut; Lisker, Thorsten; Sung, Eon-Chang

    2014-01-01

    We present a new catalog of galaxies in the wider region of the Virgo cluster, based on the Sloan Digital Sky Survey (SDSS) Data Release 7. The Extended Virgo Cluster Catalog (EVCC) covers an area of 725 deg 2 or 60.1 Mpc 2 . It is 5.2 times larger than the footprint of the classical Virgo Cluster Catalog (VCC) and reaches out to 3.5 times the virial radius of the Virgo cluster. We selected 1324 spectroscopically targeted galaxies with radial velocities less than 3000 km s –1 . In addition, 265 galaxies that have been overlooked in the SDSS spectroscopic survey but have available redshifts in the NASA Extragalactic Database are also included. Our selection process secured a total of 1589 galaxies, 676 of which are not included in the VCC. The certain and possible cluster members are defined by means of redshift comparison with a cluster infall model. We employed two independent and complementary galaxy classification schemes: the traditional morphological classification based on the visual inspection of optical images and a characterization of galaxies from their spectroscopic features. SDSS u, g, r, i, and z passband photometry of all EVCC galaxies was performed using Source Extractor. We compare the EVCC galaxies with the VCC in terms of morphology, spatial distribution, and luminosity function. The EVCC defines a comprehensive galaxy sample covering a wider range in galaxy density that is significantly different from the inner region of the Virgo cluster. It will be the foundation for forthcoming galaxy evolution studies in the extended Virgo cluster region, complementing ongoing and planned Virgo cluster surveys at various wavelengths

  8. Extended Power Up-rates

    International Nuclear Information System (INIS)

    Jon Ball

    2006-01-01

    Full text of publication follows: Nuclear energy is a reliable and cost-competitive global source of power. With rising oil and gas prices, nuclear continues to provide economic and environmental benefits. Extended Power Up-rate (EPU) provides a means for existing nuclear assets to generate increased power and substantially reduce electrical generation costs. GE Energy's Nuclear Business is the global leader in boiling water reactor (BWR) technology. The experience-base of plants that have successfully achieved EPU includes Spain, Switzerland, Sweden, Germany and the United States. The GE experience-base includes fourteen BWRs with over fifty-eight reactor-years of operating experience at EPU conditions. Other than the expected plant modifications needed to accommodate higher steam flows, flow-induced vibration (FIV) has been identified as the major area of concern when up-rating. Two plants have experienced damage to their steam dryers that has lead to an extensive program to improve the understanding of the effects of up-rates. This program includes extensive in-plant data collection, the development of a scale model test facility to study components susceptible to FIV and improvements in analytical techniques for evaluating loading on reactor internals. As global energy demands increase, oil and gas prices escalate, and environmental concerns over greenhouse effects challenge us to find environmentally friendly sources of energy, Nuclear is the most viable and economical source of power in the world. With a focused effort on plant reliability, existing plants can undergo Extended Power Up-rate, and continue to meet the ever-increasing energy demands in the world. (author)

  9. THE EXTENDED VIRGO CLUSTER CATALOG

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Suk; Rey, Soo-Chang; Lee, Youngdae; Chung, Jiwon; Pak, Mina; Yi, Wonhyeong; Lee, Woong [Department of Astronomy and Space Science, Chungnam National University, 99 Daehak-ro, Daejeon 305-764 (Korea, Republic of); Jerjen, Helmut [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston, ACT 2611 (Australia); Lisker, Thorsten [Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg (ZAH), Mönchhofstraße 12-14, D-69120 Heidelberg (Germany); Sung, Eon-Chang [Korea Astronomy and Space Science institute, 776 Daedeokdae-ro, Daejeon 305-348 (Korea, Republic of)

    2015-01-01

    We present a new catalog of galaxies in the wider region of the Virgo cluster, based on the Sloan Digital Sky Survey (SDSS) Data Release 7. The Extended Virgo Cluster Catalog (EVCC) covers an area of 725 deg{sup 2} or 60.1 Mpc{sup 2}. It is 5.2 times larger than the footprint of the classical Virgo Cluster Catalog (VCC) and reaches out to 3.5 times the virial radius of the Virgo cluster. We selected 1324 spectroscopically targeted galaxies with radial velocities less than 3000 km s{sup –1}. In addition, 265 galaxies that have been overlooked in the SDSS spectroscopic survey but have available redshifts in the NASA Extragalactic Database are also included. Our selection process secured a total of 1589 galaxies, 676 of which are not included in the VCC. The certain and possible cluster members are defined by means of redshift comparison with a cluster infall model. We employed two independent and complementary galaxy classification schemes: the traditional morphological classification based on the visual inspection of optical images and a characterization of galaxies from their spectroscopic features. SDSS u, g, r, i, and z passband photometry of all EVCC galaxies was performed using Source Extractor. We compare the EVCC galaxies with the VCC in terms of morphology, spatial distribution, and luminosity function. The EVCC defines a comprehensive galaxy sample covering a wider range in galaxy density that is significantly different from the inner region of the Virgo cluster. It will be the foundation for forthcoming galaxy evolution studies in the extended Virgo cluster region, complementing ongoing and planned Virgo cluster surveys at various wavelengths.

  10. 49 CFR 213.337 - Defective rails.

    Science.gov (United States)

    2010-10-01

    ..., due to incomplete penetration of the weld metal between the rail ends, lack of fusion between weld and... cracking. Weld defects may originate in the rail head, web, or base, and in some cases, cracks may progress... 49 Transportation 4 2010-10-01 2010-10-01 false Defective rails. 213.337 Section 213.337...

  11. 7 CFR 52.3761 - Defects.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Defects. 52.3761 Section 52.3761 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... to olives pitted along an axis other than the stem-flower axis. A defect is a unit where the angle of...

  12. 16 CFR 1115.4 - Defect.

    Science.gov (United States)

    2010-01-01

    ... defect exists. At a minimum, defect includes the dictionary or commonly accepted meaning of the word... appliance presents a shock hazard because, through a manufacturing error, its casing can be electrically... for home garages is advertised as activating when carbon monoxide fumes reach a dangerous level but...

  13. Birth defects in children with newborn encephalopathy

    NARCIS (Netherlands)

    Felix, JF; Badawi, N; Kurinczuk, JJ; Bower, C; Keogh, JM; Pemberton, PJ

    2000-01-01

    This study was designed to investigate birth defects found in association with newborn encephalopathy. All possible birth defects were ascertained in a population-based study of 276 term infants with moderate or severe encephalopathy and 564 unmatched term control infants. A strong association

  14. Simple intrinsic defects in InAs :

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, Peter Andrew

    2013-03-01

    This Report presents numerical tables summarizing properties of intrinsic defects in indium arsenide, InAs, as computed by density functional theory using semi-local density functionals, intended for use as reference tables for a defect physics package in device models.

  15. Encephalocele and associated skull defects | Komolafe | West ...

    African Journals Online (AJOL)

    Encephalocele is a common congenital problem in the practice of Neurosurgery worldwide, with varying sizes of the underlying skull defects. This study was carried out to determine the size of the problem; to assess whether the skull defects are being under-managed or not; and also to determine those patients that will ...

  16. Unsound defect volume in hardwood pallet cants

    Science.gov (United States)

    Philip Araman; Matt Winn; Firoz Kabir; Xavier Torcheux; Guillaume Loizeaud

    2003-01-01

    A study was conducted to determine the percentage of unsound defect volume to sound/clear wood in pallet cants at selected sawmills in Virginia and West Virginia. Splits,wane, shake, holes, decay, unsound knots, bark pockets, and mechanical defects were all considered to be unsound. Data were collected from seven Appalachian area sawmills for four hardwood species: red...

  17. Interventricular communication in complete atrioventricular septal defect

    NARCIS (Netherlands)

    Suzuki, K.; Ho, S. Y.; Anderson, R. H.; Becker, A. E.; Neches, W. H.; Tatsuno, K.; Mimori, S.

    1998-01-01

    Little attention has been paid to whether the interventricular communication in complete atrioventricular septal defect is different beneath the superior and inferior bridging leaflets, a feature of obvious surgical significance. We searched for a defect under the bridging leaflets and examined the

  18. 9 CFR 91.30 - Defective fittings.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Defective fittings. 91.30 Section 91... LIVESTOCK FOR EXPORTATION Inspection of Vessels and Accommodations § 91.30 Defective fittings. If previously used fittings aboard an ocean vessel are employed, any portion thereof found by the inspector to be...

  19. Failures and Defects in the Building Process

    DEFF Research Database (Denmark)

    Jørgensen, Kirsten

    2009-01-01

    Function failures, defects, mistakes and poor communication are major problems for the construction sector. As the empirical element in the research, a large construction site was observed from the very start to the very end and all failures and defects of a certain size were recorded and analysed...

  20. Indicators for Building Process without Final Defects -

    DEFF Research Database (Denmark)

    Jørgensen, Kirsten; Rasmussen, Grane Mikael Gregaard; Thuesen, Christian Langhoff

    2011-01-01

    This article introduces the preliminary data analysis, as well as the underlying theories and methods for identifying the indicators for building process without final defects. Since 2004, the Benchmark Centre for the Danish Construction Sector (BEC) has collected information about legal defects...

  1. Defective Reduction in Frozen Pie Manufacturing Process

    Science.gov (United States)

    Nooted, Oranuch; Tangjitsitcharoen, Somkiat

    2017-06-01

    The frozen pie production has a lot of defects resulting in high production cost. Failure mode and effect analysis (FMEA) technique has been applied to improve the frozen pie process. Pareto chart is also used to determine the major defects of frozen pie. There are 3 main processes that cause the defects which are the 1st freezing to glazing process, the forming process, and the folding process. The Risk Priority Number (RPN) obtained from FMEA is analyzed to reduce the defects. If RPN of each cause exceeds 45, the process will be considered to be improved and selected for the corrective and preventive actions. The results showed that RPN values decreased after the correction. Therefore, the implementation of FMEA technique can help to improve the performance of frozen pie process and reduce the defects approximately 51.9%.

  2. Tritium releases, birth defects and infant deaths

    International Nuclear Information System (INIS)

    1991-01-01

    The AECB has published a report 'Tritium releases from the Pickering Nuclear Generating Station and Birth Defects and Infant Mortality in Nearby Communities 1971-1988' (report number INFO-0401). This presents the results of a detailed analysis of deaths and birth defects occurring in infants born to mothers living in the area (25 Km radius) of the Pickering nuclear power plant, over an 18-year period. The analysis looked at the frequency of these defects and deaths in comparison to the general rate for Ontario, and also in relation to airborne and waterborne releases of tritium from the power plant. The overall conclusion was that the rates of infant death and birth defects were generally not higher in the study population than in all of Ontario. There was no prevalent relationship between these deaths and defects and tritium releases measured either at the power plant or by ground monitoring stations t some distance from the facility

  3. [Skin defect coverage with micro skin graft].

    Science.gov (United States)

    Gümüş, Nazim; Kaya, Yalçin; Karakaya, Sadik; Camci, Cemalettin

    2002-04-01

    The aim of this study is to coverage of the large skin defect with microskin graft. The wound coverage of the large skin defect may be difficult with auto skin graft. In these patients, split thickness skin graft may be used in a bloc shape or expanded skin graft shape and a stamp skin graft shape or expanded stamp skin graft shape. On the other hand, split thickness skin graft may be used as a micrograft shape after the mincing process, which reduces of the graft size in a few millimeters. In this study, 6 patients with skin defect was admitted in our clinic, and their skin defect was treated with micro skin graft. Expansion ratio was 1:15. Epithelialization on the wound surface was completed in 4 to 6 weeks and cobblestone appearance was observed after the wound coverage. Skin defect coverage with micrograft is an effective technique like the other skin graft coverage methods.

  4. Defect rates in butt welded steel pipes

    International Nuclear Information System (INIS)

    Guille-Stevens, D.; Silcock, P.

    1980-01-01

    As the primary circuit of CANDU reactors consists largely of pipe, the reliability of pipe welds is of interest to reactor designers. A project involving 64 000 manual and semi-automatic pipe welds was inspected to the requirements of ANSI B31.3. Records of 6 000 carbon steel and 1 900 alloy steel butt welds ranging from 50 to 400 mm were inspected by radiography and ultrasonics, and analysed. No correlation between defects and number of weld passes was observed. However, small pipes exhibited a higher defect rate, per weld length and per weld volume, than did large pipes. Porosity was the major cause of defects (60 per cent) followed by root defects (27 per cent); only one crack was recorded. The results show that small (50 mm) pipe welds have the highest defect rate; however, the low overall rate shows that high standards can be maintained over many thousand welds [af

  5. Stafne Bone Defect: Report of Two Cases

    Directory of Open Access Journals (Sweden)

    A. P. Münevveroğlu

    2012-01-01

    Full Text Available Stafne bone defects are asymptomatic lingual bone depressions of the lower jaw. In 1942, Stafne described for the first time 35 asymptomatic, radiolucent cavities, unilaterally located in the posterior region of the mandible, between the mandibular angle and the third molar, below the inferior dental canal and slightly above the basis mandibulae. In this study, the clinical and radiological characteristics of 2 cases of Stafne bone defects were described. Orthopantomograph and CBCT were used for diagnosing the defects. The bone defects of two patients in this study were asymptomatic and any other bone lesions, such as cysts and tumors, were excluded because no signs of inflammatory or tumoral changes were evident Therefore, surgery was not considered and the patients were followed for 1 year. Stafne bone defect was an incidental finding, presenting no evolutionary changes, and as such conservatory therapy based on periodic controls was indicated. Currently, complementary techniques such as CT are sufficient to establish a certain diagnosis.

  6. Topological defect dynamics in operando battery nanoparticles

    Science.gov (United States)

    Ulvestad, Andrew; Meng, Shirley; Shpyrko, Oleg

    2015-03-01

    Topological defects are ubiquitous in physics and manifest themselves as magnetic monopoles in quantum field theories and crystallographic imperfections in condensed matter systems. In the latter, the defect properties determine many of the material's properties and as such represent substantial novel opportunities for design and optimization of desired functionalities through deliberate defect engineering and manipulation. However, this approach of ``defect choreography'' currently suffers from the lack of suitable nanoscale probes to track buried single defects in-situ and in-operando. Here we report 3D imaging of single edge dislocations and their motion in an individual nanoparticle under operando conditions in a Lithium ion battery. We further observe the dislocation act as a nucleation point during the structural phase transformation. We find that the region near the dislocation enters a negative Poisson's ratio, or auxetic, regime at high voltage. Dislocation imaging is thus a powerful nanotechnology and it opens a new, powerful avenue for facilitating improvement of nanostructured devices.

  7. Radioactive preparation of defects in solids

    International Nuclear Information System (INIS)

    Lambe, J.

    1962-01-01

    One of the major areas of interest in solid state physics is the study of defects in nearly perfect crystals. The controlled formation of such defects is thus an important aspect of these studies. Chemical additions and radiation damage are among the techniques which have been widely used to make such defects. In the present work some possibilities have been examined of using radioactive decay to form defects in solids. The technique is simply to make as perfect a material as possible but with some of the host crystal atoms radioactive. When these atoms decay the daughter product essentially forms the defect. As a simple means of testing the feasibility of this technique, it was used to prepare tritium atoms trapped in a crystal of solid molecular tritium. The experiments indicate that the technique is feasible and should have particular application to the preparation of free radicals in organic materials which are fairly resistant to radiation damage. (author) [fr

  8. Imaging Findings of Pelvic Tumor Thrombosis Extending from Sacral Bone Metastasis of Adrenocortical Carcinoma

    Directory of Open Access Journals (Sweden)

    Kenichiro Ishida

    2012-01-01

    Full Text Available We report the imaging findings of a patient with adrenocortical carcinoma who showed pelvic tumor thrombosis extending from sacral bone metastasis. Contrast-enhanced computed tomography demonstrated extensive intraluminal filling defects in the pelvic veins. A lytic lesion in the sacrum was also noted and continuity between the sacral lesion and the filling defect in the branch of pelvic veins was indicated. The filling defects showed increased uptake on positron emission tomography with 18F-fluorodeoxyglucose and single-photon emission computed tomography with 131I-iodomethylnorcholesterol, and fusion images with computed tomography aided the localization of the increased uptake areas. Multimodality imaging may be beneficial for the characterization and localization of lesions in patients suspected of having metastatic adrenocortical carcinoma.

  9. Many-Body Theory of Proton-Generated Point Defects for Losses of Electron Energy and Photons in Quantum Wells

    Science.gov (United States)

    Huang, Danhong; Iurov, Andrii; Gao, Fei; Gumbs, Godfrey; Cardimona, D. A.

    2018-02-01

    The effects of point defects on the loss of either energies of ballistic electron beams or incident photons are studied by using a many-body theory in a multi-quantum-well system. This theory includes the defect-induced vertex correction to a bare polarization function of electrons within the ladder approximation, and the intralayer and interlayer screening of defect-electron interactions is also taken into account in the random-phase approximation. The numerical results of defect effects on both energy-loss and optical-absorption spectra are presented and analyzed for various defect densities, numbers of quantum wells, and wave vectors. The diffusion-reaction equation is employed for calculating distributions of point defects in a layered structure. For completeness, the production rate for Frenkel-pair defects and their initial concentration are obtained based on atomic-level molecular-dynamics simulations. By combining the defect-effect, diffusion-reaction, and molecular-dynamics models with an available space-weather-forecast model, it will be possible in the future to enable specific designing for electronic and optoelectronic quantum devices that will be operated in space with radiation-hardening protection and, therefore, effectively extend the lifetime of these satellite onboard electronic and optoelectronic devices. Specifically, this theory can lead to a better characterization of quantum-well photodetectors not only for high quantum efficiency and low dark current density but also for radiation tolerance or mitigating the effects of the radiation.

  10. Thyroid gland development and defects.

    Science.gov (United States)

    Kratzsch, Juergen; Pulzer, Ferdinand

    2008-02-01

    During the functional ontogenesis of the thyroid gland an increasing number of transcription factors play fundamental roles in thyroid-cell differentiation, maintenance of the differentiated state, and thyroid-cell proliferation. The early growth and development of the fetal thyroid appears to be generally independent of thyroid-stimulating hormone (TSH). TSH and thyroxine (T4) levels increase from the 12th week of gestation until delivery, whereas triiodothyronine (T3) levels remain relatively low. At birth, a cold-stimulated short-lived TSH surge is observed, followed by a TSH decrease until day 3 or 4 of life by T4 feedback inhibition. Disorders of thyroid gland development and/or function are relatively common, affecting approximately one newborn infant in 2000-4000. The most prevalent disease, congenital hypothyroidism, is frequently caused by genetic defects of transcription factors involved in the development of the thyroid or pituitary gland. A major cause of congenital hyperthyroidism is the transplacental passage of stimulating thyrotropin antibodies from the mother to the fetus. Hypothyroxinaemia or hypotriiodthyroninaemia is frequently observed in preterm infants with or without severe non-thyroidal illness. Whereas congenital hypo- and hyperthyroidism may be treated successfully with T4 or thyrostatic drugs, there is still insufficient evidence on whether the use of T4 for treatment of the latter condition results in changes in neonatal morbidity or reductions in neurodevelopmental impairment.

  11. Characterization of the structure and chemistry of defects in materials

    International Nuclear Information System (INIS)

    Larson, B.C.; Ruehle, M.; Seidman, D.N.

    1988-01-01

    Research programs, presented at the materials research symposium, on defects in materials are presented. Major areas include: point defects, defect aggregates, and ordering; defects in non-metals and semiconductors; atomic resolution imaging of defects; and gain boundaries, interfaces, and layered materials. Individual projects are processed separately for the data bases

  12. Distribution of defects in wind turbine blades and reliability assessment of blades containing defects

    DEFF Research Database (Denmark)

    Stensgaard Toft, Henrik; Branner, Kim; Berring, Peter

    2009-01-01

    on the assumption that one error in the production process tends to trigger several defects. For both models additional information about number, type and size of the defects is included as stochastic variables. The probability of failure for a wind turbine blade will not only depend on variations in the material......In the present paper two stochastic models for the distribution of defects in wind turbine blades are proposed. The first model assumes that the individual defects are completely randomly distributed in the blade. The second model assumes that the defects occur in clusters of different size based...... properties and the load but also on potential defects in the blades. As a numerical example the probability of failure is calculated for the main spar both with and without defects in terms of delaminations. The delaminations increase the probability of failure compared to a perfect blade, but by applying...

  13. [Extending preimplantation genetic diagnosis to HLA typing: the Paris experience].

    Science.gov (United States)

    Steffann, J; Frydman, N; Burlet, P; Gigarel, N; Feyereisen, E; Kerbrat, V; Tachdjian, G; Munnich, A; Frydman, R

    2005-10-01

    Preimplantation genetic diagnosis (PGD) consists in the genetic analysis of one or two cells. These cells (blastomeres) are sampled from embryos, obtained by in vitro fertilization, at the third day of development. Since 1998, the bioethical laws (1994) and their decrees restricted PGD practices in France, strictly to the avoidance of the birth of a child affected with a genetic defect. In parallel, works on blood cord transplantation, taken at the birth of a compatible HLA sibling, showed very encouraging results, particularly for the treatment of Fanconi anemia. In 2001, Verlinsky et al., have reported the first PGD for Fanconi anaemia combined with HLA typing, allowing the birth of a healthy child, HLA-identical with his affected sister. The "designer baby" concept was born. The French law, which allowed PGD under specific conditions, i.e. when the genetic defect has been characterized in one parent at least, recently extended PGD to HLA typing when embryos are at risk of a genetic disorder. Article L.2131-4-1 (August 2004) allows the practice of HLA typing for PGD embryos when an elder sibling is affected with a genetic disorder and need stem cell transplantation. The HLA-matched offspring resulting from PGD can give cord blood at birth to supply the necessary therapy. This double selection give rise to serious ethical problems, but technical difficulties and legal restrictions will probably limit the development of such a procedure.

  14. A quantum extended Kalman filter

    International Nuclear Information System (INIS)

    Emzir, Muhammad F; Woolley, Matthew J; Petersen, Ian R

    2017-01-01

    In quantum physics, a stochastic master equation (SME) estimates the state (density operator) of a quantum system in the Schrödinger picture based on a record of measurements made on the system. In the Heisenberg picture, the SME is a quantum filter. For a linear quantum system subject to linear measurements and Gaussian noise, the dynamics may be described by quantum stochastic differential equations (QSDEs), also known as quantum Langevin equations, and the quantum filter reduces to a so-called quantum Kalman filter. In this article, we introduce a quantum extended Kalman filter (quantum EKF), which applies a commutative approximation and a time-varying linearization to systems of nonlinear QSDEs. We will show that there are conditions under which a filter similar to a classical EKF can be implemented for quantum systems. The boundedness of estimation errors and the filtering problem with ‘state-dependent’ covariances for process and measurement noises are also discussed. We demonstrate the effectiveness of the quantum EKF by applying it to systems that involve multiple modes, nonlinear Hamiltonians, and simultaneous jump-diffusive measurements. (paper)

  15. The Extended Mission Rover (EMR)

    Science.gov (United States)

    Shields, W.; Halecki, Anthony; Chung, Manh; Clarke, Ken; Frankle, Kevin; Kassemkhani, Fariba; Kuhlhoff, John; Lenzini, Josh; Lobdell, David; Morgan, Sam

    A key component in ensuring America's status as a leader in the global community is its active pursuit of space exploration. On the twentieth anniversary of Apollo 11, President George Bush challenged the nation to place a man on the moon permanently and to conduct human exploration of Mars in the 21st century. The students of the FAMU/FSU College of Engineering hope to make a significant contribution to this challenge, America's Space Exploration Initiative (SEI), with their participation in the NASA/USRA Advanced Design Program. The project selected by the 1991/1992 Aerospace Design group is the design of an Extended Mission Rover (EMR) for use on the lunar surface. This vehicle will serve as a mobile base to provide future astronauts with a 'shirt-sleeve' living and working environment. Some of the proposed missions are planetary surface exploration, construction and maintenance, hardware setup, and in situ resource experimentation. This vehicle will be put into use in the 2010-2030 time frame.

  16. Extended attention span training system

    Science.gov (United States)

    Pope, Alan T.; Bogart, Edward H.

    1991-01-01

    Attention Deficit Disorder (ADD) is a behavioral disorder characterized by the inability to sustain attention long enough to perform activities such as schoolwork or organized play. Treatments for this disorder include medication and brainwave biofeedback training. Brainwave biofeedback training systems feed back information to the trainee showing him how well he is producing the brainwave pattern that indicates attention. The Extended Attention Span Training (EAST) system takes the concept a step further by making a video game more difficult as the player's brainwaves indicate that attention is waning. The trainee can succeed at the game only by maintaining an adequate level of attention. The EAST system is a modification of a biocybernetic system that is currently being used to assess the extent to which automated flight management systems maintain pilot engagement. This biocybernetic system is a product of a program aimed at developing methods to evaluate automated flight deck designs for compatibility with human capabilities. The EAST technology can make a contribution in the fields of medical neuropsychology and neurology, where the emphasis is on cautious, conservative treatment of youngsters with attention disorders.

  17. Increasing reticle inspection efficiency and reducing wafer printchecks at 14nm using automated defect classification and simulation

    Science.gov (United States)

    Paracha, Shazad; Goodman, Eliot; Eynon, Benjamin G.; Noyes, Ben F.; Ha, Steven; Kim, Jong-Min; Lee, Dong-Seok; Lee, Dong-Heok; Cho, Sang-Soo; Ham, Young M.; Vacca, Anthony D.; Fiekowsky, Peter J.; Fiekowsky, Daniel I.

    2014-10-01

    IC fabs inspect critical masks on a regular basis to ensure high wafer yields. These requalification inspections are costly for many reasons including the capital equipment, system maintenance, and labor costs. In addition, masks typically remain in the "requal" phase for extended, non-productive periods of time. The overall "requal" cycle time in which reticles remain non-productive is challenging to control. Shipping schedules can slip when wafer lots are put on hold until the master critical layer reticle is returned to production. Unfortunately, substituting backup critical layer reticles can significantly reduce an otherwise tightly controlled process window adversely affecting wafer yields. One major requal cycle time component is the disposition process of mask inspections containing hundreds of defects. Not only is precious non-productive time extended by reviewing hundreds of potentially yield-limiting detections, each additional classification increases the risk of manual review techniques accidentally passing real yield limiting defects. Even assuming all defects of interest are flagged by operators, how can any person's judgment be confident regarding lithographic impact of such defects? The time reticles spend away from scanners combined with potential yield loss due to lithographic uncertainty presents significant cycle time loss and increased production costs An automatic defect analysis system (ADAS), which has been in fab production for numerous years, has been improved to handle the new challenges of 14nm node automate reticle defect classification by simulating each defect's printability under the intended illumination conditions. In this study, we have created programmed defects on a production 14nm node critical-layer reticle. These defects have been analyzed with lithographic simulation software and compared to the results of both AIMS optical simulation and to actual wafer prints.

  18. Fermionic currents flowing along extended objects

    OpenAIRE

    Ringeval, Christophe

    2002-01-01

    This PhD thesis discusses the internal structure of topological defects, and branes in extra-dimensions, carrying fermionic currents. The general framework in which these objects may appear is presented in the first part while the second part is devoted to the dynamic of cosmic strings, a class of topological defects of uttermost importance to modern cosmology, as it can be obtained from a macroscopic covariant formalism. This formalism offers a unified description of cosmic strings, includin...

  19. Exploring atomic defects in molybdenum disulphide monolayers

    KAUST Repository

    Hong, Jinhua

    2015-02-19

    Defects usually play an important role in tailoring various properties of two-dimensional materials. Defects in two-dimensional monolayer molybdenum disulphide may be responsible for large variation of electric and optical properties. Here we present a comprehensive joint experiment-theory investigation of point defects in monolayer molybdenum disulphide prepared by mechanical exfoliation, physical and chemical vapour deposition. Defect species are systematically identified and their concentrations determined by aberration-corrected scanning transmission electron microscopy, and also studied by ab-initio calculation. Defect density up to 3.5 × 10 13 cm \\'2 is found and the dominant category of defects changes from sulphur vacancy in mechanical exfoliation and chemical vapour deposition samples to molybdenum antisite in physical vapour deposition samples. Influence of defects on electronic structure and charge-carrier mobility are predicted by calculation and observed by electric transport measurement. In light of these results, the growth of ultra-high-quality monolayer molybdenum disulphide appears a primary task for the community pursuing high-performance electronic devices.

  20. Modified Whale's tail technique for the management of bone-defect in anterior teeth.

    Science.gov (United States)

    Kuriakose, Anu; Ambooken, Majo; Jacob, Jayan; John, Priya

    2015-01-01

    The purpose of this case report is to describe the efficacy of a modified Whale's tail technique to achieve primary closure and thereby aid in regeneration of an interdental osseous defect between maxillary central incisors complicated by an aberrant frenal attachment. A healthy 32-year-old female patient reported with the complaint of spacing between her upper front teeth. Clinical examination revealed an aberrant frenum extending into the interdental papilla in relation to the central incisors. There was a 6 mm periodontal pocket in relation to the mesiopalatal aspect of maxillary left central incisor. Intraoral periapical radiograph showed vertical bone loss in relation to mesial aspect of maxillary left central incisor. A modified Whale's tail flap was employed to access the area. The defect was filled with an alloplastic graft. Six months postoperative review showed complete elimination of the pocket along with radiographic bone fill of the defect.

  1. Incorporation of defects into the central atoms model of a metallic glass

    International Nuclear Information System (INIS)

    Lass, Eric A.; Zhu Aiwu; Shiflet, G.J.; Joseph Poon, S.

    2011-01-01

    The central atoms model (CAM) of a metallic glass is extended to incorporate thermodynamically stable defects, similar to vacancies in a crystalline solid, within the amorphous structure. A bond deficiency (BD), which is the proposed defect present in all metallic glasses, is introduced into the CAM equations. Like vacancies in a crystalline solid, BDs are thermodynamically stable entities because of the increase in entropy associated with their creation, and there is an equilibrium concentration present in the glassy phase. When applied to Cu-Zr and Ni-Zr binary metallic glasses, the concentration of thermally induced BDs surrounding Zr atoms reaches a relatively constant value at the glass transition temperature, regardless of composition within a given glass system. Using this 'critical' defect concentration, the predicted temperatures at which the glass transition is expected to occur are in good agreement with the experimentally determined glass transition temperatures for both alloy systems.

  2. Study of irradiation induced defects in silicon

    International Nuclear Information System (INIS)

    Pal, Gayatri; Sebastian, K.C.; Somayajulu, D.R.S.; Chintalapudi, S.N.

    2000-01-01

    Pure high resistivity (6000 ohm-cm) silicon wafers were recoil implanted with 1.8 MeV 111 In ions. As-irradiated wafers showed a 13 MHz quadrupole interaction frequency, which was not observed earlier. The annealing behaviour of these defects in the implanted wafers was studied between room temperature and 1073 K. At different annealing temperatures two more interaction frequencies corresponding to defect complexes D2 and D3 are observed. Even though the experimental conditions were different, these are identical to the earlier reported ones. Based on an empirical point charge model calculation, an attempt is made to identify the configuration of these defect complexes. (author)

  3. Mass defect effects in atomic clocks

    Science.gov (United States)

    Yudin, Valeriy; Taichenachev, Alexey

    2018-03-01

    We consider some implications of the mass defect on the frequency of atomic transitions. We have found that some well-known frequency shifts (the gravitational shift and motion-induced shifts such as quadratic Doppler and micromotion shifts) can be interpreted as consequences of the mass defect in quantum atomic physics, i.e. without the need for the concept of time dilation used in special and general relativity theories. Moreover, we show that the inclusion of the mass defect leads to previously unknown shifts for clocks based on trapped ions.

  4. Interdisciplinary Management of an Isolated Intrabony Defect

    Directory of Open Access Journals (Sweden)

    Sheetal Ghivari

    2014-01-01

    Full Text Available The treatment of intrabony defects is a real challenge in molar teeth as it is chronic, slowly progressing disease which needs timely intervention. Periodontal inflammation associated with intrabony defect is not a separate entity as it secondarily affects the pulp causing retrograde pulpitis. However, treatment of these lesions will be complicated due to extensive bone loss. The tooth was endodontically treated followed by periodontal surgery to eliminate the deep periodontal pocket and promote bone fill in osseous defect. PepGen P-15 composited with platelet rich plasma was utilized for enhancing bone formation. The combination of these graft materials provides synergistic effect on bone regeneration.

  5. Stress concentrations in nanoscale defective graphene

    Science.gov (United States)

    Wang, Congwei; Wang, Junzhong; Barber, Asa H.

    2017-11-01

    Defect-free graphene nanosheets are the strongest material known but manufactured graphene tends to contain flaws of different forms and dimensions, leading to the degradation of mechanical performance. Here we report a quantitative mechanical approach to quantitatively evaluate the influence of defects within exfoliated pristine graphene sheets. Results indicate stress concentrations around defects within graphene sheets that lower strength. The description of stress concentration broadly follows a Griffith strength approach for continuum materials, despite the non-continuum structure of graphene, but has little impact on the Young's modulus.

  6. Tibial and fibular developmental fields defects

    International Nuclear Information System (INIS)

    Khoury, N.J.; Haddad, M.C.; Hourani, M.H.

    1999-01-01

    Malformations of the lower limbs are rare and heterogeneous anomalies. To explain the diversity and complexity of these abnormalities, authors introduced the concept of tibial and fibular developmental fields. Defects in these fields are responsible for different malformations, which have been described, to our knowledge, in only one report in the radiology literature. We present a case of a newborn with femoral bifurcation, absent fibulae and talar bones, ankle and foot malformations, and associated atrial septal defect. Our case is an example of defects in both fibular and tibial developmental fields. (orig.)

  7. Radiation defects in complex perovskite solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kuklja, M.M., E-mail: mkukla@nsf.gov [Materials Science and Engineering Dept., University of Maryland, College Park (United States); Kotomin, E.A. [Institute for Solid State Physics, University of Latvia, Riga (Latvia); Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Sharia, O. [Materials Science and Engineering Dept., University of Maryland, College Park (United States); Mastrikov, Yu.A. [Materials Science and Engineering Dept., University of Maryland, College Park (United States); Institute for Solid State Physics, University of Latvia, Riga (Latvia); Maier, J. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany)

    2014-05-01

    First principles density functional theory (DFT) based modeling is performed to explore formation energies of a series of point cation and oxygen defects, Frenkel and Schottky disorder, as well as structural disorder in Ba{sub 1−x}Sr{sub x}Co{sub 1−y}Fe{sub y}O{sub 3−δ} (BSCF) perovskite solid solutions. The results are compared with previous studies on a prototype SrTiO{sub 3} perovskite. It is shown that BSCF permits accommodation of a high concentration of defects and cation clusters but not antisite defects.

  8. Radiation defects in complex perovskite solid solutions

    Science.gov (United States)

    Kuklja, M. M.; Kotomin, E. A.; Sharia, O.; Mastrikov, Yu. A.; Maier, J.

    2014-05-01

    First principles density functional theory (DFT) based modeling is performed to explore formation energies of a series of point cation and oxygen defects, Frenkel and Schottky disorder, as well as structural disorder in Ba1-xSrxCo1-yFeyO3-δ (BSCF) perovskite solid solutions. The results are compared with previous studies on a prototype SrTiO3 perovskite. It is shown that BSCF permits accommodation of a high concentration of defects and cation clusters but not antisite defects.

  9. Dimensions of defects determined by radiographical testing

    International Nuclear Information System (INIS)

    Oesterberg, J.

    Normally industrial radiography using x-rays or radionuclides gives information on the existence of defects in welds. These defects may in some instances be harmless, the size of the flaw is important. Radiography may be used for determining the thickness of the defect in many cases, by measuring the blackening of the photographic film used. The report gives a theoretical treatment of the problems and goes on to practical examples of the application. For flaws that have a width of at least 0.3 mm, a thickness of the order 0.1 mm can be determined with sufficient accuracy in materials 40 mm thick.(P.Aa.)

  10. FOREWORD International Conference on Defects in Insulating Materials

    Science.gov (United States)

    Valerio, Mário Ernesto Giroldo; Jackson, R. A.

    2010-11-01

    These proceedings represent a sample of the scientific works presented during ICDIM2008, the 16th International Conference on Defects in Insulating Materials, held at the Federal University of Sergipe, Aracaju, Brazil from 24-29 August 2008. The conference was the latest in a series which began at Argonne in 1956, and which has been held most recently in Riga, Latvia (2004) and Johannesburg, South Africa (2000). The conference was also related scientifically to the EURODIM series, which have been held most recently in Milan, Italy (2006), Wroclaw, Poland (2002) and Pecs, Hungary (2010). The aim of the conference was to bring together physicists, chemists and materials scientist to discuss defects in insulating materials and their effect on materials, including their optical, mass/charge transport, energy storage and sensor properties. The conference featured 6 plenary lectures, 60 contributed lectures and about 130 posters. The posters were displayed for the whole conference, but discussed in two three-hour sessions. We are grateful to the International Advisory Committee for suggesting invited speakers and to the Programme Committee for their help in refereeing all the abstracts and choosing the contributed oral contributions. We would also like to thank the Local Organising Committee and the Brazilian Physical Society for their help with local organisation and the online registration/payment process respectively. The chairpersons would like to specially thanks all the sponsors listed below for financial support. The Federal University of Sergipe, one of the public and 'free tuition' Universities of the Country, run by the Brazilian Ministry of Education, were pleased to host this 16th meeting, the first one in Latin America. Mario E G Valerio Conference Chair Robert A Jackson Programme Chair Conference Scope Scope of the Conference was the presentation of the latest investigations on point and extended defects in bulk materials and thin films. Technological

  11. Vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association with Mayer-Rokitansky-Küster-Hauser syndrome in co-occurrence

    DEFF Research Database (Denmark)

    Bjørsum-Meyer, Thomas; Herlin, Morten; Qvist, Niels

    2016-01-01

    Background: The vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser syndrome are rare conditions. We aimed to present two cases with the vertebral defect, anal atresia, cardiac...... defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser co-occurrence from our local surgical center and through a systematic literature search detect published cases. Furthermore, we aimed to collect existing knowledge...... in the embryopathogenesis and genetics in order to discuss a possible link between the vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser syndrome. Case presentation: Our first case was a white girl...

  12. Extended genomes: symbiosis and evolution.

    Science.gov (United States)

    Hurst, Gregory D D

    2017-10-06

    Many aspects of an individual's biology derive from its interaction with symbiotic microbes, which further define many aspects of the ecology and evolution of the host species. The centrality of microbes in the function of individual organisms has given rise to the concept of the holobiont-that an individual's biology is best understood as a composite of the 'host organism' and symbionts within. This concept has been further elaborated to posit the holobiont as a unit of selection. In this review, I critically examine whether it is useful to consider holobionts as a unit of selection. I argue that microbial heredity-the direct passage of microbes from parent to offspring-is a key factor determining the degree to which the holobiont can usefully be considered a level of selection. Where direct vertical transmission (VT) is common, microbes form part of extended genomes whose dynamics can be modelled with simple population genetics, but that nevertheless have subtle quantitative distinctions from the classic mutation/selection model for nuclear genes. Without direct VT, the correlation between microbial fitness and host individual fitness erodes, and microbe fitness becomes associated with host survival only (rather than reproduction). Furthermore, turnover of microbes within a host may lessen associations between microbial fitness with host survival, and in polymicrobial communities, microbial fitness may derive largely from the ability to outcompete other microbes, to avoid host immune clearance and to minimize mortality through phage infection. These competing selection pressures make holobiont fitness a very minor consideration in determining symbiont evolution. Nevertheless, the importance of non-heritable microbes in organismal function is undoubted-and as such the evolutionary and ecological processes giving rise to variation and evolution of the microbes within and between host individuals represent a key research area in biology.

  13. Defects in Arsenic Implanted p + -n- and n + -p- Structures Based on MBE Grown CdHgTe Films

    Science.gov (United States)

    Izhnin, I. I.; Fitsych, E. I.; Voitsekhovskii, A. V.; Korotaev, A. G.; Mynbaev, K. D.; Varavin, V. S.; Dvoretsky, S. A.; Mikhailov, N. N.; Yakushev, M. V.; Bonchyk, A. Yu.; Savytskyy, H. V.; Świątek, Z.

    2018-02-01

    Complex studies of the defect structure of arsenic-implanted (with the energy of 190 keV) Cd x Hg 1-x Te ( x = 0.22) films grown by molecular-beam epitaxy are carried out. The investigations were performed using secondary-ion mass spectroscopy, transmission electron microscopy, optical reflection in the visible region of the spectrum, and electrical measurements. Radiation donor defects were studied in n +- p- and n +- n-structures obtained by implantation and formed on the basis of p-type and n-type materials, respectively, without activation annealing. It is shown that in the layer of the distribution of implanted ions, a layer of large extended defects with low density is formed in the near-surface region followed by a layer of smaller extended defects with larger density. A different character of accumulation of electrically active donor defects in the films with and without a protective graded-gap surface layer has been revealed. It is demonstrated that p +- n- structures are formed on the basis of n-type material upon activation of arsenic in the process of postimplantation thermal annealing with 100% activation of impurity and complete annihilation of radiation donor defects.

  14. Multiplet structure of the defect modes in 1D helical photonic crystals with twist defects

    Energy Technology Data Exchange (ETDEWEB)

    Avendano, C G [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apdo. P 20-364 01000, Mexico DF (Mexico); Ponti, S [Dipartimento di Fisica Politecnico di Torino and INFM, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Reyes, J A [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apdo. P 20-364 01000, Mexico DF (Mexico); Oldano, C [Dipartimento di Fisica Politecnico di Torino and INFM, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

    2005-10-14

    We theoretically analyse the defect modes generated by equispaced twist defects in 1D helical (cholesteric-like) structures within their frequency gap which is such that only the first two of the four eigenwaves 1{sup {+-}}, 2{sup {+-}} are exponentially attenuated. n{sub 0} identical defects generate n{sub 0} different defect modes, each one represented by a linear combination of the four eigenwaves. The components 1{sup +} and 1{sup -} are by far the dominant ones and they are localized near the defect planes. We give exact analytic expressions for the elements of the transfer and scattering matrices of the defect planes, for the functions defining the defect mode when n{sub 0} = 1, and for the defect frequencies when n{sub 0} = 1, 2, 3. In the particular case n{sub 0} = 2 and twist angle {theta} = {pi}/2, the difference between the two defect wavelengths {lambda}{sub d2}, {lambda}{sub d1} depends exponentially on the distance z{sub 1} between the defect planes, going to zero for z{sub 1} {yields} {infinity} and becoming as large as the entire frequency gap for z{sub 1} {yields} 0.

  15. Stimulated luminescence emission from localized recombination in randomly distributed defects

    DEFF Research Database (Denmark)

    Jain, Mayank; Guralnik, Benny; Andersen, Martin Thalbitzer

    2012-01-01

    408–15) which assumes a fixed d → a tunnelling probability for the entire crystal, our model is based on nearest-neighbour recombination within randomly distributed centres. Such a random distribution can occur through the entire volume or within the defect complexes of the dosimeter, and implies...... that the tunnelling probability varies with the donor–acceptor (d–a) separation distance. We first develop an ‘exact kinetic model’ that incorporates this variation in tunnelling probabilities, and evolves both in spatial as well as temporal domains. We then develop a simplified one-dimensional, semi-analytical model...... results in a highly asymmetric TL peak; this peak can be understood to derive from a continuum of several first-order TL peaks. Our model also shows an extended power law behaviour for OSL (or prompt luminescence), which is expected from localized recombination mechanisms in materials with random...

  16. Periconceptional nutrient intakes and risks of conotruncal heart defects

    Science.gov (United States)

    Shaw, Gary M.; Carmichael, Suzan L.; Yang, Wei; Lammer, Edward J.

    2010-01-01

    Evidence exists for an association between maternal use of a vitamin supplement with folic acid in early pregnancy and a reduced risk for offspring with conotruncal heart defects. Few inquiries about periconceptional nutrition, other than folate, and risk of heart defects have been made. Data derived from a population-based case-control study of fetuses and liveborn infants among a cohort of California births between July 1999 and June 2004. In total, 76% of eligible case mothers and 77% of eligible control mothers were interviewed. Cases included 140 with d-transposition of great arteries (dTGA), and 163 with tetralogy of Fallot (TOF). Total number of controls was 698. Self-reported use of vitamins was elicited by questionnaire for the periconceptional period, Dietary nutrient intake was elicited by a well-known food frequency questionnaire. The odds ratio for dTGA associated with supplemental vitamin use was 1.0 (95% confidence interval, 0.7-1.5) and for TOF was 0.9 (0.6-1.3). We observed increased risks associated with lower dietary intakes of linoleic acid, total carbohydrate, and fructose for dTGA, whereas decreased risks were observed for lower intakes of total protein and methionine for TOF. Lower dietary intake of several micronutrients, namely folate, niacin, riboflavin, and vitamins B12, A, and E, even after simultaneous adjustment for other studied nutrients, were associated with increased risks of dTGA, but not for TOF. These associations were observed among women who did not use vitamin supplements periconceptionally. Analytic consideration of several potential confounders did not reveal alternative interpretations of the results. Our population-based case-control study attempted to extend the knowledge base on nutrition and heart defect risk and prevention. PMID:20063270

  17. Dipole oscillations of a Bose-Einstein condensate in the presence of defects and disorder.

    Science.gov (United States)

    Albert, M; Paul, T; Pavloff, N; Leboeuf, P

    2008-06-27

    We consider dipole oscillations of a trapped dilute Bose-Einstein condensate in the presence of a scattering potential consisting either in a localized defect or in an extended disordered potential. In both cases the breaking of superfluidity and the damping of the oscillations are shown to be related to the appearance of a nonlinear dissipative flow. At supersonic velocities the flow becomes asymptotically dissipationless.

  18. Transcriptomic analysis of swarm motility phenotype of Salmonella enterica serovar Typhimurium mutant defective in periplasmic glucan synthesis

    Science.gov (United States)

    Movement of food-borne pathogens on moist surfaces enables them to migrate towards more favorable niches and facilitate their survival for extended periods of time. Salmonella enterica serovar Typhimurium mutants defective in OPG synthesis are unable to exhibit motility on moist surfaces (swarming) ...

  19. Point defects dynamics in a stress field

    International Nuclear Information System (INIS)

    Smetniansky de De Grande, Nelida.

    1989-01-01

    The dependence of anisotropic defect diffusion on stress is studied for a hexagonal close packed (hcp) material under irradiation and uniaxially stressed. The diffusion is described as a discrete process of thermally activated jumps. It is shown that the presence of an external stress field enhances the intrinsic anisotropic diffusion, being this variation determined by the defect dipole tensors' symmetry in the equilibrium and saddle point configurations. Also, the point defect diffusion equations to sinks, like edge dislocations and spherical cavities, are solved and the sink strengths are calculated. The conclusion is that the dynamics of the interaction between defects and sinks is controlled by the changes in diffusivity induced by stress fields. (Author) [es

  20. International conference on defects in insulating crystals

    Energy Technology Data Exchange (ETDEWEB)

    1977-01-01

    Short summaries of conference papers are presented. Some of the conference topics included transport properties, defect levels, superionic conductors, radiation effects, John-Teller effect, electron-lattice interactions, and relaxed excited states. (SDF)

  1. Holographic entanglement entropy of surface defects

    Energy Technology Data Exchange (ETDEWEB)

    Gentle, Simon A.; Gutperle, Michael; Marasinou, Chrysostomos [Department of Physics and Astronomy, University of California,Los Angeles, CA 90095 (United States)

    2016-04-12

    We calculate the holographic entanglement entropy in type IIB supergravity solutions that are dual to half-BPS disorder-type surface defects in N=4 supersymmetric Yang-Mills theory. The entanglement entropy is calculated for a ball-shaped region bisected by a surface defect. Using the bubbling supergravity solutions we also compute the expectation value of the defect operator. Combining our result with the previously-calculated one-point function of the stress tensor in the presence of the defect, we adapt the calculation of Lewkowycz and Maldacena http://dx.doi.org/10.1007/JHEP05(2014)025 to obtain a second expression for the entanglement entropy. Our two expressions agree up to an additional term, whose possible origin and significance is discussed.

  2. Holographic entanglement entropy of surface defects

    Science.gov (United States)

    Gentle, Simon A.; Gutperle, Michael; Marasinou, Chrysostomos

    2016-04-01

    We calculate the holographic entanglement entropy in type IIB supergravity solutions that are dual to half-BPS disorder-type surface defects in N=4 supersymmetric Yang-Mills theory. The entanglement entropy is calculated for a ball-shaped region bisected by a surface defect. Using the bubbling supergravity solutions we also compute the expectation value of the defect operator. Combining our result with the previously-calculated one-point function of the stress tensor in the presence of the defect, we adapt the calculation of Lewkowycz and Maldacena [1] to obtain a second expression for the entanglement entropy. Our two expressions agree up to an additional term, whose possible origin and significance is discussed.

  3. International conference on defects in insulating crystals

    International Nuclear Information System (INIS)

    1977-01-01

    Short summaries of conference papers are presented. Some of the conference topics included transport properties, defect levels, superionic conductors, radiation effects, John-Teller effect, electron-lattice interactions, and relaxed excited states

  4. Electronic structure of point defects in semiconductors

    International Nuclear Information System (INIS)

    Bruneval, Fabien

    2014-01-01

    This 'Habilitation a diriger des Recherches' memoir presents most of my scientific activities during the past 7 years, in the field of electronic structure calculations of defects in solids. Point defects (vacancies, interstitials, impurities) in functional materials are a key parameter to determine if these materials will actually fill the role they have been assigned or not. Indeed, the presence of defects cannot be avoided when the temperature is increased or when the material is subjected to external stresses, such as irradiation in the nuclear reactors and in artificial satellites with solar radiations. However, in many cases, defects are introduced in the materials on purpose to tune the electronic transport, optical or even magnetic properties. This procedure is called the doping of semiconductors, which is the foundation technique for transistors, diodes, or photovoltaic cells. However, doping is not always straightforward and unexpected features may occur, such as doping asymmetry or Fermi level pinning, which can only be explained by complex phenomena involving different types of defects or complexes of defects. In this context, the calculations of electronic structure ab initio is an ideal tool to complement the experimental observations, to gain the understanding of phenomena at the atomic level, and even to predict the properties of defects. The power of the ab initio calculations comes from their ability to describe any system of electrons and nuclei without any specific adjustment. But although there is a strong need for numerical simulations in this field, the ab initio calculations for defects are still under development as of today. The work presented in this memoir summarizes my contributions to methodological developments on this subject. These developments have followed two main tracks. The first topic is the better understanding of the unavoidable finite size effects. Indeed, defects in semiconductors or insulators are generally present in

  5. Intrinsic defects in 3D printed materials

    OpenAIRE

    Bolton, Christopher; Dagastine, Raymond

    2015-01-01

    We discuss the impact of bulk structural defects on the coherence, phase and polarisation of light passing through transparent 3D printed materials fabricated using a variety of commercial print technologies.

  6. Genetic Counseling for Congenital Heart Defects

    Science.gov (United States)

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Genetic Counseling for Congenital Heart Defects Updated:Jan 19,2018 ... person with congenital heart disease considers having children. Genetic counseling can help answer these questions and address your ...

  7. Holographic entanglement entropy of surface defects

    International Nuclear Information System (INIS)

    Gentle, Simon A.; Gutperle, Michael; Marasinou, Chrysostomos

    2016-01-01

    We calculate the holographic entanglement entropy in type IIB supergravity solutions that are dual to half-BPS disorder-type surface defects in N=4 supersymmetric Yang-Mills theory. The entanglement entropy is calculated for a ball-shaped region bisected by a surface defect. Using the bubbling supergravity solutions we also compute the expectation value of the defect operator. Combining our result with the previously-calculated one-point function of the stress tensor in the presence of the defect, we adapt the calculation of Lewkowycz and Maldacena http://dx.doi.org/10.1007/JHEP05(2014)025 to obtain a second expression for the entanglement entropy. Our two expressions agree up to an additional term, whose possible origin and significance is discussed.

  8. Dural sinus filling defect: intrasigmoid encephalocele

    Science.gov (United States)

    Karatag, Ozan; Cosar, Murat; Kizildag, Betul; Sen, Halil Murat

    2013-01-01

    Filling defects of dural venous sinuses are considered to be a challenging problem especially in case of symptomatic patients. Many lesions have to be ruled out such as sinus thrombosis, arachnoid granulations and tumours. Encephalocele into dural sinus is also a rare cause of these filling defects of dural sinuses. Here, we report an extremely rare case with spontaneous occult invagination of temporal brain tissue into the left sigmoid sinus and accompanying cerebellar ectopia. PMID:24311424

  9. 49 CFR 215.103 - Defective wheel.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Defective wheel. 215.103 Section 215.103... § 215.103 Defective wheel. A railroad may not place or continue in service a car, if— (a) A wheel flange... tread of the wheel; (b) The height of a wheel flange on the car, from the tread to the top of the flange...

  10. (AJST) MULTIPLE DEFECT DISTRIBUTIONS ON WEIBULL ...

    African Journals Online (AJOL)

    Weibull model for fatigue life distributions of unfiltered and filtered castings. Statistical parameters. Old oxide film defects. (o). Slip mechanisms. (s). Young and old oxide film defects (o). Pores attached to oxide films. (p). Characteristics fatigue life,. N c (cycles). 3.8 x 10. 5. 5.3 x 10. 6. 3.3 x 10. 5. 2.3 x 10. 5. Weibull modulus, b.

  11. Defect core detection in radiata pine logs

    International Nuclear Information System (INIS)

    Wallace, G.

    1993-01-01

    Internal defect cores in Pinus radiata logs arise primarily from the practice in New Zealand of pruning trees to increase the amount of clear wood. Realising the benefits of this practice when milling the logs is hampered by the lack of a practical method for detecting the defect cores. This report attempts to establish industry requirements for detections and examine techniques which may be suitable. Some trials of a novel technique are described. (author) 19 refs.; 11 figs

  12. Radioactive fallout and neural tube defects

    Directory of Open Access Journals (Sweden)

    Nejat Akar

    2015-10-01

    Full Text Available Possible link between radioactivity and the occurrence of neural tube defects is a long lasting debate since the Chernobyl nuclear fallout in 1986. A recent report on the incidence of neural defects in the west coast of USA, following Fukushima disaster, brought another evidence for effect of radioactive fallout on the occurrence of NTD’s. Here a literature review was performed focusing on this special subject.

  13. EUV actinic defect inspection and defect printability at the sub-32 nm half pitch

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Sungmin; Kearney, Patrick; Wurm, Stefan; Goodwin, Frank; Han, Hakseung; Goldberg, Kenneth; Mochi, Iacopp; Gullikson, Eric M.

    2009-08-01

    Extreme ultraviolet (EUV) mask blanks with embedded phase defects were inspected with a reticle actinic inspection tool (AIT) and the Lasertec M7360. The Lasertec M7360, operated at SEMA TECH's Mask Blank Development Center (MBDC) in Albany, NY, has a sensitivity to multilayer defects down to 40-45 nm, which is not likely sufficient for mask blank development below the 32 nm half-pitch node. Phase defect printability was simulated to calculate the required defect sensitivity for a next generation blank inspection tool to support reticle development for the sub-32 nm half-pitch technology node. Defect mitigation technology is proposed to take advantage of mask blanks with some defects. This technology will reduce the cost of ownership of EUV mask blanks. This paper will also discuss the kind of infrastructure that will be required for the development and mass production stages.

  14. Reduction in Defect Content of ODS Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ritherdon, J

    2001-05-15

    The work detailed within this report is a continuation of earlier work carried out under contract number 1DX-SY382V. The earlier work comprises a literature review of the sources and types of defects found principally in Fe-based ODS alloys as well as experimental work designed to identify defects in the prototype ODS-Fe{sub 3}Al alloy, deduce their origins and to recommend methods of defect reduction. The present work is an extension of the experimental work already reported and concentrates on means of reduction of defects already identified rather than the search for new defect types. This report also includes results gathered during powder separation trials, conducted by the University of Groningen, Netherlands and coordinated by the University of Liverpool, involving the separation of different metallic powders in terms of their differing densities. The scope and objectives of the present work were laid out in the technical proposal ''Reduction in Defect Content in ODS Alloys-III''. All the work proposed in the ''Statement of Work'' section of the technical proposal has been carried out and all work extra to the ''Statement of Work'' falls within the context of an ODS-Fe{sub 3}Al alloy of improved overall quality and potential creep performance in the consolidated form. The outturn of the experimental work performed is reported in the following sections.

  15. Preface of 16th International conference on Defects, Recognition, Imaging and Physics in Semiconductors

    Science.gov (United States)

    Yang, Deren; Xu, Ke

    2016-11-01

    The 16th International conference on Defects-Recognition, Imaging and Physics in Semiconductors (DRIP-XVI) was held at the Worldhotel Grand Dushulake in Suzhou, China from 6th to 10th September 2015, around the 30th anniversary of the first DRIP conference. It was hosted by the Suzhou Institute of Nano-tech and Nano-bionics (SINANO), Chinese Academy of Sciences. On this occasion, about one hundred participants from nineteen countries attended the event. And a wide range of subjects were addressed during the conference: physics of point and extended defects in semiconductors: origin, electrical, optical and magnetic properties of defects; diagnostics techniques of crystal growth and processing of semiconductor materials (in-situ and process control); device imaging and mapping to evaluate performance and reliability; defect analysis in degraded optoelectronic and electronic devices; imaging techniques and instruments (proximity probe, x-ray, electron beam, non-contact electrical, optical and thermal imaging techniques, etc.); new frontiers of atomic-scale-defect assessment (STM, AFM, SNOM, ballistic electron energy microscopy, TEM, etc.); new approaches for multi-physic-parameter characterization with Nano-scale space resolution. Within these subjects, there were 58 talks, of which 18 invited, and 50 posters.

  16. Design of defect spins in piezoelectric aluminum nitride for solid-state hybrid quantum technologies.

    Science.gov (United States)

    Seo, Hosung; Govoni, Marco; Galli, Giulia

    2016-02-15

    Spin defects in wide-band gap semiconductors are promising systems for the realization of quantum bits, or qubits, in solid-state environments. To date, defect qubits have only been realized in materials with strong covalent bonds. Here, we introduce a strain-driven scheme to rationally design defect spins in functional ionic crystals, which may operate as potential qubits. In particular, using a combination of state-of-the-art ab-initio calculations based on hybrid density functional and many-body perturbation theory, we predicted that the negatively charged nitrogen vacancy center in piezoelectric aluminum nitride exhibits spin-triplet ground states under realistic uni- and bi-axial strain conditions; such states may be harnessed for the realization of qubits. The strain-driven strategy adopted here can be readily extended to a wide range of point defects in other wide-band gap semiconductors, paving the way to controlling the spin properties of defects in ionic systems for potential spintronic technologies.

  17. Point defects and composition in hexagonal group-III nitride monolayers: A first-principles calculation

    Science.gov (United States)

    Gao, Han; Ye, Han; Yu, Zhongyuan; Zhang, Yunzhen; Liu, Yumin; Li, Yinfeng

    2017-12-01

    In this paper, we systematically investigate the structural, electronic and magnetic properties of hexagonal group-III nitride monolayers with point defects and alloying on the basis of first-principles calculations. Six typical point defects including three vacancies and three antisites are modeled in pure AlN, GaN and InN monolayers. The defect-induced modifications of band gaps and magnetic properties are demonstrated. The vacancy of nitrogen, with lowest formation energy, metalizes the semiconducting nitride monolayers. The defects losing single group-III atom introduce net magnetic moment to the systems, while others maintain non-magnetic. For ordered alloy monolayers, the AlGaN and InGaN systems are taken into consideration. The compositional variation is achieved by atomic substitution in supercells with different sizes. We find that the lattice constant and cohesive energy follow good linear relation with concentration while a slight bowing effect is observed for the band gap. These results provide a development in defective and alloy nitride monolayers and extend the potential applications.

  18. Influence of defects on the thermal conductivity of compressed LiF

    Energy Technology Data Exchange (ETDEWEB)

    Jones, R. E. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Ward, D. K. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2018-02-08

    We report defect formation in LiF, which is used as an observation window in ramp and shock experiments, has significant effects on its transmission properties. Given the extreme conditions of the experiments it is hard to measure the change in transmission directly. Using molecular dynamics, we estimate the change in conductivity as a function of the concentration of likely point and extended defects using a Green-Kubo technique with careful treatment of size effects. With this data, we form a model of the mean behavior and its estimated error; then, we use this model to predict the conductivity of a large sample of defective LiF resulting from a direct simulation of ramp compression as a demonstration of the accuracy of its predictions. Given estimates of defect densities in a LiF window used in an experiment, the model can be used to correct the observations of thermal energy through the window. Also, the methodology we develop is extensible to modeling, with quantified uncertainty, the effects of a variety of defects on the thermal conductivity of solid materials.

  19. Influence of defects on the thermal conductivity of compressed LiF

    Science.gov (United States)

    Jones, R. E.; Ward, D. K.

    2018-02-01

    Defect formation in LiF, which is used as an observation window in ramp and shock experiments, has significant effects on its transmission properties. Given the extreme conditions of the experiments it is hard to measure the change in transmission directly. Using molecular dynamics, we estimate the change in conductivity as a function of the concentration of likely point and extended defects using a Green-Kubo technique with careful treatment of size effects. With this data, we form a model of the mean behavior and its estimated error; then, we use this model to predict the conductivity of a large sample of defective LiF resulting from a direct simulation of ramp compression as a demonstration of the accuracy of its predictions. Given estimates of defect densities in a LiF window used in an experiment, the model can be used to correct the observations of thermal energy through the window. In addition, the methodology we develop is extensible to modeling, with quantified uncertainty, the effects of a variety of defects on the thermal conductivity of solid materials.

  20. Multiscale modelling of the interaction of hydrogen with interstitial defects and dislocations in BCC tungsten

    Science.gov (United States)

    De Backer, A.; Mason, D. R.; Domain, C.; Nguyen-Manh, D.; Marinica, M.-C.; Ventelon, L.; Becquart, C. S.; Dudarev, S. L.

    2018-01-01

    In a fusion tokamak, the plasma of hydrogen isotopes is in contact with tungsten at the surface of a divertor. In the bulk of the material, the hydrogen concentration profile tends towards dynamic equilibrium between the flux of incident ions and their trapping and release from defects, either native or produced by ion and neutron irradiation. The dynamics of hydrogen exchange between the plasma and the material is controlled by pressure, temperature, and also by the energy barriers characterizing hydrogen diffusion in the material, trapping and de-trapping from defects. In this work, we extend the treatment of interaction of hydrogen with vacancy-type defects, and investigate how hydrogen is trapped by self-interstitial atom defects and dislocations. The accumulation of hydrogen on dislocation loops and dislocations is assessed using a combination of density functional theory (DFT), molecular dynamics with empirical potentials, and linear elasticity theory. The equilibrium configurations adopted by hydrogen atoms in the core of dislocations as well as in the elastic fields of defects, are modelled by DFT. The structure of the resulting configurations can be rationalised assuming that hydrogen atoms interact elastically with lattice distortions and that they interact between themselves through short-range repulsion. We formulate a two-shell model for hydrogen interaction with an interstitial defect of any size, which predicts how hydrogen accumulates at defects, dislocation loops and line dislocations at a finite temperature. We derive analytical formulae for the number of hydrogen atoms forming the Cottrell atmosphere of a mesoscopic dislocation loop or an edge dislocation. The solubility of hydrogen as a function of temperature, pressure and the density of dislocations exhibits three physically distinct regimes, dominated by the solubility of hydrogen in a perfect lattice, its retention at dislocation cores, and trapping by long-range elastic fields of

  1. Reconstruction of mandibular defects using nonvascularized autogenous bone graft in Nigerians

    Directory of Open Access Journals (Sweden)

    Kizito Chioma Ndukwe

    2014-01-01

    Full Text Available Objectives: The aim of this study is to evaluate the success rate and complications of mandibular reconstruction with nonvascularized bone graft in Ile-Ife, Nigeria. Patients and Methods: A total of 25 patients who underwent reconstruction of mandibular discontinuity defects between January 2003 and February 2012, at the Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife constituted the study sample. Relevant information was retrieved from the patients′ records. This information include patients′ demographics (age and sex as well as the type of mandibular defect, cause of the defect, type of mandibular resection done, source of the bone graft used, and the method of graft immobilization. Morbidity associated with the graft procedures were assessed by retrieving information on graft failures, length of hospital stay following surgery, rehabilitation device used and associated graft donor and recipient site complications. Result: There were 12 males and 13 females with a male:female ratio was 1:1.1. The age of the patients ranged from 13 to 73 years with a mean age for males 32.7 ± standard deviation (SD 12.9 and for females 35.0 ± SD 17.1. Jaw defect was caused by resection for tumours and other jaw pathologies in 92% of cases. Complete symphyseal involvement defect was the most common defect recorded 11 (44%. Reconstruction with nonvascularized rib graft accounted for 68% of cases while iliac crest graft was used in 32% of the patients. Successful take of the grafts was recorded in 22 patients while three cases failed. Wound dehiscence (two patients and postoperative wound infection (eight patients were the most common complications recorded. Conclusion: The use of nonvascularized graft is still relevant in the reconstruction of large mandibular defects caused by surgical ablation of benign conditions in Nigerians. Precise surgical planning and execution, extended antibiotic therapy, and meticulous postoperative care

  2. Folate-related gene variants in Irish families affected by neural tube defects

    Directory of Open Access Journals (Sweden)

    Ridgely eFisk Green

    2013-11-01

    Full Text Available Periconceptional folic acid use can often prevent neural tube defects (NTDs. Variants of genes involved in folate metabolism in mothers and children have been associated with occurrence of NTDs. We identified Irish families with individuals affected by neural tube defects. In these families, we observed that neural tube defects and birth defects overall occurred at a higher rate in the maternal lineage compared with the paternal lineage. The goal of this study was to look for evidence for genetic effects that could explain the discrepancy in the occurrence of these birth defects in the maternal vs. paternal lineage. We genotyped blood samples from 322 individuals from NTD-affected Irish families, identified through their membership in spina bifida associations. We looked for differences in distribution in maternal vs. paternal lineages of five genetic polymorphisms: the DHFR 19bp deletion, MTHFD1 1958G>A, MTHFR 1298A>C, MTHFR 677C>T, and SLC19A1 80A>G. In addition to looking at genotypes individually, we determined the number of genotypes associated with decreased folate metabolism in each relative (risk genotypes and compared the distribution of these genotypes in maternal vs. paternal relatives. Overall, maternal relatives had a higher number of genotypes associated with lower folate metabolism than paternal relatives (p=0.017. We expected that relatives would share the same risk genotype as the individuals with NTDs and/or their mothers. However, we observed that maternal relatives had an over-abundance of any risk genotype, rather than one specific genotype. The observed genetic effects suggest an epigenetic mechanism in which decreased folate metabolism results in epigenetic alterations related to the increased rate of NTDs and other birth defects seen in the maternal lineage. Future studies on the etiology of NTDs and other birth defects could benefit from including multigenerational extended families, in order to explore potential

  3. System for Analyzing Microscopic Defects and Defect Propagation Due to Aging, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — New technology is needed for sensing and characterizing incipient defects, and assessing the effects of aging in aerospace components. Next generation materials,...

  4. Evaluation of detectable defect size for inner defect of pressure vessel using laser speckle

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyeoung Suk; Seon, Sang Woo; Choi, Tae Ho; Kang, Chan Geun; Na, Man Gyun; Jung, Hyun Chul [Chsoun University, Gwangju (Korea, Republic of)

    2014-04-15

    Pressure vessels are used in various industrial fields. If a defect occurs on the inner or outer surface of a pressure vessel, it may cause a massive accident. A defect on the outer surface can be detected by visual inspection. However, a defect on the inner surface is generally impossible to detect with visual inspection. Nondestructive testing can be used to detect this type of defect. Laser speckle shearing interferometry is one nondestructive testing method that can optically detect a defect; its advantages include noncontact, full field, and real time inspection. This study evaluated the detectable size for an internal defect of a pressure vessel. The material of the pressure vessel was ASTM A53 Gr.B. The internal defect was detected when the pressure vessel was loaded by internal pressure controlled by a pneumatic system. The internal pressure was controlled from 0.2 MPa to 0.6 MPa in increments of 0.2 MPa. The results confirmed that an internal defect with a 25 % defect depth could be detected even at 0.2 MPa pressure variation.

  5. Multiscale crystal defect dynamics: A coarse-grained lattice defect model based on crystal microstructure

    Science.gov (United States)

    Lyu, Dandan; Li, Shaofan

    2017-10-01

    Crystal defects have microstructure, and this microstructure should be related to the microstructure of the original crystal. Hence each type of crystals may have similar defects due to the same failure mechanism originated from the same microstructure, if they are under the same loading conditions. In this work, we propose a multiscale crystal defect dynamics (MCDD) model that models defects by considering its intrinsic microstructure derived from the microstructure or material genome of the original perfect crystal. The main novelties of present work are: (1) the discrete exterior calculus and algebraic topology theory are used to construct a scale-up (coarse-grained) dual lattice model for crystal defects, which may represent all possible defect modes inside a crystal; (2) a higher order Cauchy-Born rule (up to the fourth order) is adopted to construct atomistic-informed constitutive relations for various defect process zones, and (3) an hierarchical strain gradient theory based finite element formulation is developed to support an hierarchical multiscale cohesive (process) zone model for various defects in a unified formulation. The efficiency of MCDD computational algorithm allows us to simulate dynamic defect evolution at large scale while taking into account atomistic interaction. The MCDD model has been validated by comparing of the results of MCDD simulations with that of molecular dynamics (MD) in the cases of nanoindentation and uniaxial tension. Numerical simulations have shown that MCDD model can predict dislocation nucleation induced instability and inelastic deformation, and thus it may provide an alternative solution to study crystal plasticity.

  6. Multiscale simulations of defect dipole-enhanced electromechanical coupling at dilute defect concentrations

    Science.gov (United States)

    Liu, Shi; Cohen, R. E.

    2017-08-01

    The role of defects in solids of mixed ionic-covalent bonds such as ferroelectric oxides is complex. Current understanding of defects on ferroelectric properties at the single-defect level remains mostly at the empirical level, and the detailed atomistic mechanisms for many defect-mediated polarization-switching processes have not been convincingly revealed quantum mechanically. We simulate the polarization-electric field (P-E) and strain-electric field (ɛ-E) hysteresis loops for BaTiO3 in the presence of generic defect dipoles with large-scale molecular dynamics and provide a detailed atomistic picture of the defect dipole-enhanced electromechanical coupling. We develop a general first-principles-based atomistic model, enabling a quantitative understanding of the relationship between macroscopic ferroelectric properties and dipolar impurities of different orientations, concentrations, and dipole moments. We find that the collective orientation of dipolar defects relative to the external field is the key microscopic structure feature that strongly affects materials hardening/softening and electromechanical coupling. We show that a small concentration (≈0.1 at. %) of defect dipoles dramatically improves electromechanical responses. This offers the opportunity to improve the performance of inexpensive polycrystalline ferroelectric ceramics through defect dipole engineering for a range of applications including piezoelectric sensors, actuators, and transducers.

  7. Automated Heuristic Defect Classification (AHDC) for haze-induced defect growth management and mask requalification

    Science.gov (United States)

    Munir, Saghir; Qidwai, Gul

    2012-03-01

    This article presents results from a heuristic automated defect classification algorithm for reticle inspection that mimics the classification rules. AHDC does not require CAD data, thus it can be rapidly deployed in a high volume production environment without the need for extensive design data management. To ensure classification consistency a software framework tracks every defect in repeated inspections. Through its various image based derived metrics it is shown that such a system manages and tracks repeated defects in applications such as haze induced defect growth.

  8. An extended five-stream model for diffusion of ion-implanted dopants in monocrystalline silicon

    International Nuclear Information System (INIS)

    Khina, B.B.

    2007-01-01

    Low-energy high-dose ion implantation of different dopants (P, Sb, As, B and others) into monocrystalline silicon with subsequent thermal annealing is used for the formation of ultra-shallow p-n junctions in modern VLSI circuit technology. During annealing, dopant activation and diffusion in silicon takes place. The experimentally observed phenomenon of transient enhanced diffusion (TED), which is typically ascribed to the interaction of diffusing species with non-equilibrium point defects accumulated in silicon due to ion damage, and formation of small clusters and extended defects, hinders further down scaling of p-n junctions in VLSI circuits. TED is currently a subject of extensive experimental and theoretical investigation in many binary and multicomponent systems. However, the state-of-the-art mathematical models of dopant diffusion, which are based on the so-called 'five-stream' approach, and modern TCAD software packages such as SUPREM-4 (by Silvaco Data Systems, Ltd.) that implement these models encounter severe difficulties in describing TED. Solving the intricate problem of TED suppression and development of novel regimes of ion implantation and rapid thermal annealing is impossible without elaboration of new mathematical models and computer simulation of this complex phenomenon. In this work, an extended five-stream model for diffusion in silicon is developed which takes into account all possible charge states of point defects (vacancies and silicon self-interstitials) and diffusing pairs 'dopant atom-vacancy' and 'dopant atom-silicon self-interstitial'. The model includes the drift terms for differently charged point defects and pairs in the internal electric field and the kinetics of interaction between unlike 'species' (generation and annihilation of pairs and annihilation of point defects). Expressions for diffusion coefficients and numerous sink/source terms that appear in the non-linear, non-steady-state reaction-diffusion equations are derived

  9. Structure Defect Property Relationships in Binary Intermetallics

    Science.gov (United States)

    Medasani, Bharat; Ding, Hong; Chen, Wei; Persson, Kristin; Canning, Andrew; Haranczyk, Maciej; Asta, Mark

    2015-03-01

    Ordered intermetallics are light weight materials with technologically useful high temperature properties such as creep resistance. Knowledge of constitutional and thermal defects is required to understand these properties. Vacancies and antisites are the dominant defects in the intermetallics and their concentrations and formation enthalpies could be computed by using first principles density functional theory and thermodynamic formalisms such as dilute solution method. Previously many properties of the intermetallics such as melting temperatures and formation enthalpies were statistically analyzed for large number of intermetallics using structure maps and data mining approaches. We undertook a similar exercise to establish the dependence of the defect properties in binary intermetallics on the underlying structural and chemical composition. For more than 200 binary intermetallics comprising of AB, AB2 and AB3 structures, we computed the concentrations and formation enthalpies of vacancies and antisites in a small range of stoichiometries deviating from ideal stoichiometry. The calculated defect properties were datamined to gain predictive capabilities of defect properties as well as to classify the intermetallics for their suitability in high-T applications. Supported by the US DOE under Contract No. DEAC02-05CH11231 under the Materials Project Center grant (Award No. EDCBEE).

  10. Coating defect evaluation based on stimulated thermography

    Science.gov (United States)

    Palumbo, Davide; Tamborrino, Rosanna; Galietti, Umberto

    2017-05-01

    Thermal Barrier Coatings are used to protect the materials from severe temperature and chemical environments. In particular, these materials are used in the engineering fields where high temperatures, corrosive environments and high mechanical stress are required. Defects present between substrate material and coating, as detachments may cause the break of coating and the consequent possibility to exposure the substrate material to the environment conditions. The capability to detect the defect zones with non-destructive techniques could allow the maintenance of coated components with great advantages in terms of costs and prediction of fatigue life. In this work, two different heat sources and two different thermographic techniques have been used to detect the adhesion defects among the base material and the coating. Moreover, an empirical thermographic method has been developed to evaluate the thickness of the thermal coating and to discriminate between an unevenness of the thickness and a defect zone. The study has been conducted on circular steel specimens with simulated adhesion defect and on specimens prepared with different thicknesses of thermal barrier coating.

  11. Ultrasonic NDE Simulation for Composite Manufacturing Defects

    Science.gov (United States)

    Leckey, Cara A. C.; Juarez, Peter D.

    2016-01-01

    The increased use of composites in aerospace components is expected to continue into the future. The large scale use of composites in aerospace necessitates the development of composite-appropriate nondestructive evaluation (NDE) methods to quantitatively characterize defects in as-manufactured parts and damage incurred during or post manufacturing. Ultrasonic techniques are one of the most common approaches for defect/damage detection in composite materials. One key technical challenge area included in NASA's Advanced Composite's Project is to develop optimized rapid inspection methods for composite materials. Common manufacturing defects in carbon fiber reinforced polymer (CFRP) composites include fiber waviness (in-plane and out-of-plane), porosity, and disbonds; among others. This paper is an overview of ongoing work to develop ultrasonic wavefield based methods for characterizing manufacturing waviness defects. The paper describes the development and implementation of a custom ultrasound simulation tool that is used to model ultrasonic wave interaction with in-plane fiber waviness (also known as marcelling). Wavefield data processing methods are applied to the simulation data to explore possible routes for quantitative defect characterization.

  12. Defect kinetics in novel detector materials

    CERN Document Server

    MacEvoy, B C

    2000-01-01

    Silicon particle detectors will be used extensively in experiments at the CERN Large Hadron Collider, where unprecedented particle fluences will cause significant atomic displacement damage. We present a model of the evolution of defect concentrations and consequent electrical behaviour in "novel" detector materials with various oxygen and carbon impurity concentrations. The divacancy-oxygen (V/sub 2/O) defect is identified as the cause of changes in device characteristics during /sup 60/Co gamma irradiation. In the case of hadron irradiation changes in detector doping concentration (N/sub eff/) are dominated by cluster defects, in particular the divacancy (V/sub 2/), which exchange charge directly via a non-Shockley-Read- Hall mechanism. The V/sub 2/O defect also contributes to Ne/sub eff/. This defect is more copiously produced during 24 GeV/c proton irradiation than during 1 MeV neutron irradiation on account of the higher vacancy introduction rate, hence the radiation hardness of materials is more sensiti...

  13. Anomalous rapid defect annihilation in self-assembled nanopatterns by defect melting.

    Science.gov (United States)

    Kim, Bong Hoon; Park, So Jung; Jin, Hyeong Min; Kim, Ju Young; Son, Seung-Woo; Kim, Myung-Hyun; Koo, Chong Min; Shin, Jonghwa; Kim, Jaeup U; Kim, Sang Ouk

    2015-02-11

    Molecular self-assembly commonly suffers from dense structural defect formation. Spontaneous defect annihilation in block copolymer (BCP) self-assembly is particularly retarded due to significant energy barrier for polymer chain diffusion and structural reorganization. Here we present localized defect melting induced by blending short neutral random copolymer chain as an unusual method to promote the defect annihilation in BCP self-assembled nanopatterns. Chemically neutral short random copolymer chains blended with BCPs are specifically localized and induce local disordered states at structural defect sites in the self-assembled nanopatterns. Such localized "defect melting" relieves the energy penalty for polymer diffusion and morphology reorganization such that spontaneous defect annihilation by mutual coupling is anomalously accelerated upon thermal annealing. Interestingly, neutral random copolymer chain blending also causes morphology-healing self-assembly behavior that can generate large-area highly ordered 10 nm scale nanopattern even upon poorly defined defective prepatterns. Underlying mechanisms of the unusual experimental findings are thoroughly investigated by three-dimensional self-consistent field theory calculation.

  14. Extended Producer Responsibility in the Aviation Sector

    OpenAIRE

    Brito, Marisa; Laan, Erwin; Irion, B.D.

    2007-01-01

    textabstractIn this paper we investigate recent initiatives with respect to extended producer responsibility in the aviation sector. We compare those with the existing practices in the automobile sector and the emerging regulations in the shipping sector. We describe the challenges and the lessons to be learned from the evolution and state of extended producer responsibility in these two industries.

  15. Extended, Embodied Cognition and Second Language Acquisition

    Science.gov (United States)

    Atkinson, Dwight

    2010-01-01

    A "cognitivist" approach to cognition has traditionally dominated second language acquisition (SLA) studies. In this article, I examine two alternative approaches--"extended cognition" and "embodied cognition"--for how they might help us conceptualize SLA. More specifically, I present: (i) summaries of extended and embodied cognition, followed by…

  16. ROLE OF DATA MINING CLASSIFICATION TECHNIQUE IN SOFTWARE DEFECT PREDICTION

    OpenAIRE

    Dr.A.R.Pon Periyasamy; Mrs A.Misbahulhuda

    2017-01-01

    Software defect prediction is the process of locating defective modules in software. Software quality may be a field of study and apply that describes the fascinating attributes of software package product. The performance should be excellent with none defects. Software quality metrics are a set of software package metrics that target the standard aspects of the product, process, and project. The software package defect prediction model helps in early detection of defects and contributes to t...

  17. Laterality defects in the national birth defects prevention study 1998-2007 birth prevalence and descriptive epidemiology

    Science.gov (United States)

    Little is known epidemiologically about laterality defects. Using data from the National Birth Defects Prevention Study (NBDPS), a large multi-site case-control study of birth defects, we analyzed prevalence and selected characteristics in children born with laterality defects born from 1998 to 2007...

  18. Maternal autoimmune disease and birth defects in the National Birth Defects Prevention Study.

    Science.gov (United States)

    Howley, Meredith M; Browne, Marilyn L; Van Zutphen, Alissa R; Richardson, Sandra D; Blossom, Sarah J; Broussard, Cheryl S; Carmichael, Suzan L; Druschel, Charlotte M

    2016-11-01

    Little is known about the association between maternal autoimmune disease or its treatment and the risk of birth defects. We examined these associations using data from the National Birth Defects Prevention Study, a multi-site, population-based, case-control study. Analyses included 25,116 case and 9897 unaffected control infants with estimated delivery dates between 1997 and 2009. Information on autoimmune disease, medication use, and other pregnancy exposures was collected by means of telephone interview. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for birth defects with five or more exposed cases; crude ORs and exact 95% CIs were estimated for birth defects with three to four exposed cases. Autoimmune disease was reported by 373 mothers (279 case and 94 control mothers). The majority of birth defects evaluated were not associated with autoimmune disease; however, a statistically significant association between maternal autoimmune disease and encephalocele was observed (OR, 4.64; 95% CI, 1.95-11.04). Eighty-two mothers with autoimmune disease used an immune modifying/suppressing medication during pregnancy; this was associated with encephalocele (OR, 7.26; 95% CI, 1.37-24.61) and atrial septal defects (OR, 3.01; 95% CI, 1.16-7.80). Our findings suggest maternal autoimmune disease and treatment are not associated with the majority of birth defects, but may be associated with some defects, particularly encephalocele. Given the low prevalence of individual autoimmune diseases and the rare use of specific medications, we were unable to examine associations of specific autoimmune diseases and medications with birth defects. Other studies are needed to confirm these findings. Birth Defects Research (Part A) 106:950-962, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  19. Cyanotic Congenital Heart Defects – literature review

    Directory of Open Access Journals (Sweden)

    Vlad Drăgoi

    2017-11-01

    Full Text Available Congenital heart defects are one of the most interesting and important chapters regarding abnormal fetal growth pathology. The objective of this article is to present a literature review for the main cyanotic congenital heart defects. The ones presented in the article are: tetralogy of Fallot, transposition of the great vessels, double outlet right ventricle, truncus arteriosus, total anomalous pulmonary venous circulation and additional information regarding very rare malformations such as pentalogy of Cantrell and Uhl anomaly. An early and precise identification of congenital heart defects is an important step in an accurate follow-up of a potential problematic pregnancy. Knowing the sonographic aspect, associated pathology and the current available treatment procedures are vital for the fetal outcome and for the physician to adapt the right management in every situation that might appear during the pregnancy and in the neonatal period.

  20. Defective cerebrovascular autoregulation after carotid endarterectomy

    DEFF Research Database (Denmark)

    Jørgensen, L G; Schroeder, T V

    1993-01-01

    Correction of high grade carotid artery stenosis may result in cerebral hyperperfusion because of defective vascular autoregulation. Thus, transcranial Doppler was used to determine mean arterial flow velocity (Vmean) of the middle cerebral artery in 95 patients before and after carotid endartere......Correction of high grade carotid artery stenosis may result in cerebral hyperperfusion because of defective vascular autoregulation. Thus, transcranial Doppler was used to determine mean arterial flow velocity (Vmean) of the middle cerebral artery in 95 patients before and after carotid...... (130-332)% of the preoperative value (p reduced in symptomatic patients with labetalol, ipsilateral Vmean decreased from 92 (69-124) to 56 (32-93) cm s-1 (p ... that ipsilateral middle cerebral artery mean flow velocity was pressure dependent. This substantiates the hypothesis of defective autoregulation in the ipsilateral hemisphere after carotid endarterectomy, and in turn demonstrates an immediate cessation of symptoms with reduction of arterial pressure even...

  1. Atrioventricular septal defects among infants in Europe

    DEFF Research Database (Denmark)

    Christensen, Nikolas; Andersen, Helle; Garne, Ester

    2013-01-01

    OBJECTIVE: To describe the epidemiology of chromosomal and non-chromosomal cases of atrioventricular septal defects in Europe. METHODS: Data were obtained from EUROCAT, a European network of population-based registries collecting data on congenital anomalies. Data from 13 registries for the period...... 2000-2008 were included. RESULTS: There was a total of 993 cases of atrioventricular septal defects, with a total prevalence of 5.3 per 10,000 births (95% confidence interval 4.1 to 6.5). Of the total cases, 250 were isolated cardiac lesions, 583 were chromosomal cases, 79 had multiple anomalies, 58...... of pregnancy owing to foetal anomaly. Among the groups, additional associated cardiac anomalies were most frequent in heterotaxia cases (38%) and least frequent in chromosomal cases (8%). Coarctation of the aorta was the most common associated cardiac defect. The 1-week survival rate for live births was 94...

  2. Production defects in marine composite structures

    DEFF Research Database (Denmark)

    Hayman, Brian; Berggreen, Christian; Tsouvalis, Nicholas G.

    2007-01-01

    Composite structures are often used when there is a requirement for low weight. Then a key aspect is to be able to take full advantage of the material and utilise it to its limits. To do this it is important to achieve as low a variability as possible in the manufacture of such structures......, and to have a good understanding of the way in which production defects and imperfections influence the structural performance, so that adequate levels of structural safety and reliability can be achieved without having to apply excessively large factors of safety. A review is made of the types of defects...... that arise in the relevant production processes, of their causes and the means that can be used to reduce or eliminate them, and of models that enable the effects of defects and imperfections on structural performance to be predicted....

  3. Ventricular Septal Defect: Peculiarities of Early Neonatal and Postnatal Diagnosis, Clinical Manifestations, Treatment and Prognosis at the Contemporary Stage

    Directory of Open Access Journals (Sweden)

    K.A. Kalashnikova

    2016-05-01

    Full Text Available The article presents the literature data on the incidence, the main clinical manifestations, modern methods for early neonatal and postnatal diagnosis and treatment of ventricular septal defect in children, as well as the prognosis of this disease. According to the International Classification of Diseases, 10th revision, ventricular septal defect is classified as Q21.0 Ventricular septal defect. Incidence. In the overall structure of congenital malformations of the cardiovascular system, ventricular septal defect has about 20 %. Diagnosis. Moderate ventricular septal defect is manifested by shortness of breath, rapid fatigability during feeding, delay in physical development. Significant arterial-venous shunt in the first month of life is accompanied by a transient mild cyanosis when the baby is fed and cries. Infants develop high pulmonary hypertension, circulatory failure, malnutrition. Small noise intensity is typical for newborns in the first weeks or even months of life, which is due to physiologically increased intravascular pulmonary resistance. Systolic murmur is extended to the entire systole with maximum amplitude at the left edge of the sternum at the level of III–IV intercostal spaces. Sclerotic phase of pulmonary hypertension with ventricular septal defect is defined as Eisenmenger reaction. The clinical picture of this disorder depends on the degree of hemodynamic instability caused by the defect parameters, the pressure level in the pulmonary artery, vascular pulmonary resistance, the magnitude and direction of the shunt through the defect. Diagnosis is confirmed by characteristic changes in the electrocardiogram, echocardiography and chest radiograph. Treatment. Small muscular ventricular septal defects often close spontaneously during the first 2 years of life. Drug correction is needed in the development of congestive heart failure. The optimum age for surgery — 5–9 years.

  4. Swimming pool use and birth defect risk.

    Science.gov (United States)

    Agopian, A J; Lupo, Philip J; Canfield, Mark A; Mitchell, Laura E

    2013-09-01

    Swimming during pregnancy is recommended. However, the use of swimming pools is also associated with infection by water-borne pathogens and exposure to water disinfection byproducts, which are 2 mechanisms that are suspected to increase risk for birth defects. Thus, we evaluated the relationship between maternal swimming pool use during early pregnancy and risk for select birth defects in offspring. Data were evaluated for nonsyndromic cases with 1 of 16 types of birth defects (n = 191-1829) and controls (n = 6826) from the National Birth Defects Prevention Study delivered during 2000-2006. Logistic regression analyses were conducted separately for each birth defect type. Separate analyses were conducted to assess any pool use (yes vs no) and frequent use (5 or more occasions in 1 month) during the month before pregnancy through the third month of pregnancy. There was no significant positive association between any or frequent pool use and any of the types of birth defects, even after adjustment for several potential confounders (maternal race/ethnicity, age at delivery, education, body mass index, folic acid use, nulliparity, smoking, annual household income, surveillance center, and season of conception). Frequent pool use was significantly negatively associated with spina bifida (adjusted odds ratio, 0.68; 95% confidence interval, 0.47-0.99). Among offspring of women 20 years old or older, pool use was associated with gastroschisis (adjusted odds ratio, 1.3; 95% confidence interval, 1.0-1.8), although not significantly so. We observed little evidence suggesting teratogenic effects of swimming pool use. Because swimming is a common and suggested form of exercise during pregnancy, these results are reassuring. Copyright © 2013 Mosby, Inc. All rights reserved.

  5. Methods to prevent turbogenerators design elements defects

    Directory of Open Access Journals (Sweden)

    Валентина Володимирівна Шевченко

    2016-11-01

    Full Text Available The paper shows that the determination of a failure probability due to the design, technological and operational drawbacks, as well as due to the turbogenerators working time exceeding from statistics data is inaccurate. Machine park of turbogenerators being rather limited in number, the classification and the distribution of generators into groups is random. It can not be used in practice to identify the pre-emergency state of turbogenerators and their timely stop. Analysis and classification of most frequent defects of turbogenerators has been performed. Methods for assessing such defects and reduction of their development have been offered. The article notes that expenses should be taken into account when setting up a monitoring system to assess the state and to identify defects. Reduction of expenditures on both operating and new turbogenerators must be justified. Rapid return of investments must be ensured. The list of additional tests has been proposed: measurement of infrared radiation outside the body of the turbogenerator for the estimation of the thermal field distribution and the defects of gas coolers identification; vibroacoustic inspection of the stator core and casing to find out the defects in the suspension of the core in the stator casing; analysis of the impurities in the cooling gas and in the dry remains of the drainage products to detect the products of the steel core and the winding insulation wear; value measurement and establishment of the partial discharges formation position; research of vibrations to reveal the cracks in the shaft, circuiting in the rotor windings and defects in the bearings. The paper notes that at upgrading as power grows overall and mounting dimensions must be preserved so that the existing foundation could be used as well as the existing security systems. Therefore, when designing or upgrading turbogenerators with an increase in power it is necessary to introduce new design decisions

  6. Imaging Charge Carriers in Potential-Induced Degradation Defects of c-Si Solar Cells by Scanning Capacitance Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Chun Sheng [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Xiao, Chuanxiao [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Moutinho, Helio R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Johnston, Steven [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Al-Jassim, Mowafak M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yang, X. [Trina Solar; Chen, Y. [Trina Solar; Ye, J. [Chinese Academy of Science

    2018-02-13

    We report on nm-resolution imaging of charge-carrier distribution around local potential-induced degradation (PID) shunting defects using scanning capacitance microscopy. We imaged on cross sections of heavily field-degraded module areas, cored out and selected by mm-scale photoluminescence imaging. We found localized areas with abnormal carrier behavior induced by the PID defects: the apparent n-type carrier extends vertically into the absorber to ~1-2 um from the cell surface, and laterally in similar lengths; in defect-free areas, the n-type carrier extends ~0.5 um, which is consistent with the junction depth. For comparison, we also investigated areas of the same module exhibiting the least PID stress, and we found no such heavily damaged junction area. Instead, we found slightly abnormal carrier behavior, where the carrier-type inversion in the absorber did not occur, but the p-type carrier concentration changed slightly in a much smaller lateral length of ~300 nm. These nano-electrical findings may indicate a possible mechanism that the existing extended defects, which may not be significantly harmful to cell performance, can be changed by PID to heavily damaged junction areas.

  7. Visual detection of defects in solder joints

    Science.gov (United States)

    Blaignan, V. B.; Bourbakis, Nikolaos G.; Moghaddamzadeh, Ali; Yfantis, Evangelos A.

    1995-03-01

    The automatic, real-time visual acquisition and inspection of VLSI boards requires the use of machine vision and artificial intelligence methodologies in a new `frame' for the achievement of better results regarding efficiency, products quality and automated service. In this paper the visual detection and classification of different types of defects on solder joints in PC boards is presented by combining several image processing methods, such as smoothing, segmentation, edge detection, contour extraction and shape analysis. The results of this paper are based on simulated solder defects and a real one.

  8. Point defect relaxation volumes for copper

    International Nuclear Information System (INIS)

    Miller, K.M.

    1979-11-01

    The methods used for the determination of point defect relaxation volumes are discussed and it is shown that a previous interatomic potential derived for copper is inaccurate and results obtained using it are invalid. A new interatomic potential has been produced for copper and a computer simulation of point and planar defects carried out. A vacancy relaxation volume of -0.33 atomic volumes has been found with interstitial values in the range 1.7 to 2.0 atomic volumes. It is shown that these values in current theories of irradiation induced swelling lead to an anomalously high value for dislocation bias compared with that determined experimentally. (author)

  9. Defects and diffusion in semiconductors XIV

    CERN Document Server

    Fisher, David J

    2012-01-01

    This 14th volume in the series covers the latest results in the field of Defects and Diffusion in Semiconductor. The issue also includes some original papers: An Experimental Study of the Thermal Properties of Modified 9Cr-1Mo Steel; Physico-Mechanical Properties of Sintered Iron-Silica Sand Nanoparticle Composites: A Preliminary Study; Defect and Dislocation Density Parameters of 5251 Al Alloy Using Positron Annihilation Lifetime Technique; A Novel Computational Strategy to Enhance the Ability of Elaborate Search by Entire Swarm to Find the Best Solution in Optimization of AMCs; Synthesis and

  10. Keyhole defect production in tubular bone.

    Science.gov (United States)

    Berryman, H E; Gunther, W M

    2000-03-01

    Fracture characteristics, reported primarily for the cranium, are valuable indicators of bullet direction. A bullet striking the vault tangentially produces an irregular opening, termed a "keyhole defect." with the circular portion of the defect being the initial point of impact. Identifying this feature in tubular bone (long bone) can also demonstrate bullet direction and the position of the bone at the time of the shooting. This case study involving a tangential shot (i.e., a keyhole fracture) to the humerus demonstrates some of the same fracture mechanics seen in the cranium.

  11. Agglomeration defects on irradiated carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Cássio Stein Moura

    2012-03-01

    Full Text Available Aligned carbon nanotubes (CNT were irradiated in the longitudinal and perpendicular directions, with low energy carbon and helium ions in order to observe the formation of defects in the atomic structure. Analysis through Raman spectroscopy and scanning electron microscopy indicated bundle rupture and ion track formation on nanotube bundles. Aligned CNT presented a kind of defect comprising ravine formation and tube agglomeration on top of the substrate. The latter structure is possibly caused by static charge accumulation induced by the incoming ions. Fluence plays a role on the short range order. Higher fluence irradiation transforms CNT into amorphous carbon nanowires.

  12. Renal acidification defects in medullary sponge kidney

    DEFF Research Database (Denmark)

    Osther, P J; Hansen, A B; Røhl, H F

    1988-01-01

    Thirteen patients with medullary sponge kidney underwent a short ammonium chloride loading test to investigate their renal acidification capacity. All but 1 presented with a history of recurrent renal calculi and showed bilateral widespread renal medullary calcification on X-ray examination. Nine...... patients had some form of renal acidification defect; 8 had the distal type of renal tubular acidosis, 2 the complete and 6 the incomplete form. One patient had proximal renal tubular acidosis. These findings, which suggest that renal acidification defects play an important role in the pathogenesis...... of renal calculi in medullary sponge kidney, have considerable therapeutic implications....

  13. Photoresponse in graphene induced by defect engineering

    Science.gov (United States)

    Du, Ruxia; Wang, Wenhui; Du, Jianxin; Guo, Xitao; Liu, Er; Bing, Dan; Bai, Jing

    2016-11-01

    We present a photoresponse study on a lateral defect/pristine graphene junction device fabricated by a simple plasma irradiation method. The junction between pristine graphene and plasma-modified graphene was created by controlling the location of Ar+ plasma treatment. We found that a distinct photocurrent was generated at the junction by photocurrent line scanning measurements, and further analysis reveals that the photo-thermoelectric (PTE) effect, instead of the photovoltaic (PV) effect, dominates the photocurrent generation at the interface. Additionally, the obtained results suggest that tuning the defect density could be effective in modulating the optoelectronic performance of junctions in our device.

  14. Defects in Static Elasticity of Quasicrystals

    Directory of Open Access Journals (Sweden)

    Qin Xu

    2017-12-01

    Full Text Available A review on mathematical elasticity of quasicrystals is given. In this review, the focus is on various defects of quasicrystals. Dislocation and crack are two classes of typical topological defects, while their existence has great influence on the mechanical behavior of quasicrystals. The analytic and numerical solutions of dislocations and crack in quasicrystals are the core of the static and dynamic elasticity theory, and this paper gives a comprehensive review on the solutions for dislocations and crack with different configurations in different various important quasicrystalline systems. We review some results in linear elasticity of quasicrystals, referring to different boundary value problems. We also add some new achievements.

  15. Gauge theory and defects in solids

    CERN Document Server

    Edelen, DGB

    2012-01-01

    This new series Mechanics and Physics of Discrete Systems aims to provide a coherent picture of the modern development of discrete physical systems. Each volume will offer an orderly perspective of disciplines such as molecular dynamics, crystal mechanics and/or physics, dislocation, etc. Emphasized in particular are the fundamentals of mechanics and physics that play an essential role in engineering applications.Volume 1, Gauge Theory and Defects in Solids, presents a detailed development of a rational theory of the dynamics of defects and damage in solids. Solutions to field e

  16. Extended cycle hormonal contraception in adolescents.

    Science.gov (United States)

    Sucato, Gina S; Gerschultz, Kelly L

    2005-10-01

    There is increasing interest in the use of extended cycles of hormonal contraception to manage menstrual cycle-related complaints in adolescents and to accommodate the menstrual preferences of patients using hormonal contraception. This review summarizes recent findings related to the use of extended cycles and highlights their relevance to adolescents. Many adolescents would prefer to menstruate less frequently. Among health care providers who prescribe hormonal contraceptives, the majority believe suppressing withdrawal bleeding is well tolerated and prescribe extended cycling regimens to their patients. Shortening or eliminating the hormone-free interval results in greater ovarian suppression and thus may increase contraceptive efficacy. Studies in adult women have not identified changes in metabolic parameters beyond what would be expected from traditional cyclic use. New endometrial biopsy data have found no pathologic changes; most women using an extended cycle had atrophic endometriums. Extended cycling is frequently associated with breakthrough bleeding. In some women, this can be managed with a brief hormone-free interval. Recent findings demonstrate high levels of interest in extended cycling among adolescents and providers, and continue to add to the growing body of literature supporting the safety and improved contraceptive efficacy of extended regimens. Further research is warranted to focus on issues including cancer, thrombotic disease and fertility, and should enroll a sufficient adolescent sample.

  17. The symmetric extendibility of quantum states

    International Nuclear Information System (INIS)

    Nowakowski, Marcin L

    2016-01-01

    Studies on the symmetric extendibility of quantum states have become particularly important in the context of the analysis of one-way quantum measures of entanglement, and the distillability and security of quantum protocols. In this paper we analyze composite systems containing a symmetric extendible part, with particular attention devoted to the one-way security of such systems. Further, we introduce a new one-way entanglement monotone based on the best symmetric approximation of a quantum state and the extendible number of a quantum state. We underpin these results with geometric observations about the structures of multi-party settings which posses substantial symmetric extendible components in their subspaces. The impossibility of reducing the maximal symmetric extendibility by means of the one-way local operations and classical communication method is pointed out on multiple copies. Finally, we state a conjecture linking symmetric extendibility with the one-way distillability and security of all quantum states, analyzing the behavior of a private key in the neighborhood of symmetric extendible states. (paper)

  18. Extended Cognitive System and Epistemic Subject

    Directory of Open Access Journals (Sweden)

    Trybulec Barbara

    2015-03-01

    Full Text Available The concept of an extended cognitive system is central to contemporary studies of cognition. In the paper I analyze the place of the epistemic subject within the extended cognitive system. Is it extended as well? In answering this question I focus on the differences between the first and the second wave of arguments for the extended mind thesis. I argue that the position of Cognitive Integration represented by Richard Menary is much more intuitive and fruitful in analyses of cognition and knowledge than the early argument formulated by Andy Clark and David Chalmers. Cognitive Integration is compatible with virtue epistemology of John Greco’s agent reliabilism. The epistemic subject is constituted by its cognitive character composed of an integrated set of cognitive abilities and processes. Some of these processes are extended, they are a manipulation of external informational structures and, as such, they constitute epistemic practices. Epistemic practices are normative; to conduct them correctly the epistemic subject needs to obey epistemic norms embedded in the cultural context. The epistemic subject is not extended because of the casual coupling with external informational artifacts which extend his mind from inside the head and into the world. Rather, cognitive practices constitute the subject’s mind, they transform his cognitive abilities, and this is what makes the mind and epistemic subject “extended”.

  19. Point defects and defect clusters examined on the basis of some fundamental experiments

    International Nuclear Information System (INIS)

    Zuppiroli, L.

    1975-01-01

    On progressing from the centre of the defect to the surface the theoretical approach to a point defect passes from electronic theories to elastic theory. Experiments by which the point defect can be observed fall into two categories. Those which detect long-range effects: measurement of dimensional variations in the sample; measurement of the mean crystal parameter variation; elastic X-ray scattering near the nodes of the reciprocal lattice (Huang scattering). Those which detect more local effects: low-temperature resistivity measurement; positron capture and annihilation; local scattering far from the reciprocal lattice nodes. Experiments involving both short and long-range effects can always be found. This is the case for example with the dechanneling of α particles by defects. Certain of the experimental methods quoted above apply also to the study of point defect clusters. These methods are illustrated by some of their most striking results which over the last twenty years have refined our knowledge of point defects and defect clusters: length and crystal parameter measurements; diffuse X-ray scattering; low-temperature resistivity measurements; ion emission microscopy; electron microscopy; elastoresistivity [fr

  20. Accurate defect die placement and nuisance defect reduction for reticle die-to-die inspections

    Science.gov (United States)

    Wen, Vincent; Huang, L. R.; Lin, C. J.; Tseng, Y. N.; Huang, W. H.; Tuo, Laurent C.; Wylie, Mark; Chen, Ellison; Wang, Elvik; Glasser, Joshua; Kelkar, Amrish; Wu, David

    2015-10-01

    Die-to-die reticle inspections are among the simplest and most sensitive reticle inspections because of the use of an identical-design neighboring-die for the reference image. However, this inspection mode can have two key disadvantages: (1) The location of the defect is indeterminate because it is unclear to the inspector whether the test or reference image is defective; and (2) nuisance and false defects from mask manufacturing noise and tool optical variation can limit the usable sensitivity. The use of a new sequencing approach for a die-to-die inspection can resolve these issues without any additional scan time, without sacrifice in sensitivity requirement, and with a manageable increase in computation load. In this paper we explore another approach for die-to-die inspections using a new method of defect processing and sequencing. Utilizing die-to-die double arbitration during defect detection has been proven through extensive testing to generate accurate placement of the defect in the correct die to ensure efficient defect disposition at the AIMS step. The use of this method maintained the required inspection sensitivity for mask quality as verified with programmed-defectmask qualification and then further validated with production masks comparing the current inspection approach to the new method. Furthermore, this approach can significantly reduce the total number of defects that need to be reviewed by essentially eliminating the nuisance and false defects that can result from a die-to-die inspection. This "double-win" will significantly reduce the effort in classifying a die-to-die inspection result and will lead to improved cycle times.

  1. Mirror-smooth surfaces and repair of defects in superconducting RF cavities by mechanical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, C. A. [Fermilab; Cooley, L. D. [Fermilab

    2012-11-22

    Mechanical techniques for polishing the inside surface of niobium superconducting radio-frequency (SRF) cavities have been systematically explored. By extending known techniques to fine polishing, mirror-like finishes were produced, with <15 nm RMS (root mean square) roughness over 1 mm2 scan area. This is an order of magnitude less than the typical roughness produced by the electropolishing of niobium cavities. The extended mechanical polishing (XMP) process was applied to several SRF cavities which exhibited equator defects that caused quench at <20 MV m-1 and were not improved by further electropolishing. Cavity optical inspection equipment verified the complete removal of these defects, and minor acid processing, which dulled the mirror finish, restored performance of the defective cells to the high gradients and quality factors measured for adjacent cells when tested with other harmonics. This innate repair feature of XMP could be used to increase manufacturing yield. Excellent superconducting properties resulted after initial process optimization, with quality factor Q of 3 × 1010 and accelerating gradient of 43 MV m-1 being attained for a single-cell TESLA cavity, which are both close to practical limits. Several repaired nine-cell cavities also attained Q > 8 × 109 at 35 MV m-1, which is the specification for the International Linear Collider. Future optimization of the process and pathways for eliminating requirements for acid processing are also discussed.

  2. Defects and Disorder in the Drosophila Eye

    Science.gov (United States)

    Kim, Sangwoo; Carthew, Richard; Hilgenfeldt, Sascha

    Cell division and differentiation tightly control the regular pattern in the normal eye of the Drosophila fruit fly while certain genetic mutations introduce disorder in the form of topological defects. Analyzing data from pupal retinas, we develop a model based on Voronoi construction that explains the defect statistics as a consequence of area variation of individual facets (ommatidia). The analysis reveals a previously unknown systematic long-range area variation that spans the entire eye, with distinct effects on topological disorder compared to local fluctuations. The internal structure of the ommatidia and the stiffness of their interior cells also plays a crucial role in the defect generation. Accurate predictions of the correlation between the area variation and the defect density in both normal and mutant animals are obtained without free parameters. This approach can potentially be applied to cellular systems in many other contexts to identify size-topology correlations near the onset of symmetry breaking. This work has been supported by the NIH (GM098077) and the NSF (Grant No. 1504301).

  3. What Are the Types of Birth Defects?

    Science.gov (United States)

    ... Scientific Counselors (BSC) National Advisory Child Health and Human Development (NACHHD) Council Council Archive National Advisory Board on ... defects, such as missing or misshaped valves Abnormal limbs, such as a ... to the growth and development of the brain and spinal cord Functional or ...

  4. Ultrasound stimulation of mandibular bone defect healing

    NARCIS (Netherlands)

    Schortinghuis, Jurjen

    2004-01-01

    The conclusions of the experimental work presented in this thesis are: 1. Low intensity pulsed ultrasound is not effective in stimulating bone growth into a rat mandibular defect, either with or without the use of osteoconductive membranes. 2. Low intensity pulsed ultrasound does not seem to have an

  5. PROSTHETICS IN CANCER PATIENTS WITH ORBITAL DEFECTS

    Directory of Open Access Journals (Sweden)

    A. A. Kulakov

    2012-01-01

    Full Text Available Orthopedic treatment was performed in 53 patients with postoperative defects in the orbital area during 1969–2012. The developed practical guidelines could improve the cosmetic aspects of ectoprostheses, their fixation, and quality of life in the patients.

  6. 7 CFR 51.1564 - External defects.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false External defects. 51.1564 Section 51.1564 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946...

  7. Genetics Home Reference: abdominal wall defect

    Science.gov (United States)

    ... wall defects managed in a tertiary center in Japan. J Obstet Gynaecol Res. 2009 Feb;35(1): ... Reviewed : August 2016 Published : March 6, 2018 The resources on this site should not be used as a ... Department of Health & Human Services National Institutes of Health National Library of ...

  8. 49 CFR 213.113 - Defective rails.

    Science.gov (United States)

    2010-10-01

    ..., oriented in or near the transverse plane, due to incomplete penetration of the weld metal between the rail ends, lack of fusion between weld and rail end metal, entrainment of slag or sand, under-bead or other shrinkage cracking, or fatigue cracking. Weld defects may originate in the rail head, web, or base, and in...

  9. Parotidectomy with simultaneously reconstruction after surgical defect

    Directory of Open Access Journals (Sweden)

    A. I. Khasanov

    2017-01-01

    Full Text Available Objective: to improve the results of parotidectomy with using the simultaneously reconstruction surgery in the postoperative defects.Background. The radical surgical treatment for salivary gland tumors is parotidectomy with preservation of the facial nerve. However, this treatment leads to postoperative defects and Frey’s syndrome (25 % of cases. Elimination of the above-mentioned disadvantages requires plastic, reconstructive surgery.Materials and methods. In the department of head and neck tumors in the National Cancer Center of Uzbekistan during the period 2015 to 2016 were performed parotidectomy with preservation of the facial nerve and simultaneous retromandibular zone reconstruction with displacing muscle flap in 29 patients. In 25 (86 % patients diagnosed mixed tumor (pleomorphic adenoma and 4 (14 % patients had cancer of parotid gland with the verification of histology.Results. In all of 29 patients were performed parotidectomy with preservation of the facial nerve and the simultaneous reconstruction of retromandibular zone with displacing own bodymuscle flap reduced postoperative complications, which had been revealed before as a defect and hypersensitivity of the retromandibular area.Conclusions. Reconstructive-restorative surgery in patients with tumors in the parotid gland after parotidectomy with saving of the facial nerve is decreased number of cosmetic defect and hypersensitivity. Using the own bodymuscle flap is preferred to patients than allotransplant.

  10. Osteochondral defects in the ankle: why painful?

    NARCIS (Netherlands)

    van Dijk, C. Niek; Reilingh, Mikel L.; Zengerink, Maartje; van Bergen, Christiaan J. A.

    2010-01-01

    Osteochondral defects of the ankle can either heal and remain asymptomatic or progress to deep ankle pain on weight bearing and formation of subchondral bone cysts. The development of a symptomatic OD depends on various factors, including the damage and insufficient repair of the subchondral bone

  11. Treatment of osteochondral defects of the talus

    NARCIS (Netherlands)

    van Bergen, C.J.A.

    2014-01-01

    An osteochondral defect (OCD) of the talus involves the articular cartilage and subchondral bone. It most frequently appears in the second and third decade of life. A traumatic insult, usually ankle sprain, is the most frequent etiologic factor. The typical symptom is persistent or intermittent deep

  12. Point defects in group IV semiconductors

    CERN Document Server

    Pizzini, S

    2017-01-01

    Aim of this book is to focus on the properties of defects in semiconductors of the fourth group under a physico-chemical approach, capable to demonstrate whether the full acknowledgement of their chemical nature could account for several problems encountered in practice or would suggest further experimental or theoretical accomplishments.

  13. The real defect and its nondestructive characterization

    International Nuclear Information System (INIS)

    Licht, H.

    1982-01-01

    Nondestructive test techniques to evaluate defect severity and component degradation are typically based on transmission of energy into the material to be inspected. The capabilities of such techniques are controlled by physical phenomena which generally do not coincide with inspection requirements. This paper reviews several recent developments (mainly in ultrasonic and eddy current testing) which highlight the state of the art

  14. Oil defect detection of electrowetting display

    Science.gov (United States)

    Chiang, Hou-Chi; Tsai, Yu-Hsiang; Yan, Yung-Jhe; Huang, Ting-Wei; Mang, Ou-Yang

    2015-08-01

    In recent years, transparent display is an emerging topic in display technologies. Apply in many fields just like mobile device, shopping or advertising window, and etc. Electrowetting Display (EWD) is one kind of potential transparent display technology advantages of high transmittance, fast response time, high contrast and rich color with pigment based oil system. In mass production process of Electrowetting Display, oil defects should be found by Automated Optical Inspection (AOI) detection system. It is useful in determination of panel defects for quality control. According to the research of our group, we proposed a mechanism of AOI detection system detecting the different kinds of oil defects. This mechanism can detect different kinds of oil defect caused by oil overflow or material deteriorated after oil coating or driving. We had experiment our mechanism with a 6-inch Electrowetting Display panel from ITRI, using an Epson V750 scanner with 1200 dpi resolution. Two AOI algorithms were developed, which were high speed method and high precision method. In high precision method, oil jumping or non-recovered can be detected successfully. This mechanism of AOI detection system can be used to evaluate the oil uniformity in EWD panel process. In the future, our AOI detection system can be used in quality control of panel manufacturing for mass production.

  15. Optical defect modes in chiral liquid crystals

    International Nuclear Information System (INIS)

    Belyakov, V. A.; Semenov, S. V.

    2011-01-01

    An analytic approach to the theory of optical defect modes in chiral liquid crystals (CLCs) is developed. The analytic study is facilitated by the choice of the problem parameters. Specifically, an isotropic layer (with the dielectric susceptibility equal to the average CLC dielectric susceptibility) sandwiched between two CLC layers is studied. The chosen model allows eliminating the polarization mixing and reducing the corresponding equations to the equations for light of diffracting polarization only. The dispersion equation relating the defect mode (DM) frequency to the isotropic layer thickness and an analytic expression for the field distribution in the DM structure are obtained and the corresponding dependences are plotted for some values of the DM structure parameters. Analytic expressions for the transmission and reflection coefficients of the DM structure (CLC-defect layer-CLC) are presented and analyzed for nonabsorbing, absorbing, and amplifying CLCs. The anomalously strong light absorption effect at the DM frequency is revealed. The limit case of infinitely thick CLC layers is considered in detail. It is shown that for distributed feedback lasing in a defect structure, adjusting the lasing frequency to the DM frequency results in a significant decrease in the lasing threshold. The DM dispersion equations are solved numerically for typical values of the relevant parameters. Our approach helps clarify the physics of the optical DMs in CLCs and completely agrees with the corresponding results of the previous numerical investigations.

  16. Complement defects in patients with chronic rhinosinusitis

    DEFF Research Database (Denmark)

    Gaunsbaek, Maria Quisgaard; Lange, Bibi; Kjeldsen, Anette D

    2012-01-01

    The complement system is an important part of our immune system, and complement defects lead generally to increased susceptibility to infections and autoimmune diseases. We have studied the role of complement activity in relation with chronic rhinosinusitis (CRS), and more specifically studied wh...

  17. Importance of packing in spiral defect chaos

    Indian Academy of Sciences (India)

    We develop two measures to characterize the geometry of patterns exhibited by the state of spiral defect chaos, a weakly turbulent regime of Rayleigh-Bénard convection. These describe the packing of contiguous stripes within the pattern by quantifying their length and nearest-neighbor distributions. The distributions ...

  18. Partial Auricular Defects; Classification & Reconstruction Guideline ...

    African Journals Online (AJOL)

    Background: The protruding position of the auricle makes it susceptible to trauma and results in a wide variety of auricular defects .Therefore many techniques had been developed for reconstruction .To select a proper technique may represent a challenge to the occasional otoplastic surgeon. This article proposes a ...

  19. Living with a Congenital Heart Defect

    Science.gov (United States)

    ... Living With Heart Defects Data & Statistics Tracking & Research Articles & Key Findings Free Materials Multimedia and Tools Links to Other Websites ... was followed by a year of a salt-free diet and no school. Having ... I opted to become a software engineer, and took up a career in information ...

  20. Multiple congenital defects in a newborn foal

    Directory of Open Access Journals (Sweden)

    J.F. Silva

    2014-12-01

    Full Text Available A case of multiple congenital defects in a newborn foal is reported. The animal showed hypoplasia of the left pelvic limb bones, uterus unicornis, congenital diaphragmatic hernia, and unilateral renal and ureteral agenesis. This report includes the macroscopic and microscopic lesions observed in the case.