WorldWideScience

Sample records for electron induced break-up

  1. Electron induced break-up of helium. Benchmark experiments on a dynamical four-body Coulomb system

    Energy Technology Data Exchange (ETDEWEB)

    Duerr, M.

    2006-07-05

    This work presents an experimental study of fragmentation of helium by electron impact, in which absolute fully differential cross sections for single ionization, ionization-excitation and double ionization were determined. By applying a charged-particle imaging technique, the so-called 'reaction microscope', a large fraction of the final-state momentum space is covered, and the major limitations of previous experimental methods applied in this field could be overcome. Decisive modifications of the previous reaction microscope were undertaken, the most important one being the arrangement of the projectile beam parallel to the imaging-fields. For single ionization on helium an enhanced electron emission outside the projectile scattering plane is observed at both considered impact energies (102 eV and 1 keV), which is similar to the result found for ion-impact (M. Schulz et al., Nature (London) 422, 48 (2003)). The angle resolved cross sections obtained for double ionization at 105 eV impact energy reveal, that the process is dominated by the mutual repulsion of the three final-state continuum electrons. However, signatures of more complex dynamics are also observed. The data provide an ultimate benchmark for recently developed theories treating the dynamical three- and four-body Coulomb problem. (orig.)

  2. Modelling wave-induced sea ice break-up in the marginal ice zone.

    Science.gov (United States)

    Montiel, F; Squire, V A

    2017-10-01

    A model of ice floe break-up under ocean wave forcing in the marginal ice zone (MIZ) is proposed to investigate how floe size distribution (FSD) evolves under repeated wave break-up events. A three-dimensional linear model of ocean wave scattering by a finite array of compliant circular ice floes is coupled to a flexural failure model, which breaks a floe into two floes provided the two-dimensional stress field satisfies a break-up criterion. A closed-feedback loop algorithm is devised, which (i) solves the wave-scattering problem for a given FSD under time-harmonic plane wave forcing, (ii) computes the stress field in all the floes, (iii) fractures the floes satisfying the break-up criterion, and (iv) generates an updated FSD, initializing the geometry for the next iteration of the loop. The FSD after 50 break-up events is unimodal and near normal, or bimodal, suggesting waves alone do not govern the power law observed in some field studies. Multiple scattering is found to enhance break-up for long waves and thin ice, but to reduce break-up for short waves and thick ice. A break-up front marches forward in the latter regime, as wave-induced fracture weakens the ice cover, allowing waves to travel deeper into the MIZ.

  3. Coulomb- and nuclear-induced break-up of halo nuclei at bombarding energies around the Coulomb barrier

    Energy Technology Data Exchange (ETDEWEB)

    Dasso, C.H. [Niels Bohr Inst., Copenhagen (Denmark); Guisado, J.L. [Niels Bohr Inst., Copenhagen (Denmark); Lenzi, S.M. [Niels Bohr Inst., Copenhagen (Denmark)]|[Padua Univ. (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Padua (Italy); Vitturi, A. [Padua Univ. (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Padua (Italy)

    1996-02-05

    We investigate the relative importance of the Coulomb and nuclear fields to induce the break-up of neutron-rich nuclei such as {sup 11}Li at energies close to the Coulomb barrier. We assume that the mechanism that leads to the separation is the excitation of a low-lying dipole mode in which the weakly-bound neutron halo performs a collective oscillation against the residual nuclear core. To this end we exploit semiclassical prescriptions that are adequate to calculate not only the average break-up probabilities but also to estimate the size of fluctuations about the quantal expectation values. Possible outcomes are explored as a function of both bombarding energy and impact parameter. Consequences of the couplings for elastic scattering and fusion processes are also discussed. (orig.).

  4. Coal-water slurry sprays from an electronically controlled accumulator fuel injection system: Break-up distances and times

    Science.gov (United States)

    Caton, J. A.; Payne, S. E.; Terracina, D. P.; Kihm, K. D.

    Experiments have been completed to characterize coal-water slurry sprays from an electronically-controlled accumulator fuel injection system of a diesel engine. The sprays were injected into a pressurized chamber equipped with windows. High speed movies, fuel pressures, and needle lifts were obtained as a function of time, orifice diameter, coal loading, gas density in the chamber, and accumulator fuel pressure. For the base conditions (50% by mass coal loading, 0.4 mm diameter nozzle hole, coal-water slurry pressure of 82 MPa (12,000 psi), and a chamber density of 25 kg/m(exp 3)), the break-up time was 0.30 ms. An empirical correlation for spray tip penetration, break-up time, and initial jet velocity was developed. For the conditions of this study, the spray tip penetration and initial jet velocity were 15% greater for coal-water slurry than for diesel fuel or water. Results of this study and the correlation are specific to the tested coal-water slurry and are not general for other coal-water slurry fuels.

  5. Flocculation and floc break-up related to tidally induced turbulent shear in a low-turbidity, microtidal estuary

    DEFF Research Database (Denmark)

    Markussen, Thor Nygaard; Andersen, Thorbjørn Joest

    2014-01-01

    mean threshold diameter of 50–60 μm present at high turbulent shear flocculated to form fragile macroflocs with sizes of several hundred microns and mean diameters above 80 μm around slack water periods. A hysteresis in floc break-up and flocculation was found at high water slack (HWS), as flocs formed...... at a root mean square velocity gradient (G) around 1 s− 1 were not broken up until the shear reached G > 4 s− 1. As an effect, the flocculation time (time for flocculation from constituent microflocs to fragile macroflocs) was roughly 100 min while the equivalent floc break-up time was roughly 200 min...

  6. Botulinum hemagglutinin-mediated in situ break-up of human induced pluripotent stem cell aggregates for high-density suspension culture.

    Science.gov (United States)

    Nath, Suman C; Tokura, Tomohiro; Kim, Mee-Hae; Kino-Oka, Masahiro

    2018-04-01

    Large numbers of human induced pluripotent stem cells (hiPSCs) are required for making stable cell bank. Although suspension culture yields high cell numbers, there remain unresolved challenges for obtaining high-density of hiPSCs because large size aggregates exhibit low growth rates. Here, we established a simple method for hiPSC aggregate break-up using botulinum hemagglutinin (HA), which specifically bound with E-cadherin and disrupted cell-cell connections in hiPSC aggregates. HA showed temporary activity for disrupting the E-cadherin-mediated cell-cell connections to facilitate the break-up of aggregates into small sizes only 9 hr after HA addition. The transportation of HA into the aggregates was mediated by transcellular and paracellular way after HA addition to the culture medium. hiPSC aggregates broken up by HA showed a higher number of live cells, higher cell density, and higher expansion fold compared to those of aggregates dissociated with enzymatic digestion. Moreover, a maximum cell density of 4.5 ± 0.2 × 10 6 cells ml -1 was obtained by aggregate break-up into small ones, which was three times higher than that with the conventional culture without aggregate break-up. Therefore, the temporary activity of HA for disrupting E-cadherin-mediated cell-cell connection was key to establishing a simple in situ method for hiPSC aggregate break-up in bioreactors, leading to high cell density in suspension culture. © 2017 Wiley Periodicals, Inc.

  7. Parental Break-Ups and Stress

    DEFF Research Database (Denmark)

    Dissing, Agnete S.; Dich, Nadya; Nybo Andersen, Anne-Marie

    2017-01-01

    Background: Parental break-up is wide spread, and the effects of parental break-up on children’s well-being are known. The evidence regarding child age at break-up and subsequent family arrangements is inconclusive. Aim: to estimate the effects of parental break-up on stress in pre-adolescent chi......Background: Parental break-up is wide spread, and the effects of parental break-up on children’s well-being are known. The evidence regarding child age at break-up and subsequent family arrangements is inconclusive. Aim: to estimate the effects of parental break-up on stress in pre......-adolescent children with a specific focus on age at break-up and post-breakup family arrangements. Methods: We used data from the Danish National Birth Cohort. Participants included 44 509 children followed from birth to age 11. Stress was self-reported by children at age 11, when the children also reported...... on parental break-up and post break-up family arrangements. Results: Twenty-one percent of the children had experienced a parental break-up at age 11, and those who had experienced parental break-up showed a higher risk of stress (OR:1.72, 95%CI:1.55;1.91) regardless of the child’s age at break-up. Children...

  8. Firm break-up and performance

    Czech Academy of Sciences Publication Activity Database

    Kočenda, Evžen; Hanousek, Jan

    2012-01-01

    Roč. 13, č. 2 (2012), s. 121-143 ISSN 1435-6104 R&D Projects: GA ČR GA402/09/1595 Institutional support: PRVOUK-P23 Keywords : break-up of firms * corporate performance * ownership changes Subject RIV: AH - Economics Impact factor: 0.588, year: 2012

  9. Plume-induced continental break-up from Red Sea to Lake Malawi: 3D numerical models of the East African Rift System

    Science.gov (United States)

    Koptev, Alexander; Burov, Evgueni; Calais, Eric; Leroy, Sylvie; Gerya, Taras; Cloetingh, Sierd; Guillou-Frottier, Laurent

    2017-04-01

    We use numerical thermo-mechanical experiments in order to analyze the role of active mantle plume, far-field tectonic stresses and pre-existing lithospheric heterogeneities in structural development of the East African Rift system (EARS). It is commonly assumed that the Cenozoic rifts have avoided the cratons and follow the mobile belts which serve as the weakest pathways within the non-uniform material structured during pre-rift stages. Structural control of the pre-existing heterogeneities within the Proterozoic belts at the scale of individual faults or rifts has been demonstrated as well. However, the results of our numerical experiments show that the formation of two rift zones on opposite sides of a thick lithosphere segment can be explained without appealing to pre-imposed heterogeneities at the crustal level. These models have provided a unified physical framework to understand the development of the Eastern branch, the Western branch and its southern prolongation by the Malawi rift around thicker lithosphere of the Tanzanian and Bangweulu cratons as a result of the interaction between pre-stressed continental lithosphere and single mantle plume anomaly corresponding to the Kenyan plume. The second series of experiments has been designed in order to investigate northern segment of the EARS where Afro-Arabian plate separation is supposed to be related with the impact of Afar mantle plume. We demonstrate that whereas relatively simple linear rift structures are preferred in case of uni-directional extension, more complex rifting patterns combining one or several ridge-ridge-ridge triple junctions can form in response to bi-directional extensional far-field stresses. In particular, our models suggest that Afar triple junction represents an end-member mode of plume-induced bi-directional rifting combining asymmetrical northward traction and symmetrical EW extension of similar magnitudes. The presence of pre-existing linear weak zones appears to be not

  10. Age of Seychelles India break-up

    Science.gov (United States)

    Collier, J. S.; Sansom, V.; Ishizuka, O.; Taylor, R. N.; Minshull, T. A.; Whitmarsh, R. B.

    2008-07-01

    Many continental flood basalt provinces are spatially and temporally linked with continental break-up. Establishing the relative timing of the two events is a key step in determining their causal relationship. Here we investigate the example of the Deccan Traps and the separation of India and the Seychelles. Whilst there has been a growing consensus as to the age of the main phase of the Deccan emplacement (65.5 ± 1 Ma, chron 29r), the age of the rifting has remained unclear. We resolve this issue through detailed seafloor magnetic anomaly modeling (supported by wide-angle and reflection seismic results) of the north Seychelles and conjugate Laxmi Ridge/Gop Rift margins, and geochemistry and 40Ar/ 39Ar geochronology of rocks from the north Seychelles margin. We show that syn-rift volcanics offshore the Seychelles Islands in the form of seaward-dipping reflectors were most likely erupted during chron 28n, and the first organized seafloor spreading at the Carlsberg Ridge also initiated during this chron at 63.4 Ma. The severing of the Seychelles occurred by a south-eastward ridge propagation that was completed by the start of chron 27n (~ 62 Ma). A brief, pre-28r phase of seafloor spreading occurred in the Gop Rift, possibly as early as 31r-32n (~ 71 Ma). Initial extension at the margin therefore preceded or was contemporaneous with the Deccan emplacement, and separation of the Seychelles was achieved less than 3.5 Ma afterwards. This is the shortest time interval between flood basalt emplacement and break-up yet reported for any continental flood basalt-rifted margin pair. A contributing factor to the apparently short interval in the Deccan case may be that rifting occurred by a ridge jump into already thinned continental lithosphere. However, we conclude that external plate-boundary forces, rather than the impact of a mantle plume, were largely responsible for the rifting of the Seychelles from India.

  11. 24 CFR 982.315 - Family break-up.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Family break-up. 982.315 Section... SECTION 8 TENANT BASED ASSISTANCE: HOUSING CHOICE VOUCHER PROGRAM Leasing a Unit § 982.315 Family break-up... assistance in the program if the family breaks up. The PHA administrative plan must state PHA policies on how...

  12. Tear film break-up time in rabbits.

    Science.gov (United States)

    Wei, Xiaojia E; Markoulli, Maria; Zhao, Zhenjun; Willcox, Mark D P

    2013-01-01

    Rabbits have a longer inter-blink time (approximately 10 minutes) compared with humans (five to eight seconds), suggesting that rabbits have a much more stable tear film. Using fluorescein, the tear break-up time of rabbits has been reported to be similar to that of humans. This study set out to measure the tear break-up time in rabbits using non-invasive methods and to establish the pattern of tear break-up compared to humans. The tear break-up time was measured and the pattern of tear break-up was observed in six New Zealand White rabbits on two separate occasions using both the Keeler Tearscope-plus(TM) and a slitlamp biomicroscope. The mean rabbit tear break-up time was 29.8 ± 3.4 (SD) minutes. This contrasts with the reports of human tear break-up time of eight to 30 seconds. The tear breaking spread very slowly and was often restricted to the area of the initial break. Rabbit tears have a significantly higher tear break-up time than humans and this aligns with previously demonstrated differences in inter-blink time between rabbits and humans. Understanding the underlying mechanisms of tear stability may lead to novel ways of increasing human tear film stability. © 2012 The Authors. Clinical and Experimental Optometry © 2012 Optometrists Association Australia.

  13. 11Li structural information from inclusive break-up measurements

    Directory of Open Access Journals (Sweden)

    Fernández-García J. P.

    2015-01-01

    Full Text Available Structure information of 11Li halo nucleus has been obtained from the inclusive break-up measurements of the 11Li+208Pb reactions at energies around the Coulomb barrier (Elab = 24.3 and 29.8 MeV. The effective break-up energy and the slope of B(E1 distribution close to the threshold have been extracted from the experimental data.

  14. Volcanic passive margins: another way to break up continents.

    Science.gov (United States)

    Geoffroy, L; Burov, E B; Werner, P

    2015-10-07

    Two major types of passive margins are recognized, i.e. volcanic and non-volcanic, without proposing distinctive mechanisms for their formation. Volcanic passive margins are associated with the extrusion and intrusion of large volumes of magma, predominantly mafic, and represent distinctive features of Larges Igneous Provinces, in which regional fissural volcanism predates localized syn-magmatic break-up of the lithosphere. In contrast with non-volcanic margins, continentward-dipping detachment faults accommodate crustal necking at both conjugate volcanic margins. These faults root on a two-layer deformed ductile crust that appears to be partly of igneous nature. This lower crust is exhumed up to the bottom of the syn-extension extrusives at the outer parts of the margin. Our numerical modelling suggests that strengthening of deep continental crust during early magmatic stages provokes a divergent flow of the ductile lithosphere away from a central continental block, which becomes thinner with time due to the flow-induced mechanical erosion acting at its base. Crustal-scale faults dipping continentward are rooted over this flowing material, thus isolating micro-continents within the future oceanic domain. Pure-shear type deformation affects the bulk lithosphere at VPMs until continental breakup, and the geometry of the margin is closely related to the dynamics of an active and melting mantle.

  15. Breaking up with Deleuze: Desire and Valuing the Irreconcilable

    Science.gov (United States)

    Tuck, Eve

    2010-01-01

    In this article, Eve Tuck grapples with Gilles Deleuze's conceptualization of desire, finding it simultaneously generative and unsatisfying. Recognizing that Deleuze will not "say" what Tuck wants him to say about desire--that it is smart, and constitutes expertise--Tuck reasons that there is only one thing she can do: break up with Deleuze. The…

  16. Systematics in break-up fusion reactions at low energies

    International Nuclear Information System (INIS)

    Singh, B.P.

    2017-01-01

    The reaction mechanism of heavy-ion interactions at low projectile energies is still not well understood. Both the fusion as well as break-up fusion of projectile have been observed at these energies. In the break-up fusion, also referred to as the incomplete fusion (ICF), a part of the incident ion fuses with the target nucleus while the remnant moves forward with the same velocity as that of projectile. Several models have been proposed, however, none of them could reproduce the data on ICF process. In order to study the break-up fusion reactions and to study its influence on various entrance channel parameters, several experiments have been carried out using pelletron accelerator facility at the Inter University Accelerator Centre (IUAC), New Delhi. The analysis of data has indicated significant break-up fusion contributions at energies ≈ 4-7 MeV/nucleon. Important systematic for incomplete or breakup fusion reactions have been observed and will be presented. (author)

  17. Breaking Up is Hard to Do… Why do long-term couples decide to break-up?

    Czech Academy of Sciences Publication Activity Database

    Vohlídalová, Marta

    2009-01-01

    Roč. 7, 7-8 (2009), s. 5-7 ISSN 1214-1720 Grant - others:GA UK(CZ) 9864/2009 Institutional research plan: CEZ:AV0Z70280505 Keywords : family * divorce s * unmarried cohabitation break-ups Subject RIV: AO - Sociology, Demography http://www.socioweb.cz

  18. Molecular physics: Breaking up is hard to do

    Science.gov (United States)

    Slaughter, Daniel S.; Rescigno, Thomas N.

    2018-02-01

    Dissociating hydrogen gas seems like it should be as easy as pulling apart two identical atoms. But resonant electron-impact experiments reveal that quantum interference induces a fundamental asymmetry in the process.

  19. Breaking up Romantic Relationships: Costs Experienced and Coping Strategies Deployed

    OpenAIRE

    Carin Perilloux; David M. Buss

    2008-01-01

    This study examined differences between men and women, and between individuals experiencing rejection (Rejectees) and individuals doing the rejecting (Rejectors) in romantic relationship break-ups. We tested fourteen evolution-based predictions about romantic breakups using data from 193 participants; ten received support. Women more than men, for example, experienced costly sequelae such as the loss of a mate's physical protection and harmful post-breakup stalking by the ex-partner. Both men...

  20. Breaking up sitting time after stroke (BUST-Stroke).

    Science.gov (United States)

    Janssen, Heidi; Dunstan, David W; Bernhardt, Julie; Walker, Frederick R; Patterson, Amanda; Callister, Robin; Dunn, Ashlee; Spratt, Neil J; English, Coralie

    2017-06-01

    Rationale Prolonged sitting is associated with an increased risk of cardiovascular and all-cause mortality and morbidity. The metabolic and cardiovascular effects of breaking up sitting time in people with stroke are unknown. Aims and hypotheses To determine the (i) metabolic and cardiovascular effects and (ii) safety and feasibility of an experimental protocol to break up uninterrupted sitting in people with stroke. We hypothesize that activity breaks will attenuate the effects of uninterrupted sitting on glucose and insulin metabolism, blood pressure, lipid profiles, and plasma fibrinogen and that it will be both safe and feasible. Sample size estimate Based on previous estimates of population variability (SD 1% glucose and 30% insulin), 19 paired observations (i.e. participants) will achieve a power of 0.9 to detect a difference of 0.8% in glucose and 24% in insulin area under the curve (two-tailed testing, α = 0.05). Methods and design People with stroke will complete three experimental conditions one week apart in randomized order: (a) uninterrupted sitting, (b) prolonged sitting with intermittent walking, and (c) prolonged sitting with intermittent standing exercises. Serial blood samples will be collected and blood pressure measured at 30 min intervals for 8 h. Study outcomes Primary outcome will be postprandial glucose and insulin responses. Secondary outcomes will include fibrinogen concentrations, blood pressure, and adverse events and protocol feasibility. Discussion This is the first important step in determining the cardiovascular effects of breaking up sitting time after stroke. Findings will guide future studies testing behavioral strategies to reduce sitting time for the purpose of lowering recurrent stroke risk.

  1. Two-Branch Break-up Systems by a Single Mantle Plume: Insights from Numerical Modeling

    Science.gov (United States)

    Beniest, A.; Koptev, A.; Leroy, S.; Sassi, W.; Guichet, X.

    2017-10-01

    Thermomechanical modeling of plume-induced continental break-up reveals that the initial location of a mantle anomaly relative to a lithosphere inhomogeneity has a major impact on the geometry and timing of a rift-to-spreading system. Models with a warmer Moho temperature are more likely to result in "plume-centered" mode, where the rift and subsequent spreading axis grow directly above the plume. Models with weak far-field forcing are inclined to develop a "structural-inherited" mode, with lithosphere deformation localized at the lateral lithospheric boundary. Models of a third group cultivate two break-up branches (both "plume-centered" and "structural inherited") that form consecutively with a few million years delay. With our experimental setup, this break-up mode is sensitive to relatively small lateral variations of the initial anomaly position. We argue that one single mantle anomaly can be responsible for nonsimultaneous initiation and development of two rift-to-spreading systems in a lithosphere with a lateral strength contrast.

  2. Aerosol cluster impact and break-up: model and implementation

    International Nuclear Information System (INIS)

    Lechman, Jeremy B.

    2010-01-01

    In this report a model for simulating aerosol cluster impact with rigid walls is presented. The model is based on JKR adhesion theory and is implemented as an enhancement to the granular (DEM) package within the LAMMPS code. The theory behind the model is outlined and preliminary results are shown. Modeling the interactions of small particles is relevant to a number of applications (e.g., soils, powders, colloidal suspensions, etc.). Modeling the behavior of aerosol particles during agglomeration and cluster dynamics upon impact with a wall is of particular interest. In this report we describe preliminary efforts to develop and implement physical models for aerosol particle interactions. Future work will consist of deploying these models to simulate aerosol cluster behavior upon impact with a rigid wall for the purpose of developing relationships for impact speed and probability of stick/bounce/break-up as well as to assess the distribution of cluster sizes if break-up occurs. These relationships will be developed consistent with the need for inputs into system-level codes. Section 2 gives background and details on the physical model as well as implementations issues. Section 3 presents some preliminary results which lead to discussion in Section 4 of future plans.

  3. Study of projectile break-up process at intermediate energies

    International Nuclear Information System (INIS)

    Kumar, Harish; Parashari, Siddharth; Tali, Suhail A.

    2016-01-01

    The projectile break-up reactions are explained in terms of incomplete fusion or massive transfer reactions leading to the formation of composite system with less mass, charge and excitation energy, as compared to the complete fusion (CF) process. Since, the existing theoretical models are not applicable to reproduce the experimentally measured ICF, data satisfactory below 10 MeV/nucleon energies; thereby the study of the role of the entrance channel parameters in the fusion reactions is still a relevant problem in establishing the explicit inference regarding the influence of ICF on CF at 4-7 MeV/nucleon energies. Recently reported some studies have also shown that alpha Q-value is also an important parameter which affects the onset of ICF and conflict with the suggestion of Morgenstern et al. Keeping in view the recent aspects, to provide more strength to the aspect of projectile-target mass-asymmetry effect, role of non α-cluster projectile over α-cluster projectile, the present work has been carried out which will be useful to understand a clearer picture about the conflict between mass-asymmetry and projectile structure effect on break-up fusion process. As such, excitation function measurement of residues produced in 13 C + 175 Lu system has been carried out in a series of experiments of comparative study using α-cluster as well as non α-cluster projectiles with deformed heavier target nuclei at lower projectile energies ≈ 4-7 MeV/nucleon

  4. Break-up fragment topology in statistical multifragmentation models

    International Nuclear Information System (INIS)

    Raduta, Ad. R.

    2009-01-01

    Break-up fragmentation patterns together with kinetic and configurational energy fluctuations are investigated in the framework of a microcanonical model with fragment degrees of freedom over a broad excitation energy range. As long as fragment partitioning is approximately preserved, energy fluctuations are found to be rather insensitive to both the way in which the freeze-out volume is constrained and the trajectory followed by the system in the excitation-energy-freeze-out volume space. Due to hard-core repulsion, the freeze-out volume is found to be populated nonuniformly, its highly depleted core giving the source a bubble-like structure. The most probable localization of the largest fragments in the freeze-out volume may be inferred experimentally from their kinematic properties, largely dictated by Coulomb repulsion.

  5. Different modes of continental break-up triggered by a sole mantle plume: a 2D and 3D numerical study

    Science.gov (United States)

    Beniest, Anouk; Koptev, Alexander; Leroy, Sylvie; Burov, Evgueni

    2017-04-01

    We used 2D and 3D numerical models to investigate the impact of a single mantle plume on continental rifting and breakup processes. We varied the thermo-rheological structure of the continental lithosphere, its geometry and the initial plume position. Based on the results of our 2D experiments, three continental break-up modes can be distinguished: A) 'central' continental break-up, the break-up center is located directly above the original mantle anomaly position, B) 'shifted' break-up, the break-up center is 50 to 200 km displaced from the initial plume location and C) 'distant' break-up, due to convection and/or slab-subduction/delamination, the break-up center is considerably shifted (300 to 800 km) from the primary plume position. Our 3D model, with a laterally homogeneous initial setup also results in continental break-up with the axis of continental break-up hundreds of kilometers shifted from the original plume location. The model results show that the classical, 'central' view of mantle plume induced continental break-up is not the only mode of break-up. When considering a diversity of break-up styles, it is possible to explain a variety of observed geophysical and geological features. For example, the mantle material glued to the base of the lithosphere at shallower depths corresponds geometrically and location-wise to high-velocity/high-density bodies observed on seismic data below the thinned continental lithosphere and the transition zone of the South Atlantic domain. During migration, products of partial melting of the mantle material can move vertically to (shallow) lower crustal levels. They might resemble high density bodies observed at lower crustal levels inside continental crust with similar geometries observed with gravity modelling. Also, topographic variation form in the very early stages of rifting on the first impingement of upwelled plume material. These variations remain visible, as the final position of the spreading center is shifted

  6. Breaking up Romantic Relationships: Costs Experienced and Coping Strategies Deployed

    Directory of Open Access Journals (Sweden)

    Carin Perilloux

    2008-01-01

    Full Text Available This study examined differences between men and women, and between individuals experiencing rejection (Rejectees and individuals doing the rejecting (Rejectors in romantic relationship break-ups. We tested fourteen evolution-based predictions about romantic breakups using data from 193 participants; ten received support. Women more than men, for example, experienced costly sequelae such as the loss of a mate's physical protection and harmful post-breakup stalking by the ex-partner. Both men and women who were rejected, compared with those who did the rejecting, experienced more depression, loss of self-esteem, and rumination. Rejectors, on the other hand, experienced the reputational cost of being perceived by others as cruel. Exploratory data analyses revealed that women more than men reported experiencing negative emotions after a breakup, particularly feeling sad, confused, and scared. Both sexes used an array of strategies to cope with the breakup, ranging from high base-rate strategies such as discussing the breakup with friends to low base-rate strategies such as threatening suicide. The largest sex difference in coping strategies centered on the act of shopping, used by women Rejectors as well as women Rejectees, likely a strategy of appearance enhancement prior to reentering the mating market. Discussion focuses on the adaptive significance of sex differences and individual differences based on rejection status.

  7. Bubble Rise and Break-Up in Volcanic Conduits

    Science.gov (United States)

    Soldati, A.; Cashman, K. V.; Rust, A.; Rosi, M.

    2013-12-01

    The continual passive degassing occurring at open-vent mafic volcanoes is often punctuated by bursts of active degassing. The latter are generally thought to be the result of slug flow: large, conduit-filling bubbles periodically rising up the feeder conduit and bursting at the magma-air interface. Existing models of volcanic degassing systems make the simplifying assumption that the conduit is cylindrical; however, while this may be true at shallow levels, a flaring probably connects it to a dyke-like geometry at depth. The overall goal of this research is to assess the influence of conduit geometry on the speed and stability of bubbles rising in open-vent systems, and ultimately to devise a model to infer conduit shape from emerging bubbles size. In order to do that an analogue experimental approach was used. All of the experiments were two-phase (melt+volatiles); the analogue materials of choice were golden syrup-water mixtures ranging in viscosity from 10-1 to 104 Pa*s and air. Two experimental apparatuses were used: a bi-dimensional and a tri-dimensional one. The bi-dimensional set-up is a cell made of two flat transparent PVC plates (44x23cm) 10mm or 5mm apart (the front one having a hole at the bottom permitting bubble injection) containing a variety of parallelepipeds apt to outline different plumbing system geometries. The tri-dimensional one consists of a cylindrical tube (r=1,5cm; l=7cm) allowing bubble injection through the bottom rubber tap and terminating into a square tank (l=22cm). Results indicate that conduit geometry directly controls the slug rise velocity and the surrounding liquid descending speed, which in turn control the slug stability. Small enough bubbles simply deform as they go through the flaring, while bigger ones split into two daughter bubbles. A regime diagram has been constructed, illustrating the bubble break-up threshold dependence on the flare geometry and initial slug size, the two main controlling factors. The phenomenon of

  8. Black holes will break up solitons and white holes may destroy them

    International Nuclear Information System (INIS)

    Akbar, Fiki T.; Gunara, Bobby E.; Susanto, Hadi

    2017-01-01

    Highlights: • What happens if a soliton collides with a black or white hole? • Solitons can pass through black hole horizons, but they will break up into several solitons after the collision. • In the interaction with a white hole horizon, solitons either pass through the horizon or will be destroyed by it. - Abstract: We consider a quantum analogue of black holes and white holes using Bose–Einstein condensates. The model is described by the nonlinear Schrödinger equation with a ‘stream flow’ potential, that induces a spatial translation to standing waves. We then mainly consider the dynamics of dark solitons in a black hole or white hole flow analogue and their interactions with the event horizon. A reduced equation describing the position of the dark solitons was obtained using variational method. Through numerical computations and comparisons with the analytical approximation we show that solitons can pass through black hole horizons even though they will break up into several solitons after the collision. In the interaction with a white hole horizon, we show that solitons either pass through the horizon or will be destroyed by it.

  9. Black holes will break up solitons and white holes may destroy them

    Energy Technology Data Exchange (ETDEWEB)

    Akbar, Fiki T., E-mail: ftakbar@fi.itb.ac.id [Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10, Bandung, 40132 (Indonesia); Gunara, Bobby E., E-mail: bobby@fi.itb.ac.id [Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10, Bandung, 40132 (Indonesia); Susanto, Hadi, E-mail: hsusanto@essex.ac.uk [Department of Mathematical Sciences, University of Essex, Colchester, CO4 3SQ (United Kingdom)

    2017-06-15

    Highlights: • What happens if a soliton collides with a black or white hole? • Solitons can pass through black hole horizons, but they will break up into several solitons after the collision. • In the interaction with a white hole horizon, solitons either pass through the horizon or will be destroyed by it. - Abstract: We consider a quantum analogue of black holes and white holes using Bose–Einstein condensates. The model is described by the nonlinear Schrödinger equation with a ‘stream flow’ potential, that induces a spatial translation to standing waves. We then mainly consider the dynamics of dark solitons in a black hole or white hole flow analogue and their interactions with the event horizon. A reduced equation describing the position of the dark solitons was obtained using variational method. Through numerical computations and comparisons with the analytical approximation we show that solitons can pass through black hole horizons even though they will break up into several solitons after the collision. In the interaction with a white hole horizon, we show that solitons either pass through the horizon or will be destroyed by it.

  10. Squeezing bio-capsules into a constriction: deformation till break-up.

    Science.gov (United States)

    Le Goff, Anne; Kaoui, Badr; Kurzawa, Gaetan; Haszon, Boglárka; Salsac, Anne-Virginie

    2017-10-25

    We study experimentally the deformation and break-up of liquid-filled capsules trapped at an axisymmetric step constriction, and subjected to increasing pressure drops. We considered biological (trout fish eggs) and bioartificial (made of ovalbumin and alginate) ones, with the objective to characterize the transition to break-up. We find that both capsule populations behave as a brittle material. They do not exhibit any plastic deformation prior to break-up. Moreover critical pressure drop exhibits a stochastic behavior as known for the fracture of disordered media. The break-up probability follows a three-parameter Weibull distribution, from which one can deduce the capsule rupture characteristics.

  11. Amphiphilic nanoparticles suppress droplet break-up in a concentrated emulsion flowing through a narrow constriction.

    Science.gov (United States)

    Gai, Ya; Kim, Minkyu; Pan, Ming; Tang, Sindy K Y

    2017-05-01

    This paper describes the break-up behavior of a concentrated emulsion comprising drops stabilized by amphiphilic silica nanoparticles flowing in a tapered microchannel. Such geometry is often used in serial droplet interrogation and sorting processes in droplet microfluidics applications. When exposed to high viscous stresses, drops can undergo break-up and compromise their physical integrity. As these drops are used as micro-reactors, such compromise leads to a loss in the accuracy of droplet-based assays. Here, we show droplet break-up is suppressed by replacing the fluoro-surfactant similar to the one commonly used in current droplet microfluidics applications with amphiphilic nanoparticles as droplet stabilizer. We identify parameters that influence the break-up of these drops and demonstrate that break-up probability increases with increasing capillary number and confinement, decreasing nanoparticle size, and is insensitive to viscosity ratio within the range tested. Practically, our results reveal two key advantages of nanoparticles with direct applications to droplet microfluidics. First, replacing surfactants with nanoparticles suppresses break-up and increases the throughput of the serial interrogation process to 3 times higher than that in surfactant system under similar flow conditions. Second, the insensitivity of break-up to droplet viscosity makes it possible to process samples having different composition and viscosities without having to change the channel and droplet geometry in order to maintain the same degree of break-up and corresponding assay accuracy.

  12. The Effects of Breaking up Prolonged Sitting Time

    DEFF Research Database (Denmark)

    Benatti, Fabiana Braga; Ried-Larsen, Mathias

    2015-01-01

    on the electronic databases PUBMED and SCOPUS was independently conducted by two researchers. Only prospective intervention studies (controlled and uncontrolled) evaluating the effects of explicitly replacing sitting time with physical activity (including standing) on metabolic parameters as outcomes were included...

  13. Amphiphilic nanoparticles suppress droplet break-up and increase serial droplet interrogation rate

    Science.gov (United States)

    Kim, Minkyu; Gai, Ya; Pan, Ming; Tang, Sindy K. Y.

    2017-11-01

    We describe the break-up behavior of a concentrated emulsion comprising drops stabilized by amphiphilic silica nanoparticles (`NPs') flowing in a tapered microchannel. Such channel geometry is commonly used in droplet serial interrogation and assay. We focus on concentrated emulsions as they often form after the droplet incubation. Unlike solid wells in their multi-well plate counterpart, drops are prone to interfacial instability. Droplet break-up ruins assay accuracy. The rate at which break-up occurs sets the limit for assay throughput. Previously, we have studied the break-up of surfactant-stabilized drops in a concentrated emulsion. The key motivation for replacing surfactants with NPs is that NPs can mitigate inter-drop transport of small molecules. Our results show replacing surfactant with NPs as droplet stabilizers has an additional advantage of reducing droplet break-up, thereby increasing the droplet interrogation rate. Such result can be attributed to the increased interfacial viscoelasticity. We examine the effect of channel confinement, viscosity ratio, and size of NPs on the break-up behavior of drops. We find the break-up is dependent on confinement and size of NPs, while insensitive to viscosity ratio within the tested range. Our results have immediate practical use in increasing the throughput limit of droplet-based applications such as serial assay and interrogation.

  14. Break-up of droplets in a concentrated emulsion flowing through a narrow constriction.

    Science.gov (United States)

    Rosenfeld, Liat; Fan, Lin; Chen, Yunhan; Swoboda, Ryan; Tang, Sindy K Y

    2014-01-21

    This paper describes the break-up of droplets in a concentrated emulsion during its flow as a 2D monolayer in a microchannel consisting of a narrow constriction. Analysis of the behavior of a large number of drops (N > 4000) shows that the number of break-ups increases with increasing flow rate, entrance angle to the constriction, and size of the drops relative to the width of the constriction. As single drops do not break at the highest flow rate used in the system, break-ups arise primarily from droplet-droplet interactions. Analysis of droplet properties at a high temporal resolution of 10 microseconds makes it possible to relate droplet deformation with droplet break-up probability. Similar to previous studies on single drops, no break-up is observed below a set of critical flow rates and droplet deformations. Unlike previous studies, however, not all drops undergo break-up above the critical values. Instead, the probability of droplet break-up increases with flow rate and the deformation of the drops. The probabilistic nature of the break-up process arises from the stochastic variations in the packing configuration of the drops as they enter the constriction. Local break-up dynamics involves two primary drops. A close look at the interactions between the pair of drops reveals that the competing time scales of droplet rearrangement relative to the relaxation of the opposing drop govern whether break-up occurs or not. Practically, these results can be used to calculate the maximum throughput of the serial interrogation process often employed in droplet microfluidics. For 40 pL-drops, the highest throughput with less than 1% droplet break-up was measured to be approximately 7000 drops per second. In addition, the results presented are useful for understanding the behavior of concentrated emulsions in applications such as mobility control in enhanced oil recovery, and for extrapolating critical parameters such as injection rates to ensure the stability of the

  15. Structures revealed in the neutron-proton mass spectrum in the deuteron break-up reaction

    Science.gov (United States)

    Siemiarczuk, T.; Stepaniak, J.; Zieliński, P.

    1983-09-01

    A sample of “non-spectator” events in the dp→(pn) p break-up reaction at 3.3 GeV/ c deuteron momentum is studied using films from 1 m hydrogen bubble chamber. The effective mass distribution of two nucleons from the deuteron break-up exhibits enhancements near the sum of neutron and proton masses and at Mpn = 2020 and 2130 MeV.

  16. Neutron induced electron radiography

    International Nuclear Information System (INIS)

    Andrade, Marcos Leandro Garcia

    2008-01-01

    In the present paper a new radiography technique, the 'Neutron Induced Electron Radiography' - NIER, to inspect low thickness samples on the order of micra, has been developed. This technique makes use of low energy electrons as penetrating radiation generated from metallic gadolinium screens when irradiated by thermal neutrons. The conditions to obtain the best image for the conventional X-ray film Kodak-AA were determined by using a digital system to quantify the darkening level of the film. The irradiations have been performed at a radiography equipment installed at the beam-hole no. 8 of the 5 MW IEA-R1 nuclear research reactor of IPEN-CNEN/SP. The irradiation time to obtain the best radiography was 100 seconds and for such condition the technique was able to discern 1 μm in 24 μm of aluminum at a resolution of 32 μm. By visual comparison the images obtained by the NIER shown a higher quality when compared with the ones from other usual techniques the make use of electrons a penetrating radiation and films for image registration. Furthermore the use of the digital system has provided a smaller time for data acquisition and data analysis as well as an improvement in the image visualization. (author)

  17. Contributions of evaporation and other mechanisms to tear film thinning and break-up.

    Science.gov (United States)

    King-Smith, P Ewen; Nichols, Jason J; Nichols, Kelly K; Fink, Barbara A; Braun, Richard J

    2008-08-01

    To evaluate the contribution of three mechanisms-evaporation of the tear film, inward flow of water into the corneal epithelium or contact lens, and "tangential flow" along the surface of epithelium or contact lens-to the thinning of the tear film between blinks and to tear film break-up. In addition to a discussion of relevant studies, some previously unpublished images are presented illustrating aspects of tear film break-up. CONTRIBUTIONS OF THREE MECHANISMS TO TEAR FILM BREAK-UP: Inward flow of water into the epithelium or contact lens is probably unimportant, and a small flow in the opposite direction may actually occur. Tangential flow is probably important in certain special cases of tear film break-up-at the black line near the tear meniscus, over surface elevations, after partial blinks, and from small thick lipid spots in the tear film. In all these special cases it is argued that tangential flow is important initially, but evaporation may be needed for final thinning to break-up. It is argued that most of the observed tear film thinning between blinks is due to evaporation, rather than tangential flow, and that large "pool" break-up regions are the result of evaporation over an extended area. Evaporation in our "free-air" conditions may be four to five times faster than the average of the values reported in the literature when air currents are prevented by preocular chambers. However, recent evaporation measurements using "ventilated chambers" give higher values, which may correspond better to free-air conditions. Thus evaporation may be fast enough to explain many cases of tear film break-up, and to give rise to considerable increases in the local osmolarity of the tear film between blinks.

  18. Breaking Up Sitting with Light-Intensity Physical Activity: Implications for Shift-Workers

    Directory of Open Access Journals (Sweden)

    Grace E. Vincent

    2017-10-01

    Full Text Available Prolonged sitting, restricted sleep, and circadian disruption are all independent risk factors for non-communicable diseases. Previous research has demonstrated that breaking up sitting with light-intensity physical activity has clear benefits for the health of day workers, but these findings may not apply in the presence of sleep restriction and/or circadian disruption—both of which are commonly experienced by shift-workers. Specifically, sleep restriction, and circadian disruption result in acute physiological changes that may offset the benefits of breaking up sitting. This commentary will explore the potential benefits of breaking up sitting for health, work performance, and subsequent sleep in shift-workers. Future areas of research designed to understand the mechanisms by which prolonged sitting and shift work impact worker health and safety and to support the design of effective occupational health and safety interventions are proposed.

  19. Study of pairing and clusterisation in light nuclei through nuclear break-up

    Directory of Open Access Journals (Sweden)

    Assié Marlène

    2014-03-01

    Full Text Available Nuclear break-up is a powerful tool to investigate nuclear structure as it is sensitive to the quantum properties of the emitted particles. This reaction mechanism has been used to investigate several aspects of correlations. First, the case of 11Be was studied where the spectroscopic factors for the two configurations where extracted. Secondly, the spectroscopic factor for alpha clusterization in the ground state of 40Ca was measured. Finally the correlation between the two neutrons in the halo of 6He emitted through break-up reactions showed strong contribution for the di-neutron configuration.

  20. Computational modeling of ice cracking and break-up from helicopter blades

    KAUST Repository

    Shiping, Zhang

    2012-06-25

    In order to reduce the danger of impact onto components caused by break-up, it is important to analyze the shape of shed ice accumulated during flight. In this paper, we will present a 3D finite element method (FEM) to predict the shed ice shape by using a fluid-solid interaction (FSI) approach to determine the loads, and linear fracture mechanics to track crack propagation. Typical icing scenarios for helicopters are analyzed, and the possibility of ice break-up is investigated.

  1. Effect of enterprise break-ups on performance: case of former Yugoslav Republic of Macedonia

    Czech Academy of Sciences Publication Activity Database

    Domadenik, P.; Lízal, Lubomír; Pahor, M.

    -, č. 216 (2003), s. 1-32 ISSN 1211-3298 R&D Projects: GA AV ČR KSK8002119 Keywords : enterprise break- ups * performance * Macedonia Subject RIV: AH - Economics http://www.cerge-ei.cz/pdf/wp/Wp216.pdf

  2. The effects of Vitamin A on tear break-up time of young adults ...

    African Journals Online (AJOL)

    This study was carried out to determine the effect of increased intake of vitamin A on Tear break-up time (TBUT). One hundred asymptomatic healthy young adults; 50 males and 50 females all within the ages of 18 and 30 years were used for this study. Results showed a range of 13-28 seconds and a mean TBUT of

  3. Computational and experimental study of the effect of mass transfer on liquid jet break-up

    Science.gov (United States)

    Schetz, J. A.; Situ, M.

    1983-06-01

    A computational method has been developed to predict the effect of mass transfer on liquid jet break-up in coaxial, low velocity gas streams. Two conditions, both with and without the effect of mass transfer on the jet break-up, are calculated, and compared with experimental results and the classical linear theory. Methanol and water were used as the injectants. The numerical solution can predict the instantaneous shape of the jet surface and the break-up time, and it is very close to the experimental results. The numerical solutions and the experimental results both indicate that the wave number of the maximum instability is about 6.9, higher than 4.51 which was predicted by Rayleigh's linear theory. The experimental results and numerical solution show that the growth of the amplitude of the trough is faster than the growth of the amplitude of the crest, especially for a rapidly vaporizing jet. The numerical solutions show that for the small rates of evaporation, the effect of the mass transfer on the interface has a stabilizing effect near the wave number for maximum instability. Inversely, it has a destabilizing effect far from the wave number for maximum instability. For rapid evaporation, the effect of the mass transfer always has a destabilizing effect and decreases the break-up time of the jet.

  4. The relation between invasive and non-invasive tear break-up time ...

    African Journals Online (AJOL)

    Tear stability normal to Nigerians with consideration of gender and age has not been reported. Tear stability in young adults was measured using invasive and non-invasive tear break-up time (TBUT and NIBUT). Forty –five subjects aged 20 to 30 years were selected from among the students of University of. Benin, Edo ...

  5. Study of the deuteron break-up with protons and neutrons

    International Nuclear Information System (INIS)

    Kumpf, H.; Moeller, K.; Moesner, J.; Schmidt, G.

    1977-06-01

    A review is given on the present situation and the results obtained in the experimental and theoretical investigation of the break-up of deuterons by protons and neutrons at bombarding energies up to 50 MeV. The nonrelativistic three-particle kinematics, experimental techniques and the basic theoretical equations for three particle scattering are described and the most important experimental results of the last years are discussed together with theoretical interpretation. It is shown that the reaction mechanism of the N-d break-up is well understood and that one can extract two-particle low energy scattering parameters (e.g., the n-n scattering length) with good accuracy. But despite of a relatively good agreement between experimental spectra and theoretical calculations (except polarisation measurements) no reliable quantitative information on the off-shell behaviour of the two-particle interaction and on three-body forces can be obtained at present. (author)

  6. Population of Metastable States in Stable Hafnium and Ytterbium Nuclei via Beam Break-up

    International Nuclear Information System (INIS)

    Malwela, T.; Ntshangase, S.S.; Shirinda, O.; Bark, R.A.; Gueorguieva, E.; Lawrie, J.J.; Mullins, S.M.; Murray, S.H.T.; Sharpey-Schafer, J.F.; Gal, J.; Kalinka, G.; Krasznahorkay, A.; Molnar, J.; Nyako, B.M.; Timar, J.; Zolnai, L.; Hlatshwayo, T.; Juhasz, K.; Komati, F.S.; Scheurer, J.N.

    2005-01-01

    The ''Chessboard'' section of the DIAMANT charged-particle array has been coupled with the AFRODITE γ-ray spectrometer at the iThemba Laboratory for Accelerator Based Sciences. Charged-particle-γ-ray coincidence data were recorded during the bombardment of a 176Yb target with a 13C beam at an energy of 90 MeV. The purpose of the investigation was to study the population of metastable states in hafium nuclei via incomplete fusion reactions in which the beam breaks up due to its α-cluster character. Of note was the observation of the band based on the Kπ = 16+, T1/2 = 31 year isomer in 178Hf to its 19+ member. Also, decays from the high-K isomeric states in 174Yb and 176Yb. which were populated via 3αxn channels, indicative of complete break-up of the 13C beam

  7. Sub-picosecond pulse break-up in an InGaAsP optical amplifier

    DEFF Research Database (Denmark)

    Romstad, Francis Pascal

    For high-speed optical communication systems with data speed higher than 200 Gb/s sub-picosecond pulse dynamics, coherent effects become important. We have, experimentally and theoretically, investigated the pulse distortion of a 150 fs pulse due to amplification in a 250 μm long InGaAsP ridge...... broadening and eventual break-up for input pulse energies on the order of picoJoules. This break-up is present in the gain region (6-14 dB), while for absorption (-6 dB9 and transparency, pulse narrowing by a factor of two is evidenced. We observe that not only the amplitude is modulated, but also the linear...

  8. Sub-picosecond pulse break-up in an InGaAsP optical amplifier

    DEFF Research Database (Denmark)

    Romstad, Francis Pascal

    1999-01-01

    For high speed optical communication system with data speed higher than 200 Gb/s sub-picosecond pulse dynamics, coherent effects become important.We have, experimentally and theoretically, investigated the pulse distortion of an 150 fs pulse due to amplification in a 250 ìm long InGaAsP ridge...... broadening and eventual break-up for input pulse energies on the order of picoJoules. This break-up is present in the gain region (6-14 dB), while for absorption (-6 dB) and transparency, pulse narrowing by a factor of two is evidenced. We observe that not only the amplitude is modulated, but also the linear...

  9. Contemporaneous assembly of Western Gondwana and final Rodinia break-up: Implications for the supercontinent cycle

    OpenAIRE

    Oriolo, Sebastián; Oyhantçabal, Pedro; Wemmer, Klaus; Siegesmund, Siegfried

    2017-01-01

    Geological, geochronological and isotopic data are integrated in order to present a revised model for the Neoproterozoic evolution of Western Gondwana. Although the classical geodynamic scenario assumed for the period 800–700 Ma is related to Rodinia break-up and the consequent opening of major oceanic basins, a significantly different tectonic evolution can be inferred for most Western Gondwana cratons. These cratons occupied a marginal position in the southern hemisphere with respect to Rod...

  10. A Southern Hemisphere origin for campanulid angiosperms, with traces of the break-up of Gondwana

    OpenAIRE

    Beaulieu, Jeremy M; Tank, David C; Donoghue, Michael J

    2013-01-01

    Background New powerful biogeographic methods have focused attention on long-standing hypotheses regarding the influence of the break-up of Gondwana on the biogeography of Southern Hemisphere plant groups. Studies to date have often concluded that these groups are too young to have been influenced by these ancient continental movements. Here we examine a much larger and older angiosperm clade, the Campanulidae, and infer its biogeographic history by combining Bayesian divergence time informat...

  11. Interaction of vector solitons and beam break up at thin film gallium-silica waveguide structure

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Arvind, E-mail: arvindsharma230771@gmail.com; Nagar, A. K., E-mail: ajaya.nagar@gmail.com [Department of Physics, Govt. Dungar College Bikaner, Rajasthan (India)

    2016-05-06

    We investigate the interaction of optical vector soliton with a symmetric thin-film gallium-silica waveguide structure using the equivalent particle theory. The relevant nonlinear Schrodinger equation has been solved by the method of phase plane analysis. The analysis shows beam break up into transmitted, reflected and nonlinear surface waves at the interface. The stability properties of the solitons so formed have been discussed.

  12. Quantifying the effects of the break up of Pangaea on global terrestrial diversification with neutral theory

    OpenAIRE

    Jordan, S; Barraclough, T; Rosindell, JL

    2016-01-01

    The historic richness of most taxonomic groups increases substantially over geological time. Explanations for this fall broadly into two categories: bias in the fossil record and elevated net rates of diversification in recent periods. For example, the break up of Pangaea and isolation between continents might have increased net diversification rates. In this study, we investigate the effect on terrestrial diversification rates of the increased isolation between land masses brought about by c...

  13. A Southern Hemisphere origin for campanulid angiosperms, with traces of the break-up of Gondwana.

    Science.gov (United States)

    Beaulieu, Jeremy M; Tank, David C; Donoghue, Michael J

    2013-04-08

    New powerful biogeographic methods have focused attention on long-standing hypotheses regarding the influence of the break-up of Gondwana on the biogeography of Southern Hemisphere plant groups. Studies to date have often concluded that these groups are too young to have been influenced by these ancient continental movements. Here we examine a much larger and older angiosperm clade, the Campanulidae, and infer its biogeographic history by combining Bayesian divergence time information with a likelihood-based biogeographic model focused on the Gondwanan landmasses. Our analyses imply that campanulids likely originated in the middle Albian (~105 Ma), and that a substantial portion of the early evolutionary history of campanulids took place in the Southern Hemisphere, despite their greater species richness in the Northern Hemisphere today. We also discovered several disjunctions that show biogeographic and temporal correspondence with the break-up of Gondwana. While it is possible to discern traces of the break-up of Gondwana in clades that are old enough, it will generally be difficult to be confident in continental movement as the prime cause of geographic disjunctions. This follows from the need for the geographic disjunction, the inferred biogeographic scenario, and the dating of the lineage splitting events to be consistent with the causal hypothesis.

  14. COMPLEX SIMULATION MODEL OF TRAIN BREAKING-UP PROCESS AT THE HUMPS

    Directory of Open Access Journals (Sweden)

    E. B. Demchenko

    2015-11-01

    Full Text Available Purpose. One of the priorities of station sorting complex functioning improvement is the breaking-up process energy consumptions reduction, namely: fuel consumption for train pushing and electric energy consumption for cut braking. In this regard, an effective solution of the problem of energy consumption reduction at breaking-up subsystem requires a comprehensive handling of train pushing and cut rolling down processes. At the same time, the analysis showed that the current task of pushing process improvement and cut rolling down effectiveness increase are solved separately. To solve this problem it is necessary to develop the complex simulation model of train breaking up process at humps. Methodology. Pushing process simulation was done based on adapted under the shunting conditions traction calculations. In addition, the features of shunting locomotives work at the humps were taken into account. In order to realize the current pushing mode the special algorithm of hump locomotive controlling, which along with the safety shunting operation requirements takes into account behavioral factors associated with engineer control actions was applied. This algorithm provides train smooth acceleration and further movement with speed, which is close to the set speed. Hump locomotive fuel consumptions were determined based on the amount of mechanical work performed by locomotive traction. Findings. The simulation model of train pushing process was developed and combined with existing cut rolling down model. Cut initial velocity is determined during simulation process. The obtained initial velocity is used for further cut rolling process modeling. In addition, the modeling resulted in sufficiently accurate determination of the fuel rates consumed for train breaking-up. Originality. The simulation model of train breaking-up process at the humps, which in contrast to the existing models allows reproducing complexly all the elements of this process in detail

  15. Central Atlantic Break-up: A competition between CAMP Hotspot and thinning rate.

    Science.gov (United States)

    Sapin, F.; Maurin, T.

    2017-12-01

    The break-up of the Central Atlantic is known to have ended at about 190Myrs while the CAMP (Central Atlantic Magmatic Province) was still active. Several seismic lines, acquired recently in the deep offshore Senegal and Mauritanian domain, provide detailed images of continent-ocean transition and the oceanic crust architecture. Their interpretation is the opportunity to describe the progressive interaction between the hot spot activity, the architecture and timing of break up and the oceanic crust production. In the North, seismic data and gravity/magnetic inversions suggest an extremely thinned continental crust with possible mantle exhumation. In the South, the continental crust is thick and the transition to oceanic crust is sharp. In addition, three oceanic crust facies were described along the margin in an extremely slow spreading ridge setting ( 0.8cm/yr during the first 20Myrs): facies (1) with a poorly imaged Moho and a strongly faulted thin oceanic crust or exhumed mantle; facies (2) with an extensively faulted 6km thick oceanic crust; facies (3) with abnormally thick (9km) oceanic crust marked by SDR-type reflections. They are diachronous from North to South and the two first one disappear southwards and (facies 3) being younger toward the North. Only a single very thick oceanic crust (12-14km) remains in front of the Guinea Plateau. We concluded that, in the South, the break-up had been forced through a thick or thickened continental crust due to the remnant activity of the CAMP Hotspot. In the North, the magmatic pulse arrived far after the break-up during the spreading and the thinning of the continental crust could lead to hyper extension. This evolution emphasizes that the architecture, and thus processes leading to the break-up can vary a lot considering the influence of thermal vertical forces (mantle dynamics/hotspot/magmatism) and mechanical horizontal forces (plate movement/faulting/spreading), both of them being necessary for a rift to succeed.

  16. Parental break-ups and stress: roles of age & family structure in 44 509 pre-adolescent children.

    Science.gov (United States)

    Dissing, Agnete S; Dich, Nadya; Andersen, Anne-Marie Nybo; Lund, Rikke; Rod, Naja H

    2017-10-01

    Parental break-up is wide spread, and the effects of parental break-up on children's well-being are known. The evidence regarding child age at break-up and subsequent family arrangements is inconclusive. Aim: to estimate the effects of parental break-up on stress in pre-adolescent children with a specific focus on age at break-up and post-breakup family arrangements. We used data from the Danish National Birth Cohort. Participants included 44 509 children followed from birth to age 11. Stress was self-reported by children at age 11, when the children also reported on parental break-up and post break-up family arrangements. Twenty-one percent of the children had experienced a parental break-up at age 11, and those who had experienced parental break-up showed a higher risk of stress (OR:1.72, 95%CI:1.55;1.91) regardless of the child's age at break-up. Children living in a new family with stepparents (OR = 1.63, 95%CI:1.38;1.92), or shared between the parents (OR = 1.48, 95%CI:1.26;1.75) reported higher stress than children of intact families. Single parent families reported markedly higher stress levels than children in intact families (OR = 2.18, 95%CI:1.90;2.50) and all other family types. Children who were satisfied with their living arrangements post-break-up reported the same stress level as children living in intact families (OR = 1.01, 95%CI:0.86;1.18). Children who experience parental break-up have higher stress levels, also many years after the break-up, and those living in a single parent household post break-up seem to be most vulnerable. Living arrangements post-breakup should be further investigated as a potential protective factor. © The Author 2017. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

  17. Study of a clusters in 40Ca and 40Ar through nuclear break-up

    International Nuclear Information System (INIS)

    Lefebvre, Laurent

    2013-01-01

    Nuclei are complex self-bound systems formed by nucleons. Conjointly to a mean-field picture in which nucleons can be regarded as independent particles, few nucleons might self-organize into compact objects, called clusters, inside the nucleus. It is theoretically predicted that it should manifest itself most strikingly for N = Z nuclei close to the emission thresholds and has been studied extensively in this region. We propose to study α-clusterization in the ground state of the N = Z 40 20 Ca 20 nucleus and the N (different of) Z 40 18 Ar 22 nucleus. We have studied the nuclear break-up of 40 Ca when the 40 Ar projectile passes by. If α clusters are preformed in 40 Ca, the probability of α-emission through nuclear break-up will be enhanced as compared to 40 Ar N (different of) Z nuclei.The nuclear break-up of 40 Ca was studied with an 40 Ar beam produced at GANIL at 35 MeV/A. The SPEG spectrometer was used to detect the heavy projectile with accurate resolution. The MUST2 Silicon detectors were placed around the target to measure the emitted α and the EXL calorimeter prototype was used to identify the γ rays from the decay of the residual 36 Ar and 36 S. A theoretical approach based on Time-Dependent Schroedinger Equation (TDSE) theory has been used to reproduce some experimental results like angular distributions. From the data analysis, we reconstructed excitation energy spectra and angular distributions which are compared to TDSE theory to extract some spectroscopic factors S α . These factors show that there is no more clusterization state in the ground state of the 40 Ca than in the ground state of 40 Ar. (author)

  18. Experimental investigation of hysteresis in the break-up of liquid curtains

    KAUST Repository

    Marston, Jeremy

    2014-09-01

    Findings from an experimental investigation of the break-up of liquid curtains are reported, with the overall aim of examining stability windows for multi-layer liquid curtains composed of Newtonian fluids, where the properties of each layer can be kept constant or varied. For a single-layer curtain it is known that the minimum flow rate required for initial stability can be violated by carefully reducing the flow rate below this point, which defines a hysteresis region. However, when two or three layers are used to form a composite curtain, the hysteresis window can be considerably reduced depending on the experimental procedure used. Extensive quantitative measurements of this hysteresis region are provided alongside an examination of the influence of physical properties such as viscosity and surface tension. The origins of curtain break-up for two different geometries are analysed; first where the curtain width remains constant, pinned by straight edge guides; and second where the curtain is tapered by angled edge guides. For both cases, the rupture speed is measured, which appears to be consistent with the Taylor-Culick velocity. Observations of the typical linearly spaced jets which form after the break-up has transpired and the periodicity of these jets are compared to the Rayleigh-Taylor wavelength and previous experimental measurements. Furthermore, the curtain stability criterion originally developed by Brown (1961), summarised in terms of a Weber number, has recently been extended to multi-layer curtains by Dyson et al. (2009); thus this report provides the first experimental measurements which puts this to the test. Ultimately, it is found that only the most viscous and polymer-based liquids violate this criterion. © 2014 Elsevier Ltd.

  19. Analysis of a gas stratification break-up by a vertical jet using the GOTHIC code

    International Nuclear Information System (INIS)

    Fernández-Cosials, Mikel Kevin; Jimenez, Gonzalo; Lopez-Alonso, Emma

    2016-01-01

    Highlights: • Study of a light gas distribution with the GOTHIC code based on the OECD/NEA IBE-3. • Sensitivity analysis on turbulence model, discretization scheme and heat transfer. • The jet erosion phenomena is captured properly with a relatively coarse mesh. • Development of a tool to evaluate the influence of each parameter on the simulation. • Several recommendation on modeling a stratification break-up are included. - Abstract: During a severe accident in light water reactor (LWR), hydrogen concentration can overpass the flammability limits locally, so the correct simulation of its behavior during a release is critical. The capability assessment of computational fluid dynamics tools to calculate the hydrogen distribution under different conditions has been the focus of intense research worldwide. In this context, the OECD/NEA conducted an international benchmark exercise (IBE-3), which was focused on the break-up of a stratified layer of a light gas by a vertical jet. The participants performed their simulations before the experiment data was released. When the data was released, it was noticed that a combination of several parameters like the mesh, turbulence model or solver controls were responsible for the broad differences between the participants’ results. To obtain information about how each parameter affects the simulation, a post-test sensitivity analysis has been done by the UPM. In this paper, the IBE-3 experiment simulation with GOTHIC 8.0 is presented along with extensive sensitivity analyses of the relevant parameters. The first objective of the work is to test the capability of GOTHIC 8.0 to simulate properly a gas stratification break-up by a vertical jet with a relatively coarse mesh. The second objective of the paper is to relate each sensitivity parameter with each other and with the experiment through the Parameter Influence Chart, a helpful tool specially designed for this purpose.

  20. Analysis of a gas stratification break-up by a vertical jet using the GOTHIC code

    Energy Technology Data Exchange (ETDEWEB)

    Fernández-Cosials, Mikel Kevin; Jimenez, Gonzalo, E-mail: gonzalo.jimenez@upm.es; Lopez-Alonso, Emma

    2016-02-15

    Highlights: • Study of a light gas distribution with the GOTHIC code based on the OECD/NEA IBE-3. • Sensitivity analysis on turbulence model, discretization scheme and heat transfer. • The jet erosion phenomena is captured properly with a relatively coarse mesh. • Development of a tool to evaluate the influence of each parameter on the simulation. • Several recommendation on modeling a stratification break-up are included. - Abstract: During a severe accident in light water reactor (LWR), hydrogen concentration can overpass the flammability limits locally, so the correct simulation of its behavior during a release is critical. The capability assessment of computational fluid dynamics tools to calculate the hydrogen distribution under different conditions has been the focus of intense research worldwide. In this context, the OECD/NEA conducted an international benchmark exercise (IBE-3), which was focused on the break-up of a stratified layer of a light gas by a vertical jet. The participants performed their simulations before the experiment data was released. When the data was released, it was noticed that a combination of several parameters like the mesh, turbulence model or solver controls were responsible for the broad differences between the participants’ results. To obtain information about how each parameter affects the simulation, a post-test sensitivity analysis has been done by the UPM. In this paper, the IBE-3 experiment simulation with GOTHIC 8.0 is presented along with extensive sensitivity analyses of the relevant parameters. The first objective of the work is to test the capability of GOTHIC 8.0 to simulate properly a gas stratification break-up by a vertical jet with a relatively coarse mesh. The second objective of the paper is to relate each sensitivity parameter with each other and with the experiment through the Parameter Influence Chart, a helpful tool specially designed for this purpose.

  1. When They Break Up and Get Back Together: Length of Adolescent Romantic Relationships and Partner Concurrency

    Science.gov (United States)

    Matson, Pamela Ann; Chung, Shang-en; Ellen, Jonathan Mark

    2012-01-01

    BACKGROUND Sex partner concurrency is an important risk factor for STI transmission. Understanding how adolescents conceptualize the length of their relationships when they break up and get back together is essential to the assessment of concurrency. METHODS A prospective cohort of 392 late adolescents and emerging adults, aged 14 – 19 years at baseline, were recruited from two clinics in Baltimore, MD and interviewed semi-annually for 3 years. At each interview, participants were asked to report on all of their sexual partners in the previous six months, the length of relationship and whether they thought their partner had other sex partners. For relationships that had broken up and gotten back together, reports of length of the relationship were compared before and after the break up. Random effects logistic regression was used to examine the association between length of relationship and both break up and partner concurrency. RESULTS For relationships that ended and subsequently got back together, participants considered the length of relationship to include the period when they were broken up. Longer relationships were at increased odds of both having broken up and gotten back together [OR = 1.04, 95% CI: 1.02, 1.05] and of partner concurrency [OR = 1.03, 95% CI: 1.02, 1.04]. The magnitude of the odds of concurrency was greater for relationships that had broken up and gotten back together [OR = 1.07, 95% CI: 1.02, 1.11]. CONCLUSIONS Findings from this study emphasize the need for an improved understanding of the association between the temporal dynamics of late adolescent and emerging adult romantic relationships and concurrency. PMID:22421694

  2. Contemporaneous assembly of Western Gondwana and final Rodinia break-up: Implications for the supercontinent cycle

    Directory of Open Access Journals (Sweden)

    Sebastián Oriolo

    2017-11-01

    Full Text Available Geological, geochronological and isotopic data are integrated in order to present a revised model for the Neoproterozoic evolution of Western Gondwana. Although the classical geodynamic scenario assumed for the period 800–700 Ma is related to Rodinia break-up and the consequent opening of major oceanic basins, a significantly different tectonic evolution can be inferred for most Western Gondwana cratons. These cratons occupied a marginal position in the southern hemisphere with respect to Rodinia and recorded subduction with back-arc extension, island arc development and limited formation of oceanic crust in internal oceans. This period was thus characterized by increased crustal growth in Western Gondwana, resulting from addition of juvenile continental crust along convergent margins. In contrast, crustal reworking and metacratonization were dominant during the subsequent assembly of Gondwana. The Río de la Plata, Congo-São Francisco, West African and Amazonian cratons collided at ca. 630–600 Ma along the West Gondwana Orogen. These events overlap in time with the onset of the opening of the Iapetus Ocean at ca. 610–600 Ma, which gave rise to the separation of Baltica, Laurentia and Amazonia and resulted from the final Rodinia break-up. The East African/Antarctic Orogen recorded the subsequent amalgamation of Western and Eastern Gondwana after ca. 580 Ma, contemporaneously with the beginning of subduction in the Terra Australis Orogen along the southern Gondwana margin. However, the Kalahari Craton was lately incorporated during the Late Ediacaran–Early Cambrian. The proposed Gondwana evolution rules out the existence of Pannotia, as the final Gondwana amalgamation postdates latest connections between Laurentia and Amazonia. Additionally, a combination of introversion and extroversion is proposed for the assembly of Gondwana. The contemporaneous record of final Rodinia break-up and Gondwana assembly has major implications for the

  3. Break up of the azimuthal symmetry of higher order fiber modes

    DEFF Research Database (Denmark)

    Israelsen, Stine Møller; Rishøj, Lars Søgaard; Rottwitt, Karsten

    2014-01-01

    We investigate Bessel-like modes guided in a double cladding fiber where the outer cladding is an aircladding. For very high order LP0 X-modes, the azimuthal symmetry is broken and the mode is no longer linearly polarized. This is observed experimentally and confirmed numerically. The effect is i...... mode. The free space properties of modes suffering from break up of azimuthal symmetry are also investigated experimentally by measuring the free space propagation of a LP016-mode excited in the double cladding fiber. © 2014 Optical Society of America....

  4. Pangea break-up: from passive to active margin in the Colombian Caribbean Realm

    Science.gov (United States)

    Gómez, Cristhian; Kammer, Andreas

    2017-04-01

    The break-up of Western Pangea has lead to a back-arc type tectonic setting along the periphery of Gondwana, with the generation of syn-rift basins filled with sedimentary and volcanic sequences during the Middle to Late Triassic. The Indios and Corual formations in the Santa Marta massif of Northern Andes were deposited in this setting. In this contribution we elaborate a stratigraphic model for both the Indios and Corual formations, based on the description and classification of sedimentary facies and their architecture and a provenance analysis. Furthermore, geotectonic environments for volcanic and volcanoclastic rock of both units are postulated. The Indios Formation is a shallow-marine syn-rift basin fill and contains gravity flows deposits. This unit is divided into three segments; the lower and upper segments are related to fan-deltas, while the middle segment is associated to offshore deposits with lobe incursions of submarine fans. Volcanoclastic and volcanic rocks of the Indios and Corual formations are bimodal in composition and are associated to alkaline basalts. Volcanogenic deposits comprise debris, pyroclastic and lava flows of both effusive and explosive eruptions. These units record multiple phases of rifting and reveal together a first stage in the break-up of Pangea during Middle and Late Triassic in North Colombia.

  5. Rifting and magmatism associated with the South America and Africa break-up

    International Nuclear Information System (INIS)

    Thomaz Filho, Antonio; Cesero, Pedro de

    2000-01-01

    Based on about 380 K/Ar dating of basic and alkaline magmatic rocks from Brazilian sedimentary basins and the argentinean Atlantic margin it is possible to interpret the evolution of the rifting that caused the South America and Africa break-up. This process started in the Triassic and took place northwestward of the Foz do Amazonas basin, on the equatorial Brazilian continental margin, and reached the San Julian and North Malvinas basins, in the southern portion of South America. From this latter up to the Espirito Santo Basin, rifting took place between the Jurassic and Neocomian whereas transcurrence caused by clockwise rotation of South America on the equatorial margin generated the Potiguar Basin. The available information suggests that the final break-up of Africa and South America occurred along the eastern Brazilian margin, between the Cumuruxatiba/Mucuri and Pernambuco basins, during the Cenomanian/Turonian. The resistance offered by the Sao Luis/West African and Sao Francisco/Congo cratons promoted the huge magnetic manifestations which occur in the Brazilian paleozoic intracratonic basins (Acre, Solimoes, Amazonas, Paranaiba and Parana basins) as well as in the interior Tacutu Rift. Hot spots turned out during the drift phase, as registered by the Mecejana (CE)/Rocas Atoll/Fernando de Noronha Archipelago Alignment and Pocos de Caldas/Cabo Frio Alkaline Rocks Alignment that persists up to Vitoria/Trindade Chain. (author)

  6. Infant mortality in Kyrgyzstan before and after the break-up of the Soviet Union.

    Science.gov (United States)

    Guillot, Michel; Lim, So-Jung; Torgasheva, Liudmila; Denisenko, Mikhail

    2013-01-01

    There is a great deal of uncertainty over the levels of, and trends in, infant mortality in the former Soviet republics of Central Asia. As a result, the impact of the break-up of the Soviet Union on infant mortality in the region is not known, and proper monitoring of mortality levels is impaired. In this paper, a variety of data sources and methods are used to assess levels of infant mortality and their trend over time in one Central Asian republic, Kyrgyzstan, between 1980 and 2010. An abrupt halt to an already established decline in infant mortality was observed to occur during the decade following the break-up of the Soviet Union, contradicting the official statistics based on vital registration. Infants of Central Asian ethnicity and those born in rural areas were also considerably more at risk of mortality than suggested by the official sources. We discuss the implications of these findings, both for health policy in this seldom studied part of the former Soviet Union and for our understanding of the health crisis which it currently faces.

  7. Influence of thermal fluctuations on ligament break-up: a fluctuating lattice Boltzmann study

    Science.gov (United States)

    Xue, Xiao; Biferale, Luca; Sbragaglia, Mauro; Toschi, Federico

    2017-11-01

    Thermal fluctuations are essential ingredients in a nanoscale system, driving Brownian motion of particles and capillary waves at non-ideal interfaces. Here we study the influence of thermal fluctuations on the breakup of liquid ligaments at the nanoscale. We offer quantitative characterization of the effects of thermal fluctuations on the Plateau-Rayleigh mechanism that drives the breakup process of ligaments. Due to thermal fluctuations, the droplet sizes after break-up need to be analyzed in terms of their distribution over an ensemble made of repeated experiments. To this aim, we make use of numerical simulations based on the fluctuating lattice Boltzmann method (FLBM) for multicomponent mixtures. The method allows an accurate and efficient simulation of the fluctuating hydrodynamics equations of a binary mixture, where both stochastic viscous stresses and diffusion fluxes are introduced. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No 642069.

  8. Capillary break-up, gelation and extensional rheology of hydrophobically modified cellulose ethers

    Science.gov (United States)

    Sharma, Vivek; Haward, Simon; Pessinet, Olivia; Soderlund, Asa; Threlfall-Holmes, Phil; McKinley, Gareth

    2012-02-01

    Cellulose derivatives containing associating hydrophobic groups along their hydrophilic polysaccharide backbone are used extensively in the formulations for inks, water-borne paints, food, nasal sprays, cosmetics, insecticides, fertilizers and bio-assays to control the rheology and processing behavior of multi-component dispersions. These complex dispersions are processed and used over a broad range of shear and extensional rates. The presence of hydrophobic stickers influences the linear and nonlinear rheology of cellulose ether solutions. In this talk, we systematically contrast the difference in the shear and extensional rheology of a cellulose ether: ethy-hydroxyethyl-cellulose (EHEC) and its hydrophobically-modified analog (HMEHEC) using microfluidic shear rheometry at deformation rates up to 10^6 inverse seconds, cross-slot flow extensional rheometry and capillary break-up during jetting as a rheometric technique. Additionally, we provide a constitutive model based on fractional calculus to describe the physical gelation in HMEHEC solutions.

  9. Comparison of mechanism of break up and cycle length in defibrillation success

    Science.gov (United States)

    Melkus, Natalya; Puwal, Steffan

    2012-10-01

    Heart fibrillation is an often fatal condition which can be modeled by chaotic electrical activity; spiral waves of electrical activity rotate, break-up, and meander on tissue. As they do, they produce a chaotic distribution of electrical activity, negatively affecting physical contraction (blood pumping). Fenton, et al. studied several mechanisms of this wave breakup, including ``far from tip'' and ``Doppler shift.'' We used Fenton et al.'s mathematical model and the different modes of breakup proposed by Fenton to simulate fibrillation and to determine if the cycle length of the activity or the type of mechanism was more significant in defibrillation. Our data supports the conclusion that the cycle length is the more important factor in defibrillation.

  10. Interplay of break-up and transfer processes in reactions involving weakly-bound systems

    Science.gov (United States)

    Vitturi, Andrea; Moschini, Laura

    2018-02-01

    In this note we illustrate some applications of a simple model which has been devised to clarify the reaction mechanism and the interplay of different reaction channels (elastic, inelastic, transfer, break-up) in heavy-ion collisions. The model involves two potential wells moving in one dimension and few active particles; in spite of its simplicity, it is supposed to maintain the main features, the properties and the physics of the full three-dimensional case. Special attention is given to the role of continuum states in reactions involving weakly-bound systems, and different approximation schemes (as first-order or coupled-channels) as well as different continuum discretization procedures are tested. In the case of two active particles the reaction mechanism associated with two-particle transfer and the effect of pairing intearction are investigated. Work done in collaboration with Antonio Moro and Kouichi Hagino

  11. Projective multifragments break-up and the electromagnetic field effect of target nucleus

    International Nuclear Information System (INIS)

    Nabil Yasin, M.

    1994-12-01

    This work presents a special type of interactions produced in emulsion targets exposed to different incident beams of light ions at a few GeV per nucleon. The events characterised by multifragment break-up of the projectile nucleus which are produced via peripheral collisions or due to the effect of the Coulomb field of the target nucleus have been selected. The size of impact parameter must be considered for determining the type of the interaction. The results are compared with other collected data at energies (up to 200 GeV/nucleon). The dependence of electromagnetic dissociation cross section on the incident projectile energy is investigated. Also, a comparison of the experimental data with the assumed virtual photon spectrum using Weizsaecker-Williams (WW) method is made. (author). 34 refs, 3 figs, 4 tabs

  12. Drop break-up and pressure measurements in a microfluidic device

    Science.gov (United States)

    Protiere, Suzie; Stone, Howard A.; Weitz, David A.

    2008-11-01

    We study experimentally the flow of an emulsion passing through one or a few constrictions placed in a microfluidic channel. Using a high-speed differential manometer placed in the same device (M. Abkarian et al. PNAS 200:16407104 (2006)) we have measured the dynamic pressure as a drop breaks up when it meets one or several constrictions. We can then study how a global measurement of the pressure drop indicates the sequence of phenomena occurring in the channel (breakup, trapped and squeezed drops etc.). In a separate set of experiments with a microfluidic model of a two-dimensional porous medium through which drops flow we can observe the various phenomena and thus correlate the pressure fluctuations to single events at the pore scale.

  13. Gas stratification break-up by a vertical jet: Simulations using the GOTHIC code

    International Nuclear Information System (INIS)

    Andreani, Michele; Kapulla, Ralf; Zboray, Robert

    2012-01-01

    Highlights: ► Simulations of experiments addressing helium stratification break-up with GOTHIC are presented. ► In the tests, the initial helium-rich layer in a large vessel is eroded by a vertical jet. ► A 3-D coarse mesh and various finer 2-D meshes have been used for the simulations. ► In general, the 3-D calculations predict too slow mixing in the vessel. ► A reasonable agreement between calculated and measured gas concentrations requires a fine mesh. - Abstract: The capability assessment of three-dimensional computational tools to predict the erosion and the break-up of stratified conditions that can build-up in a containment through the release of hydrogen during an early phase of a hypothetical severe accident is the focus of intense research worldwide. In conjunction with the OECD SETH-2 project, the GOTHIC code is assessed against experiments in which mass and/or heat sources or sinks cause mixing. This paper reports on simulation results of selected experiments where the initial helium stratification in a vessel is eroded by a vertical jet originating from an injection below the initial density interface. A 3-D coarse mesh, as well as various finer 2-D meshes, is used to simulate the evolution of the helium distribution generated by jets having different initial momentum. In general, the 3-D calculations predict too slow mixing in the vessel and a reasonable agreement between calculated and measured gas concentrations can only be achieved with a sufficiently fine mesh. These results can be explained by comparing the calculated velocity field with that measured using the PIV technique, which also provides valuable insight into the mechanisms of the interaction between the jet and the density interface.

  14. MULTIPHASE DROPLET/SLUG BREAK-UP MECHANISM IN MICROFLUIDIC T-JUNCTIONS AT VARIOUS WEBER NUMBERS

    Directory of Open Access Journals (Sweden)

    Wan Leng (Dawn Leow

    2011-10-01

    Full Text Available Normal 0 false false false EN-MY X-NONE X-NONE The formation of immiscible liquid droplets, or slugs, in microchannels features the advantages of volume control and mixing enhancement over single-phase microflows. Although the applications of droplet-based microfluidics have been widely demonstrated, the fundamental physics governing droplet break-up remains an area of active research. This study defines an effective Weber (Weeff number that characterizes the interplay of interfacial tension, shear stress and channel pressure drop in driving slug formation in T-junction microchannel for a relative range of low, intermediate and high flow rates. The immiscible fluid system in this study consists of Tetradecane slug formation in Acetonitrile. The progressive deformation of slug interfaces during break-up events is observed. Experimental results indicate that, at a relatively low Weeff, clean slug break-up occurs at the intersection of the side and main channels. At intermediate Weeff, the connecting neck of the dispersed phase is stretched to a short and thin trail of laminar flow prior to breaking up a short distance downstream of the T-junction. At a relatively high Weeff, the connecting neck develops into a longer and thicker trail of laminar flow that breaks up further downstream of the main channel.

  15. Severe symptoms of short tear break-up time dry eye are associated with accommodative microfluctuations

    Directory of Open Access Journals (Sweden)

    Kaido M

    2017-05-01

    Full Text Available Minako Kaido,1,2 Motoko Kawashima,1 Reiko Ishida,1,3 Kazuo Tsubota1 1Department of Ophthalmology, Keio University School of Medicine, Tokyo, 2Wada Eye Clinic, Chiba, 3Ishida Eye Clinic, Shizuoka, Japan Aim: Validating the hypothesis that accommodative microfluctuations (AMFs may be associated with severe symptoms in short tear break-up time (BUT dry eye (DE. Methods: This study included 12 subjects with short BUT DE (age: 49.6±18.3 years. Diagnoses were performed based on the presence of DE symptoms, BUT ≤5 s, Schirmer score >5 mm, and negative keratoconjunctival epithelial damage. Tear evaluation, AMF, and functional visual acuity (VA examinations were conducted before and after DE treatment. The AMF parameters evaluated were: total high-frequency component (HFC, HFC with low accommodation for the task of staring into the distance (HFC1, HFC with high accommodation for deskwork (HFC2. A subjective questionnaire of DE symptoms was also performed. Results: Mean BUT increased from 1.9±2.0 to 6.4±2.5 s after treatment (P<0.05. The mean logarithm of the minimum angle of resolution functional VA significantly improved (from 0.19±0.19 to 0.12±0.17; P<0.05. Mean power spectrum values for total HFC and HFC1 decreased (from 61.3±5.7 to 53.8±6.6 dB and from 62.9±10.5 to 52.4±6.2 dB, respectively; P<0.05, while the mean HFC2 power spectrum values did not differ before and after treatment (P>0.05. Subjective DE symptoms were reduced in nine patients. Conclusion: Along with the improvement of BUT after treatment, DE symptoms diminished and HFC1 and functional VA improved, suggesting that tear film instability is associated with deterioration of functional VA, AMF, and DE symptoms. Keywords: accommodative microfluctuation, ciliary muscle spasm, dry eye, ocular fatigue, tear break-up time, functional visual acuity 

  16. Quantifying the effects of the break up of Pangaea on global terrestrial diversification with neutral theory.

    Science.gov (United States)

    Jordan, Sean M R; Barraclough, Timothy G; Rosindell, James

    2016-04-05

    The historic richness of most taxonomic groups increases substantially over geological time. Explanations for this fall broadly into two categories: bias in the fossil record and elevated net rates of diversification in recent periods. For example, the break up of Pangaea and isolation between continents might have increased net diversification rates. In this study, we investigate the effect on terrestrial diversification rates of the increased isolation between land masses brought about by continental drift. We use ecological neutral theory as a means to study geologically complex scenarios tractably. Our models show the effects of simulated geological events that affect all species equally, without the added complexity of further ecological processes. We find that continental drift leads to an increase in diversity only where isolation between continents leads to additional speciation through vicariance, and where higher taxa with very low global diversity are considered. We conclude that continental drift by itself is not sufficient to account for the increase in terrestrial species richness observed in the fossil record. © 2016 The Authors.

  17. Study of subnuclear degrees of freedom in electromagnetic break-up of the deuteron

    International Nuclear Information System (INIS)

    Arenhoevel, H.

    1991-01-01

    The role of subnuclear degrees of freedom in terms of meson and isobar degrees of freedom is discussed for the simplest process in nuclear physics, i.e., the electromagnetic break-up of the deuteron. The various theoretical schemes for incorporating such degrees of freedom either explicitly or as effective operators are briefly reviewed. The principle of minimal substitution as a means to construct effective two-body exchange current operators is illustrated and explicit expressions for pion exchange are given. The cross sections for photo- and electrodisintegration of the deuteron are expressed in terms of the t-matrix elements. The different theoretical methods for the calculation of the t-matrix are described and the essential ingredients for the non-relativistic evaluation including the most important relativistic corrections of lowest order are outlined. For specific experiments in photo- and electrodisintegration theoretical results are compared to experimental data and the present status of our understanding of these processes in assessed. (author). Refs, figs

  18. Sensitivity of N/Z ratio in projectile break-up of isobaric systems

    Directory of Open Access Journals (Sweden)

    De Filippo E.

    2016-01-01

    Full Text Available The binary break-up of projectile-like fragments in non central heavy-ion collisions follows different decay patterns, from equilibrated emission towards dynamical (prompt fission. Recently, comparing two systems with different N/Z in the entrance channel, it has been shown that the dynamical emission cross-section is enhanced for the most neutron rich system while the statistical emission cross-section is independent from the isotopic composition. In order to understand this dependence and disentangle it from the initial size of the nuclei, we have studied the two isobaric systems 124Xe+64 Zn and 124Xe+64 Ni at 35 A MeV (InKiIsSy experiment, in comparison with the previous studied reactions (124Sn +64 Ni and 112Sn +58 Ni at the same bombarding energy. We present the first results evidencing a striking similar effect in the dynamical decay as a function of the N/Z of the target for equal size systems.

  19. Breaking Up is Hard to Do: The Ups and Downs of Divorcing Brands

    Directory of Open Access Journals (Sweden)

    Fournier Susan

    2014-05-01

    Full Text Available Relationships with brands are like relationships between people. Even when they were very close, they can fail for diverse reasons. The disadoption of favorite brands doesn't happen overnight. It tends to be an extended, often painful process and not a clear-cut, one-off event. Breakups are not isolated to the person and the brand. Friends and family often get involved and offer their opinions and advice. Other brand relationships are also affected by the disconnection, and this can speed up or delay the process of breaking up. The brand relationship changes its form and can go from being a best friend to a platonic love, a distant friend, a stalker or even an enemy. A breakup is never the end of the relationship. Rather, it redefines the relationship and is part of a never-ending cycle of change. If the former relationship is perceived positively, it is easier to eventually activate and intensify it. If negative aspects prevail, negative word of mouth is a danger and companies must be able to counter it. Some relationships reach a point of no return. But there are also customers who might regret having abandoned a brand. With some sensitivity, it might be possible to win them back.

  20. Controlled formation of cyclopentane hydrate suspensions via capillary-driven jet break-up

    Science.gov (United States)

    Geri, Michela; McKinley, Gareth

    2017-11-01

    Clathrate hydrates are crystalline compounds that form when a lattice of hydrogen-bonded water molecules is filled by guest molecules sequestered from an adjacent gas or liquid phase. Being able to rapidly produce and transport synthetic hydrates is of great interest given their significant potential as a clean energy source and safe option for hydrogen storage. We propose a new method to rapidly produce cyclopentane hydrate suspensions at ambient pressure with tunable particle size distribution by taking advantage of the Rayleigh-Plateau instability to form a mono-disperse stream of droplets during the controlled break-up of a water jet. The droplets are immediately frozen into ice particles through immersion in a subcooled reservoir and converted into hydrates with a dramatic reduction in the nucleation induction time. By measuring the evolution of the rheological properties with time, we monitor the process of hydrates formation via surface crystallization and agglomeration with different droplet size distributions. This new method enables us to gain new insights into hydrate formation and transport which was previously hindered by uncontrolled droplet formation and hydrate nucleation processes. MITei Chevron Fellowship.

  1. When they break up and get back together: length of adolescent romantic relationships and partner concurrency.

    Science.gov (United States)

    Matson, Pamela Ann; Chung, Shang-en; Ellen, Jonathan Mark

    2012-04-01

    Sex partner concurrency is an important risk factor for sexually transmitted infection transmission. Understanding how adolescents conceptualize the length of their relationships when they break up and get back together is essential to the assessment of concurrency. A prospective cohort of 392 late adolescents and emerging adults, aged 14 to 19 years at baseline, were recruited from 2 clinics in Baltimore, MD and interviewed semiannually for 3 years. At each interview, participants were asked to report on all of their sexual partners in the previous 6 months, the length of relationship, and whether they thought their partner had other sex partners. For relationships that had broken up and gotten back together, reports of length of the relationship were compared before and after the breakup. Random effects logistic regression was used to examine the association between length of relationship and both breakup and partner concurrency. For relationships that ended and subsequently got back together, participants considered the length of relationship to include the period when they were broken up. Longer relationships were at increased odds of both having broken up and gotten back together (odds ratio [OR] = 1.04, 95% confidence interval [CI]: 1.02, 1.05) and of partner concurrency (OR = 1.03, 95% CI: 1.02, 1.04). The magnitude of the odds of concurrency was greater for relationships that had broken up and gotten back together (OR = 1.07, 95% CI: 1.02, 1.11). Findings from this study emphasize the need for an improved understanding of the association between the temporal dynamics of late adolescent and emerging adult romantic relationships and concurrency.

  2. The effect of enterprise break-ups on performance: the case of the former Yugoslav Republic of Macedonia

    Czech Academy of Sciences Publication Activity Database

    Domadenik, P.; Lízal, Lubomír; Pahor, M.

    2012-01-01

    Roč. 63, č. 5 (2012), s. 849-866 ISSN 0035-2764 Institutional support: RVO:67985998 Keywords : enterprise break-ups * Macedonia * performance Subject RIV: AH - Economics http://www.cairn.info/resume.php?ID_ARTICLE=RECO_635_0849

  3. Does the association between broken partnership and first time myocardial infarction vary with time after break-up?

    DEFF Research Database (Denmark)

    Kriegbaum, Margit; Christensen, Ulla; Andersen, Per Kragh

    2013-01-01

    Marriage is associated with lower risk of coronary heart disease, but it is unknown if the association depends on time since break-up with a partner. In this study we included both married and unmarried couples to study if the association between broken partnership (BP) and first time incident...

  4. Continental Break-up Above A Mantle Plume: Opening of The Southern Red Sea

    Science.gov (United States)

    Ebinger, C.; Eagles, G.; Elders, C.; Gloaguen, R.; McClay, K.; Tiberi, C.; Wolfenden, E.

    Initial rifting in the Red Sea occurred concurrent with, or soon after flood basaltic mag- matism at~31 Ma in the Ethiopia-Yemen plume province. Yet, the development of the ca. 400 km-wide extensional province of the southern Red Sea between 31 Ma and the onset of seafloor spreading at ~4 Ma has been poorly understood, in large part owing to inaccessibility in the Afar depression. The Afar depression is a diffuse extensional province marking a triple point zone between plate boundaries in the Red Sea (Arabia Nubia), the Gulf of Aden (Arabia Somalia); and the Main Ethiopian Rift (Somalia Nu- bia). Complicating this setting, the Danakil horst is a microplate lying between oceanic provinces in the southernmost Red Sea and incipient seafloor spreading in the northern Afar depression. We have integrated exploration seismic, gravity, well, and magnetic data from offshore regions with remote sensing, geological and geophysical data from Ethiopia, Eritrea, and Yemen to evaluate models for continental break-up above mantle plumes. Plate kinematic reconstructions using a pole of rotation within the error ellipse of the Chu and Gordon (1999) pole predict real features in remote sensing and gravity data; these reconstructions provide a general framework for our interpretations. Field and geochronology studies along the western margin of Afar show a southward prop- agation of rifting since about 25 Ma when extension commenced offshore Red Sea and in Yemen. We also see an eastward migration of strain from the western border fault to narrow zones of primarily basaltic magmatism since mid-Miocene time. These magmatic sequences, where not onlapped by Pliocene-Recent sedimentary strata, dip steeply seaward and define a regional eastward flexure into transitional oceanic crust, as suggested by gravity models constrained by existing seismic data. Our synthesis suggests that the southern Afar depression, assumed to be most proximal to the plume, was the site of incipient seafloor

  5. Modeling Gas Slug Break-up in the Lava Lake at Mt. Erebus, Antarctica

    Science.gov (United States)

    Velazquez, L. C.; Qin, Z.; Suckale, J.; Soldati, A.; Rust, A.; Cashman, K. V.

    2017-12-01

    obtained at the volcano scale will help to assess how slug break-up alters the episodicity of degassing at the lava lake surface. A thorough understanding of this model will help constrain the main processes controlling the episodic eruptions at Mt. Erebus and other, similar volcanoes.

  6. Formation of droplets and bubbles in a microfluidic T-junction-scaling and mechanism of break-up.

    Science.gov (United States)

    Garstecki, Piotr; Fuerstman, Michael J; Stone, Howard A; Whitesides, George M

    2006-03-01

    This article describes the process of formation of droplets and bubbles in microfluidic T-junction geometries. At low capillary numbers break-up is not dominated by shear stresses: experimental results support the assertion that the dominant contribution to the dynamics of break-up arises from the pressure drop across the emerging droplet or bubble. This pressure drop results from the high resistance to flow of the continuous (carrier) fluid in the thin films that separate the droplet from the walls of the microchannel when the droplet fills almost the entire cross-section of the channel. A simple scaling relation, based on this assertion, predicts the size of droplets and bubbles produced in the T-junctions over a range of rates of flow of the two immiscible phases, the viscosity of the continuous phase, the interfacial tension, and the geometrical dimensions of the device.

  7. Gendered Struggles over Residency Rights when Turkish Immigrant Marriages Break up

    Directory of Open Access Journals (Sweden)

    Anika Liversage

    2013-12-01

    Full Text Available Transnational marriages – where immigrant offspring marry spouses from their parents’ country of origin – have been common across Europe. If such marriages end in divorce before a given probationary period is over, the marriage migrant spouses may have to leave Europe again, a fact which affects the power balance in such marriages in their first years. Combining quantitative and qualitative data on divorces in Turkish transnational marriages in Denmark, this article sheds light on the interaction between gender and power in such cases of marital break-up. The statistics show that of the app. 9300 Turkish couples who married transnationally in the 1980s and 1990, around 2000 marriages ended in divorce, and app. 450-500 divorced individuals subsequently left Denmark.Interviews with divorced Turkish men and women document that gender strongly affects the power of the sponsoring spouse: While sponsoring men may act with great audacity in expelling quite powerless marriage migrant wives, sponsoring women can also seek to expel unwanted husbands. However, women may do so with greater caution and may more often have to rely on support from Danish state institutions. Furthermore, family relations – especially with the parental generation – may partially counteract the very weak positions of the marriage migrant wives. Los matrimonios transnacionales -donde descendientes de inmigrantes se casan con cónyuges del país de origen de sus padres- han sido comunes en toda Europa. Si tales matrimonios terminan en divorcio antes de que concluya el período de prueba, los cónyuges emigrantes esposados pueden tener que dejar Europa una vez más, un hecho que afecta al equilibrio de poder de esos matrimonios en sus primeros años. Combinando datos cuantitativos y cualitativos sobre divorcios de matrimonios transnacionales turcos en Dinamarca, este artículo arroja luz sobre la interacción entre el género y el poder en los casos de ruptura conyugal

  8. Study of proton-deuteron break-up reaction in exclusive experiment at 1 GeV

    International Nuclear Information System (INIS)

    Aleshin, N.P.; Belostotskij, S.L.; Dotsenko, Yu.V.

    1987-07-01

    The exclusive proton-deuteron break-up reaction pD yields ppn was studied at 1 GeV. Differential cross sections and polarizations of the final protons were measured in the range of neutron-spectator momenta 0 3 3 <0.2 GeV/c, respectively. The data obtained are well described within the framework of impulse approximation with the Paris wave function of the deuteron. (author)

  9. The NASA Ames Hypervelocity Free Flight Aerodynamic Facility: Experimental Simulation of the Atmospheric Break-Up of Meteors

    Science.gov (United States)

    Wilder, M. C.; Bogdanoff, D. W.

    2015-01-01

    The Hypervelocity Free Flight Aerodynamic Facility at NASA Ames Research Center provides a potential platform for the experimental simulation of meteor breakup at conditions that closely match full-scale entry condition for select parameters. The poster describes the entry environment simulation capabilities of the Hypervelocity Free Flight Aerodynamic Facility (HFFAF) at NASA Ames Research Center and provides example images of the fragmentation of a hypersonic projectile for which break-up was initiated by mechanical forces (impact with a thin polymer diaphragm).

  10. The Break Up: Evaluation of an Anti-Smoking Educational Campaign for Lesbians, Gays, and Bisexuals in Los Angeles County.

    Science.gov (United States)

    Plant, Aaron; Montoya, Jorge A; Tyree, Rachel; Aragon, Linda; Weber, Mark; Le Veque, Matthew; Anderson, Christopher M; Soler, Robin E; Kent, Charlotte

    2017-01-01

    Lesbian, gay, and bisexual (LGB) adults in the United States have a higher prevalence of smoking than their heterosexual counterparts. In 2013, the Los Angeles County Department of Public Health launched a social marketing and outreach campaign called Break Up to reduce the prevalence of smoking in LGB communities. Break Up was evaluated using cross-sectional, street-intercept surveys before and near the end of campaign. Surveys measured demographics, campaign awareness, and self-reported smoking-related outcomes. Bivariate statistics and logistic regression models were used to identify whether campaign awareness was associated with smoking-related outcomes. Calls by LGB persons to a smokers' helpline were also measured. Among those interviewed at endline, 32.7% reported Break Up awareness. Awareness was associated with thinking of quitting smoking and ever taking steps to quit but not with smoking cessation (defined as not smoking in the past 30 days among those who had smoked in the past 6 months). There was a 0.7% increase in the percentage of weekly calls by LGB persons to the helpline in the year after the campaign. Break Up reached about a third of its intended audience. The campaign was associated with smoking cessation precursors and may have led to an increase in helpline utilization, but there is no evidence it affected quit attempts. This study adds to the limited literature on tobacco programs for LGB persons and, as far as we know, is one of the first to evaluate tobacco-free social marketing in this important yet understudied population.

  11. Effects of viscoelasticity on droplet dynamics and break-up in microfluidic T-Junctions: a lattice Boltzmann study.

    Science.gov (United States)

    Gupta, Anupam; Sbragaglia, Mauro

    2016-01-01

    The effects of viscoelasticity on the dynamics and break-up of fluid threads in microfluidic T-junctions are investigated using numerical simulations of dilute polymer solutions at changing the Capillary number (Ca), i.e. at changing the balance between the viscous forces and the surface tension at the interface, up to Ca ≈ 3×10(-2). A Navier-Stokes (NS) description of the solvent based on the lattice Boltzmann models (LBM) is here coupled to constitutive equations for finite extensible non-linear elastic dumbbells with the closure proposed by Peterlin (FENE-P model). We present the results of three-dimensional simulations in a range of Ca which is broad enough to characterize all the three characteristic mechanisms of break-up in the confined T-junction, i.e. squeezing, dripping and jetting regimes. The various model parameters of the FENE-P constitutive equations, including the polymer relaxation time τP and the finite extensibility parameter L2, are changed to provide quantitative details on how the dynamics and break-up properties are affected by viscoelasticity. We will analyze cases with Droplet Viscoelasticity (DV), where viscoelastic properties are confined in the dispersed (d) phase, as well as cases with Matrix Viscoelasticity (MV), where viscoelastic properties are confined in the continuous (c) phase. Moderate flow-rate ratios Q ≈ O(1) of the two phases are considered in the present study. Overall, we find that the effects are more pronounced in the case with MV, as the flow driving the break-up process upstream of the emerging thread can be sensibly perturbed by the polymer stresses.

  12. Energy expenditure and heart rate response to breaking up sedentary time with three different physical activity interventions.

    Science.gov (United States)

    Carter, S E; Jones, M; Gladwell, V F

    2015-05-01

    Prolonged sedentary behaviour is associated with increased cardiovascular disease risk and decreased energy expenditure (EE). Workplace interventions breaking up sedentary time have increased EE but the cardiovascular responses are unknown. The practicalities of these interventions, such as required costs and workplace adaptations, are questioned. Calisthenics exercises overcome such limitations, but have not been assessed. The aim of this study was to assess the EE and heart rate (HR) response when breaking up sedentary time with a short bout of standing, walking or calisthenics. Twenty healthy participants (15 male) completed four 30 min conditions: a) 30 min sitting, or breaking up this period with two minutes of b) standing, c) treadmill walking (4 km·h(-1)) or d) a set of calisthenics exercises (including squats and lunges). HR and EE (indirect calorimetry) were assessed throughout. During the activity break, calisthenics caused the highest HR (90 ± 12 bpm) compared to all other conditions (Sit: 70 ± 12 bpm; Stand:72 ± 13 bpm; Walk:84 ± 10 bpm; p sedentary time without individuals leaving their work environment. Hence calisthenics could be utilised to disrupt workplace sedentary time and improve cardiovascular health and assist in weight management. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Electron and ion induced electron emission from metals and insulators

    CERN Document Server

    Steinbatz, M

    2001-01-01

    gradually exposed to oxygen as an experimental probe. The experimental data are fitted with an analytical model, that is able to describe the observed kinetics. The fit parameters give absolute values of sticking probabilities and of surface reaction rates. During oxidation of aluminum and magnesium also spontaneous emission of electrons (exoelectrons) is observed. This effect is quantitatively studied for different oxygen partial pressures. The experimental data also indicate a significant influence of the surface morphology on the exoemission process. An important consequence of atomic collisions in solids is ionization leading to electron ejection from the target atoms with subsequent migration through the solid. A certain fraction of these electrons finally reaches the surface and is ejected into vacuum. A standard measurement of this phenomenon is the observation of the particle (electron, ion) induced electron emission yield g, defined as the average number of ejected electrons per incoming projectile. ...

  14. Evaluation of the UP4FUN Intervention: A Cluster Randomized Trial to Reduce and Break Up Sitting Time in European 10-12-Year-Old Children

    NARCIS (Netherlands)

    Vik, F.N.; Lien, N.; Berntsen, S.; de Bourdeaudhuij, I.; Grillenberger, M.; Manios, Y.; Kovacs, E.; Chin A Paw, M.J.M.; Brug, J.; Bere, E.

    2015-01-01

    Background: The UP4FUN intervention is a family-involved school-based intervention aiming at reducing and breaking up sitting time at home (with special emphasis on screen time), and breaking up sitting time in school among 10-12 year olds in Europe. The purpose of the present paper was to evaluate

  15. Magma-Assisted Continental Break-up Encroached on Previously Stretched Continental Lithosphere - the NE Greenland Composite Passive Margin

    Science.gov (United States)

    Mazur, S.; Rippington, S.; Houghton, P.

    2014-12-01

    Volcanic continental margins have a number of distinctive features that are different from those typical of magma-poor continental margins. However, in some places volcanic margins may develop parallel to older, highly extended rift systems. In such situations the resultant continental margin shows a complex structure that merges the characteristics of volcanic and non-volcanic margins. Furthermore, the evolution of this younger magma-rich margin is restricted by the pre-existing lithospheric architecture, causing it to diverge from the generally assumed formation model. We use the case of NE Greenland to demonstrate the structure of a composite margin firstly subjected to extensive extension and later overprinted by magma-assisted continental break-up. The NE Greenland continental margin is a highly extended margin, that is up to 250km wide, with crystalline crust attaining the maximum thickness near to the coast of Greenland and at the Danmarkshaven Ridge. The latter represents a major basement horst formed during an Early Cretaceous rifting event. To the east of the Danmarkshaven Ridge, crust is stretched and onlapped by the Early Cretaceous sedimentary basin. The effects of Tertiary break-up are observable in a relatively narrow zone 80 km wide that usually includes an extended edge of continental crust and an adjacent section of oceanic crust. A volcano-sedimentary succession produced during the break-up reaches the maximum thickness of c. 8000 m above a continent-ocean transition (COB). Oceanic crust overlain by mixed volcanic and sedimentary rocks is thicker than usual. No observable SDRs or igneous transitional crust are present near to the COB. Instead, a chain of high density bodies follow the COB at the base of crust. The features observed suggest relatively little extension associated with the Tertiary break-up. Instead localised mantle melting presumably led to rapid break-up with crustal dilatation promptly balanced by production of thick oceanic

  16. A Model of the Bubble Break-up in a Turbulent Flow; Modelizacion de la rotura de una Burbuja en un Flujo Turbulento

    Energy Technology Data Exchange (ETDEWEB)

    Bayod, R.; Rodriguez Rodriguez, J.; Martinez Bazan, C.

    2005-07-01

    In this report, a simplified model of the break-up of an air bubble in a turbulent water flow is proposed and analyzed numerically. According to Hinze's theory, and our experimental observations, the external flow field is assumed asymmetric and irrotational for away from the bubble. furthermore the turbulent flow-field is modelled by an asymmetric hyperbolic flow-field and the evolution of the air-water interface is calculated by the levels-set method for a wide range of Reynolds and Weber numbers. Therefore, the break-up times are obtained for super-critical weber numbers and different Reynolds numbers. Therefore, the break-up times are obtained for super-critical Weber and Reynolds numbers allows the comparison of the numeric with our experimental results. Other possible break-up mechanisms for subcritical Weber number, i. e. the break-up by resonance, are also considered. (Author) 20 refs.

  17. Effects of breaking up prolonged sitting following low and high glycaemic index breakfast consumption on glucose and insulin concentrations.

    Science.gov (United States)

    Bailey, Daniel P; Maylor, Benjamin D; Orton, Charlie J; Zakrzewski-Fruer, Julia K

    2017-07-01

    Breaking up prolonged sitting can attenuate the postprandial rise in glucose and insulin. Whether such effects are dependent of the glycaemic index (GI) of the consumed carbohydrate is unknown. This study examined the acute effects of breaking up prolonged sitting following a low GI and a high GI breakfast on postprandial glucose and insulin concentrations. Fourteen adult males aged 22.1 ± 1.2 years completed four, 4 h experimental conditions: high GI breakfast followed by uninterrupted sitting (HGI-SIT), low GI breakfast followed by uninterrupted sitting (LGI-SIT), high GI breakfast followed by 2 min activity breaks every 20 min (HGI-ACT), and low GI breakfast followed by 2 min activity breaks every 20 min (LGI-ACT). Positive incremental area under the curve (iAUC) for glucose and insulin (mean [95% CI]) for each 4 h experimental condition was calculated. Statistical analyses were completed using linear mixed models. The sitting × breakfast GI interaction was not significant for glucose positive iAUC (P = 0.119). Glucose positive iAUC (mmol/L 4 h -1 ) was significantly lower in the activity breaks conditions than the uninterrupted sitting conditions (2.07 [2.24, 2.89] vs. 2.56 [1.74, 2.40], respectively, P = 0.004) and significantly lower in the low GI conditions than the high GI conditions (2.13 [1.80, 2.45] vs. 2.51 [2.18, 2.84], respectively, P = 0.022). Insulin concentrations did not differ between conditions (P ≥ 0.203). Breaking up prolonged sitting and lowering breakfast GI independently reduced postprandial glucose responses. This indicates that interrupting prolonged sitting and reducing dietary GI are beneficial approaches for reducing cardiometabolic disease risk.

  18. Noninvasive Keratograph assessment of tear film break-up time and location in patients with age-related cataracts and dry eye syndrome.

    Science.gov (United States)

    Jiang, Yongxiang; Ye, Hongfei; Xu, Jianjiang; Lu, Yi

    2014-04-01

    To investigate tear-film break-up time and spatial distribution via noninvasive Keratograph 4 in patients with cataracts and dry eye syndrome (DES). Noninvasive first break-up time (NIKf-BUT) and average break-up time (NIKav-BUT) were evaluated via Keratograph 4 in patients with age-related cataracts and DES. The location and size of tear break regions were recorded and the distribution of first break-up areas was summarized. Patients also underwent conventional break-up time assessments (TBUT test and Schirmer's test). A total of 43 left and 43 right eyes were examined. There was no significant difference between TBUT and NIKav-BUT. NIKf-BUT was significantly shorter than TBUT. Both NIKf-BUT and NIKav-BUT correlated positively with TBUT. In both the left and right eye, the most common first break-up areas were the peripheral domain of the inferior precorneal surface and the central domain of the superior portion. The Keratograph 4 appears to provide an effective noninvasive method for assessing tear film, enabling effective preoperative evaluation of tear film break-up regularity, informing the location of the incision and reducing the probability of postoperative DES.

  19. Application of the Constrained Admissible Region Multiple Hypothesis Filter to Initial Orbit Determination of a Break-up

    Science.gov (United States)

    Kelecy, Tom; Shoemaker, Michael; Jah, Moriba

    2013-08-01

    A break-up in Low Earth Orbit (LEO) is simulated for 10 objects having area-to-mass ratios (AMR's) ranging from 0.1-10.0 m2/kg. The Constrained Admissible Region Multiple Hypothesis Filter (CAR-MHF) is applied to determining and characterizing the orbit and atmospheric drag parameters (CdA/m) simultaneously for each of the 10 objects with no a priori orbit or drag information. The results indicate that CAR-MHF shows promise for accurate, unambiguous and autonomous determination of the orbit and drag states.

  20. Particle aerosolisation and break-up in dry powder inhalers 1: evaluation and modelling of venturi effects for agglomerated systems.

    Science.gov (United States)

    Wong, William; Fletcher, David F; Traini, Daniela; Chan, Hak-Kim; Crapper, John; Young, Paul M

    2010-07-01

    This study utilized a combination of computational fluid dynamics (CFD) and standardized entrainment tubes to investigate the influence of turbulence on the break-up and aerosol performance of a model inhalation formulation. Agglomerates (642.8 mum mean diameter) containing 3.91 mum median diameter primary spherical mannitol particles were prepared by spheronisation. A series of entrainment tubes with different Venturi sections were constructed in silico, and the flow pattern and turbulence/impaction parameters were predicted using CFD. The entrainment models were constructed from the in silico model using three-dimensional printing. The aerosol performance of the mannitol was assessed by entraining the agglomerates into the experimental tubes at a series of flow rates and assessing the size distribution downstream of the venturi via in-line laser diffraction. A series of parameters (including Reynolds number (Re), turbulence kinetic energy, turbulence eddy frequency, turbulence length-scale, velocity and pressure drop) were calculated from the CFD simulation. The venturi diameter and volumetric flow rate were varied systematically. The particle size data of the agglomerated powders were then correlated with the CFD measurements. No correlation between turbulence and aerosol performance could be made (i.e. at a Reynolds number of 8,570, the d(0.1) was 52.5 mum +/- 19.7 mum, yet at a Reynolds number of 12,000, the d(0.1) was 429.1 mum +/- 14.8 mum). Lagrangian particle tracking indicated an increase in the number of impactions and the normal velocity component at the wall, with increased volumetric airflow and reduced venturi diameter. Chemical analysis of the mannitol deposited on the walls showed a linear relationship with respect to the theoretical number of impactions (R(2) = 0.9620). Analysis of the relationship between the CFD results and the experimental size data indicated a critical impact velocity was required to initiate agglomerate break-up

  1. Design consideration of relativistic klystron two-beam accelerator for suppression of beam-break-up

    International Nuclear Information System (INIS)

    Li, H.; Houck, T.L.; Yu, S.; Goffeney, N.

    1994-03-01

    It is demonstrated in this simulation study that by using the scheme of operating rf extraction structures on the betatron nodes of electron drive beam in conjunction with adequate de-Q-ing, appropriate choice of geometries for the rf structures (reducing transverse impedence) and/or staggered tuning we can suppress the overall growth of transverse instabilities to 4 e-folds in a relativistic klystron two-beam accelerator with 200 extraction cavities

  2. Low pressure gas detectors for molecular-ion break up studies

    International Nuclear Information System (INIS)

    Breskin, A.; Chechik, R.; Zwang, N.

    1981-01-01

    Two detector systems for Molecular ions like OH + and CH 2 + and like H 2 + and H 3 + were developed and are described. The first detector is installed in a magnetic spectrometer. Both systems are made of various types of gas detectors operating at low pressures. In the study of the Coulomb explosion of molecular ions like OH + , CH 2 + or H 3 + these detectors provide the position and time coordinates of all the fragments of the molecular ion, in coincidence, in order to determine their energy and angular distribution. In the case of molecules containing atoms other than hydrogen, information on the electronic charge state is obtained. (H.K.)

  3. Marital satisfaction and break-ups differ across on-line and off-line meeting venues.

    Science.gov (United States)

    Cacioppo, John T; Cacioppo, Stephanie; Gonzaga, Gian C; Ogburn, Elizabeth L; VanderWeele, Tyler J

    2013-06-18

    Marital discord is costly to children, families, and communities. The advent of the Internet, social networking, and on-line dating has affected how people meet future spouses, but little is known about the prevalence or outcomes of these marriages or the demographics of those involved. We addressed these questions in a nationally representative sample of 19,131 respondents who married between 2005 and 2012. Results indicate that more than one-third of marriages in America now begin on-line. In addition, marriages that began on-line, when compared with those that began through traditional off-line venues, were slightly less likely to result in a marital break-up (separation or divorce) and were associated with slightly higher marital satisfaction among those respondents who remained married. Demographic differences were identified between respondents who met their spouse through on-line vs. traditional off-line venues, but the findings for marital break-up and marital satisfaction remained significant after statistically controlling for these differences. These data suggest that the Internet may be altering the dynamics and outcomes of marriage itself.

  4. PAES: Positron annihilation induced Auger electron spectrometer

    Directory of Open Access Journals (Sweden)

    Christoph Hugenschmidt

    2015-08-01

    Full Text Available Positron annihilation induced Auger electron spectroscopy (PAES is a newly developed application for surface studies with high elemental selectivity and exceptional surface sensitivity. The instrument is operated by the Technische Universität München and is located at NEPOMUC.

  5. Cumulative beam break-up study of the spallation neutron source superconducting linac

    CERN Document Server

    Jeon, D; Krafft, G A; Yunn, B; Sundelin, R; Delayen, J; Kim, S; Doleans, M

    2002-01-01

    Beam instabilities due to High Order Modes (HOMs) are a concern to superconducting (SC) linacs such as the Spallation Neutron Source (SNS) linac. The effects of pulsed mode operation on transverse and longitudinal beam breakup instability are studied for H sup - beam in a consistent manner for the first time. Numerical simulation indicates that cumulative transverse beam breakup instabilities are not a concern in the SNS SC linac, primarily due to the heavy mass of H sup - beam and the HOM frequency spread resulting from manufacturing tolerances. As little as +-0.1 MHz HOM frequency spread stabilizes all the instabilities from both transverse HOMs, and also acts to stabilize the longitudinal HOMs. Such an assumed frequency spread of +-0.1 MHz HOM is small, and hence conservative compared with measured values of sigma=0.00109(f sub H sub O sub M -f sub 0)/f sub 0 obtained from Cornell and the Jefferson Lab Free Electron Laser cavities. However, a few cavities may hit resonance lines and generate a high heat lo...

  6. Radiation-induced electron migration along DNA

    International Nuclear Information System (INIS)

    Fuciarelli, A.F.; Sisk, E.C.; Miller, J.H.; Zimbrick, J.D.

    1994-04-01

    Radiation-induced electron migration along DNA is a mechanism by which randomly produced stochastic energy deposition events can lead to nonrandom types of damage along DNA manifested distal to the sites of the initial energy deposition. Electron migration along DNA is significantly influenced by the DNA base sequence and DNA conformation. Migration along 7 base pairs in oligonucleotides containing guanine bases was observed for oligonucleotides irradiated in solution which compares to average migration distances of 6 to 10 bases for Escherichia coli DNA irradiated in solution and 5.5 base pairs for Escherichia coli DNA irradiated in cells. Evidence also suggests that electron migration can occur preferentially in the 5' to 3' direction along DNA. Our continued efforts will provide information regarding the contribution of electron transfer along DNA to formation of locally multiply damaged sites created in DNA by exposure to ionizing radiation

  7. Positron annihilation induced Auger electron spectroscopy

    Science.gov (United States)

    Weiss, Alex; Koymen, A. R.; Mehl, David; Jensen, K. O.; Lei, Chun; Lee, K. H.

    1990-01-01

    Recently, Weiss et al. have demonstrated that it is possible to excite Auger transitions by annihilating core electrons using a low energy (less than 30eV) beam of positrons. This mechanism makes possible a new electron spectroscopy, Positron annihilation induced Auger Electron Spectroscopy (PAES). The probability of exciting an Auger transition is proportional to the overlap of the positron wavefunction with atomic core levels. Since the Auger electron energy provides a signature of the atomic species making the transition, PAES makes it possible to determine the overlap of the positron wavefunction with a particular element. PAES may therefore provide a means of detecting positron-atom complexes. Measurements of PAES intensities from clean and adsorbate covered Cu surfaces are presented which indicate that approx. 5 percent of positrons injected into CU at 25eV produce core annihilations that result in Auger transitions.

  8. Energy spectra of protons in diffraction break-up of deuterons on 12C and 40Ca at intermediate energies

    Directory of Open Access Journals (Sweden)

    V. V. Davydovskyy

    2016-08-01

    Full Text Available In the diffraction approximation generalized to the case of inelastic processes with longitudinal momentum transfer, the reaction of the deuteron break-up on nuclei at medium energies is studied, taking into account the Coulomb and nuclear interactions. The formulas for the calculation of the energy spectra of the emerging protons are obtained up to the second order with respect to the ratio of the deuteron radius to the nucleus radius. Three types of model wave functions of the deuteron were used in the calculations: Yukawa, exponential and Gaussian. The wave function of np-pair in continuum is built orthogonal to the wave function of deuteron. This allows one to take into account qualitatively the interaction in the final state and avoid false contributions to the cross section at near zero momentum transfer. A comparison with experimental data on the break-up of deuterons with energy of 56 MeV on carbon and calcium with the registration of the emitted neutrons and protons at zero angles is carried out. It is shown that the contribution of the Coulomb mechanism dominates in the cross section. The best description of the spectra of protons is achieved by using the Yukawa form of the wave function of the deuteron. It is also shown that taking into account the transfer of longitudinal momentum to the deuteron nucleons improves the experimental data description. In the case of non-zero nucleon escape angles, the effect of taking into account longitudinal momentum can reach several hundred percent.

  9. Constraining the role of magma before, during and after the break-up of continents using seismic reflection data

    Science.gov (United States)

    Magee, C.; Jackson, C. A. L.; Schofield, N.; Holford, S. P.

    2014-12-01

    The ability to visualize networks of igneous intrusions in 3D using seismic reflection data has revolutionized our understanding of how magma migrates and is emplaced during continental breakup. Numerous seismic-based studies have shown that: (i) sub-horizontal or saucer-shaped sill intrusions represent a major component of magmatic systems within sedimentary basins; (ii) these sills may be interconnected to form laterally extensive (>100's km2) sill-complexes; (iii) magma flow indicators can be mapped within the sills to reconstruct magma migration routes and source positions; (iv) space-making mechanisms (e.g., forced folds) can be identified, which provide constraints on intrusive style (e.g., brittle or non-brittle); and (v) cross-cutting and seismic-stratigraphic relationships between the sills and host rock can be used to constrain the age of igneous activity. We use a series of seismic data, primarily from the Rockall Basin, NE Atlantic and offshore Australia, to demonstrate how the observations described above can be synthesized to reconstruct the evolution of ancient magmatic systems located along continental volcanic rifted margins. Our results demonstrate that the architecture of such intrusive networks is significantly influenced by the pre-existing structure and lithology of the host rock. Importantly, relatively dating the intrusive and extrusive components of magmatic systems suggests igneous activity may occur more intermittently and over longer time periods than previously thought, potentially spanning entire break-up histories. Overall, seismic reflection data provide important insights into: (i) the role of magma before, during and after continental break-up; and (ii) the influence of crystallised intrusion networks on subsequent basin evolution and fluid flow processes.

  10. Revised model of the East Gondwana Break-up and formation of the Gateway between India and Antarctica

    Science.gov (United States)

    Leitchenkov, German; Guseva, Julia; Ivanov, Sergey; Golynsky, Alexander

    2017-04-01

    The history of break-up and sea-floor spreading between India and Antarctica long remained vague mainly because of the data scarcity off both continents. Geophysical studies carried out recently in the Enderby Basin (Southern Indian Ocean) provided new information and advanced our knowledge on this problem. Magnetic surveys discovered there a prominent linear high-amplitude bipolar magnetic anomaly (HBMA), which stretched more than 1000 km westward from the southern Kerguelen Plateau. This anomaly was interpreted by many as the contact between stretched continental crust and oceanic crust. Gaina et al. (1987) suggested the existence of an abandoned spreading centre in the eastern Enderby Basin and inferred that the Elan Bank (established as a microcontinent) was isolated from the India margin by a ridge jump at about M0 chron (c. 120 Ma). South of an abandoned spreading centre, they identified a series of magnetic anomalies from M2 to M9. New magnetic data collected in the western Enderby Basin and revision of all available geophysical data gives a new notion on the geodynamics of the East Gondwana break-up and separation of India from Antarctica. According to a new model, the HBMA corresponds to M34o chrone and its increased intensity can be explained by the emplacement of the Kerguelen Hotspot and thickening of the oceanic (magmatic) crust at that time. A relationship between hot-spots and appearance of high-amplitude magnetic anomalies is observed elsewhere in the World Ocean. In our model, the continent-ocean boundary is located about 150 km landward of the HBMA, and anomalies from M4 to M0 are identified between these features. The ridge jump (which isolated the Elan Bank) occurred about 110 Ma ago when the Kerguelen Hotspot moved toward the India margin. This model is consistent with the interpretation of sea-floor spreading history off Western Australia. An earlier (around 120 Ma) ridge jump probably occurred in the area of the southern Kerguelen Plateau

  11. Evaluation of the UP4FUN intervention: a cluster randomized trial to reduce and break up sitting time in European 10-12-year-old children.

    Directory of Open Access Journals (Sweden)

    Frøydis N Vik

    Full Text Available The UP4FUN intervention is a family-involved school-based intervention aiming at reducing and breaking up sitting time at home (with special emphasis on screen time, and breaking up sitting time in school among 10-12 year olds in Europe. The purpose of the present paper was to evaluate its short term effects.A total of 3147 pupils from Belgium, Germany, Greece, Hungary and Norway participated in a school-randomized controlled trial. The intervention included 1-2 school lessons per week for a period of six weeks, along with assignments for the children and their parents. Screen time and breaking up sitting time were registered by self-report and total sedentary time and breaking up sitting time by accelerometry. The effect of the intervention on these behaviors was evaluated by multilevel regression analyses. All analyses were adjusted for baseline values and gender. Significance level was p≤0.01. No significant intervention effects were observed, neither for self-reported TV/DVD or computer/game console time, nor for accelerometer-assessed total sedentary time and number of breaks in sitting time. The intervention group, however, reported more positive attitudes towards (β = 0.25 (95% CI 0.11, 0.38 and preferences/liking for (β = 0.20 (95% CI 0.08, 0.32 breaking up sitting time than the control group.No significant intervention effect on self-reported screen time or accelerometer-assessed sedentary time or breaks in sitting time was observed, but positive effects on beliefs regarding breaking up sitting time were found in favor of the intervention group. Overall, these results do not warrant wider dissemination of the present UP4FUN intervention.International Standard Randomized Controlled Trial Number Registry ISRCTN34562078.

  12. Movement of a female polar bear (Ursus maritimus) in the Kara Sea during the summer sea-ice break-up.

    Science.gov (United States)

    Rozhnov, V V; Platonov, N G; Naidenko, S V; Mordvintsev, I N; Ivanov, E A

    2017-01-01

    The polar bear movement trajectory in relation to onset date of the sea-ice break-up was studied in the coastal zone of the Taimyr Peninsula, eastern part of the Kara Sea, using as an example a female polar bear tagged by a radio collar with an Argos satellite transmitter. Analysis of the long-term pattern of ice melting and tracking, by means of satellite telemetry, of the female polar bear who followed the ice-edge outgoing in the north-eastern direction (in summer 2012) suggests that direction of the polar bear movement depends precisely on the direction of the sea-ice cover break-up.

  13. Spring phytoplankton onset after the ice break-up and sea-ice signature (Adélie Land, East Antarctica)

    OpenAIRE

    Riaux-Gobin, C.; Poulin, M.; Dieckmann, Gerhard; Labrune, C.; Vétion, G.

    2011-01-01

    The phytoplankton onset following the spring ice break-up in Adélie Land, East Antarctica, was studied along a short transect, from 400 m off the continent to 5 km offshore, during the austral summer of 2002. Eight days after the ice break-up, some large colonial and solitary diatom cells, known to be associated with land-fast ice and present in downward fluxes, were unable to adapt in ice-free waters, while some other solitary and short-colony forming taxa (e.g., Fragilariopsis curta, F. cyl...

  14. Biomimetic Interfacial Electron-Induced Electrochemiluminesence.

    Science.gov (United States)

    Pu, Guiqiang; Zhang, Dongxu; Mao, Xiang; Zhang, Zhen; Wang, Huan; Ning, Xingming; Lu, Xiaoquan

    2018-04-17

    We provide here, for the first time, a new interfacial electron-induced electrochemiluminescence (IEIECL) system, realizing bionic construction of bioluminescence (BL) by exploiting electrochemiluminescence (ECL) and ITIES (the interface between two immiscible electrolyte solutions). Significantly, the superiority of the IEIECL system is embodied with the solution of the two bottlenecks encountered in the conventional ECL innovation: that are (a) the applications of hydrophobic luminophores in more commonly used aqueous solution are inhibited tremendously due to the poor inherent solubility and the instability of radicals and (b) the analytes, insoluble in water, are hard to be discovered in an aqueous system because of too little content. More productive IEIECL radiation, analogous to BL, originates from the triplet excited state porphyrin in comparison to the homogeneous ECL. The mechanism of IEIECL, as well as the interaction mechanism between IEIECL and charge transfer (comprising electron transfer (ET), ion transfer (IT), and facilitated ion transfer (FIT)) at the ITIES, are explored in detail. Finally, we emphasize the actual application potential of the IEIECL system with the detection of cytochrome c (Cyt c); it is a key biomolecule in the electron transport chain in the process of biological oxidation and is also an intermediate species in apoptosis. Potentially, the IEIECL system permits ones to explore the lifetime and diffusion path of free radicals, as well as imparting a possibility for the construction of a bionic sensor.

  15. Randomized controlled pilot of an intervention to reduce and break-up overweight/obese adults' overall sitting-time.

    Science.gov (United States)

    Júdice, Pedro B; Hamilton, Marc T; Sardinha, Luís B; Silva, Analiza M

    2015-11-02

    Too much prolonged sitting is a prevalent health risk among adults. Interventions have focused mainly on the workplace, with limited attention to non-work settings. The effectiveness of a short-term intervention to reduce and break-up sitting-time in overweight/obese adults was examined. This pilot study sought to determine the feasibility of interrupting sitting to stand/ambulate objectively with ActivPAL devices which provide a valid measurement of sit/stand transitions. This is a cross-over randomized controlled pilot that included 10 participants (aged 37-65 years) and although a small and short-term intervention (1-week intervention; no washout) further informs on the feasibility of interventions on a larger scale. At the workplace, screen-delivered hourly alerts prompted participants to break-up sitting-time through adopting walking behaviors (approximately 30-60 minutes day(-1)). During transportation/home/leisure-time individual goals for steps day(-1) were set and sitting-reduction strategies (including behavioral self-monitoring) were delivered through daily text messages. Change in inclinometer-derived sitting-time is the main outcome. Standing, stepping, number of sit/stand transitions and participant satisfaction were also examined. For the intervention compared to the control-week (mean difference (95 % confidence interval); p value), participants had less sitting-time (1.85 hours (0.96-2.75); p = 0.001), more standing (0.77 hours (0.06-1.48); p = 0.036), and more stepping (1.09 hours (0.79- 1.38); p change in the total number of sit/stand transitions (3.28 (-2.33-8.89); p = 0.218) despite successfully reducing sitting-time and increasing time spent standing and walking. Sitting-time in overweight/obese adults can be reduced following a brief multi-component intervention based on prompts, telephone support, goal setting and behavioral self-monitoring. However, the results from this pilot study provide new insight that when overweight

  16. The Relationship Between Tear Ferning Patterns and Non-invasive Tear Break-up Time in Normal Asian Population.

    Science.gov (United States)

    Sharanjeet-Kaur; Ho, Chien Yee; Mutalib, Haliza Abdul; Ghazali, Ahmad Rohi

    2016-01-01

    To investigate the relationship between tear ferning patterns (TFP) and non-invasive tear break-up time (NIBUT) in normal Asian subjects. One hundred and forty-five adults with no ocular surface disorders were recruited. TFP and NIBUT were determined. Tears were collected using a capillary tube and allowed to air dry at room temperature for 10min. TFP was later observed using a light microscope and classified according to Rolando's classification. Measurement for NIBUT was obtained using a Tearscope with the slit lamp magnification. It was found that there is no significant difference between gender in TFP (Z=-1.77, P>.05) and NIBUT (Z=-1.475, P>.05). There is also no significant difference between Malay, Chinese, Indian, and other races in TFP, (H(3)=4.85, P>.05) and NIBUT (H(3)=2.18, P>.05). However, there is a significant difference between age groups of 20-29, 30-39, 40-49,and 50-60 years old in both TFP (H(3)=28.25, P<.01) and NIBUT (H(3)=36.50, P<.001). Spearman's correlation showed there was a significant relationship between TFP and NIBUT (r=-0.55, P<.001), age and NIBUT (r=-0.50, P<.001), age and TFP (r=0.41, P<.001), McMonnies score and NIBUT (r=-0.40, P<.001), McMonnies score and TFP (r=0.31, P<.001), as well as age and McMonnies score (r=0.52, P<.001). TFP and NIBUT was age dependent but not gender and race dependent. Older subjects had higher grade of TFP and McMonnies questionnaire score but lower NIBUT value. TFP and NIBUT can be used to assess the tear film quality. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  17. Electron-induced excitation of 93Mo

    Science.gov (United States)

    Chiara, C. J.; Carroll, J. J.; Marsh, J. C.; Matters, D. A.; Lane, G. J.; Hartley, D. J.; Polasik, M.; Rzadkiewicz, J.; Carpenter, M. P.; Greene, J. P.; Janssens, R. V. F.; Seweryniak, D.; Zhu, S.

    2016-09-01

    The inverse of the internal-conversion process, whereby a free electron is captured into an atomic orbital and subsequently excites the nucleus to a higher-lying state via a virtual energy exchange, was predicted to exist 40 years ago but has yet to be demonstrated experimentally. To search for this mode of nuclear excitation by electron capture, we performed an experiment at the ATLAS facility at Argonne National Laboratory. The t1/2 = 6.85-h, 21/2+ state of 93Mo was populated in the 7Li(90Zr, p 3 n) reaction. The excitation mechanism was predicted to induce depopulation of this isomer as the fast-moving 93mMo recoils slowed in the target material, emitting a characteristic sequence of γ rays in the process. Results of the search for these signature γ rays using Digital Gammasphere will be presented. This material is based upon work supported by the US DOE, Office of Science, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. This research used resources of ANL's ATLAS facility, which is a DOE Office of Science User Facility.

  18. Electron-beam induced conduction in some polymers

    International Nuclear Information System (INIS)

    Suzuoki, Yasuo; Mizutani, Teruyoshi; Ieda, Masayuki

    1976-01-01

    The charge signal induced by pulsed electron beam consists of two components, i.e. the fast and the slow components. The slow component which corresponds to carrier transport via shallow traps exhibited an asymmetry with respect to the bias field polarity. The asymmetry revealed that the main carriers which drifted via shallow traps were electrons in PET, both electrons and holes in PEN, and holes in PS. TSC spectra of electron-beam induced electrets proved directly the existence of electron shallow traps in PET and both electron and hole traps in PEN. Their trap energies were 0.1 to 0.2 eV. (auth.)

  19. The Fragmented Manihiki Plateau - Key Region for Understanding the Break-up of the "Super" Large Igneous Province Ontong Java Nui

    Science.gov (United States)

    Hochmuth, K.; Gohl, K.; Uenzelmann-Neben, G.; Werner, R.

    2014-12-01

    The Manihiki Plateau of the western Pacific is one of the world - wide greatest Large Igneous Province (LIP) on oceanic crust. It is assumed that the Manihiki Plateau was emplaced as the centerpiece of the "Super-LIP" Ontong Java Nui by multiple volcanic phases during the Cretaceous Magnetic Quiet Period. The subsequent break-up of Ontong Java Nui led to fragmentation of the Manihiki Plateau into three sub-plateaus, which all exhibit individual relicts of the "Super-LIP" break-up. We examine two deep crustal seismic refraction/wide-angle reflection profiles crossing the two largest sub-plateaus of the Manihiki Plateau, the Western Plateaus and the High Plateau. Modeling of P- and S-wave velocities reveals surprising differences in the crustal structure between the two sub-plateaus. Whereas the High Plateau shows a constant crustal thickness of 20 km, relicts of multiple volcanic phases and break-up features at its margins, the model of the Western Plateaus reveals a crustal thickness decreasing from 17 km to only 9 km. There is only little evidence of secondary phases of volcanic activity. The main upper crustal structure on the Western Plateaus consists of fault systems and sedimentary basins. We infer that the High Plateau experienced phases of strong secondary volcanism, and that tectonic deformation was limited to its edges. The Western Plateaus, on the contrary, were deformed by crustal stretching and underwent only little to no secondary volcanism. This indicates that the two main sub-plateaus of the Manihiki Plateau experienced a different geological history and have played their individual parts in the break-up history of Ontong Java Nui.

  20. Simulations of bubble coalescence and breaking-up using connectivity-free point-set front tracking method with finite element

    Science.gov (United States)

    Wang, Chu; Zhang, Lucy

    2010-11-01

    The capability of handling constant and multi-scale bubble topological changes is essential in modeling and simulating bubble coalescence and breaking up. The traditional front tracking method relies on the connectivity of the interfacial points to calculate the normal and curvature in order to evaluate surface tension. In bubble coalescence and breaking up, such connectivity reconstruction can be quite expensive. In this work, we adopt the point-set method [1] to construct each individual interfacial point without any connectivity. This approach combined with the original front tracking concept allow us to model bubble topological changes automatically. By letting the interface to be at a constant level, the indicator field is smeared out using the quintic B-Spline function. A regeneration method adopting one-dimensional Newton iteration can update the interfacial points in order to cope with the topology change. The interface points are then coupled with a finite element fluid solver to study bubble rising in a channel testing case. The coalescence and breaking up are also simulated to show the advantage of using the point-set method. [4pt] [1] D. J. Torres, J. U. Brackbill, The Point-Set Method: Front-Tracking without Connectivity, J. Comupt. Phys, 2000,165(2):620-644

  1. Ion-induced electron emission microscopy

    Science.gov (United States)

    Doyle, Barney L.; Vizkelethy, Gyorgy; Weller, Robert A.

    2001-01-01

    An ion beam analysis system that creates multidimensional maps of the effects of high energy ions from an unfocussed source upon a sample by correlating the exact entry point of an ion into a sample by projection imaging of the secondary electrons emitted at that point with a signal from a detector that measures the interaction of that ion within the sample. The emitted secondary electrons are collected in a strong electric field perpendicular to the sample surface and (optionally) projected and refocused by the electron lenses found in a photon emission electron microscope, amplified by microchannel plates and then their exact position is sensed by a very sensitive X Y position detector. Position signals from this secondary electron detector are then correlated in time with nuclear, atomic or electrical effects, including the malfunction of digital circuits, detected within the sample that were caused by the individual ion that created these secondary electrons in the fit place.

  2. The role of electron scattering in electron-induced surface chemistry

    NARCIS (Netherlands)

    van Dorp, Willem F.

    2012-01-01

    Electron-induced chemistry on surfaces plays a key role in focused electron beam induced processing (FEBIP), a single-step lithography technique that has increasingly gained interest in the past decade. It is crucial for the understanding and modelling of this process to know the role of the surface

  3. Parallel electron-beam-induced deposition using a multi-beam scanning electron microscope

    NARCIS (Netherlands)

    Post, P.C.; Mohammadi-Gheidari, A.; Hagen, C.W.; Kruit, P.

    2011-01-01

    Lithography techniques based on electron-beam-induced processes are inherently slow compared to light lithography techniques. The authors demonstrate here that the throughput can be enhanced by a factor of 196 by using a scanning electron microscope equipped with a multibeam electron source. Using

  4. Dynamics of Low-Energy Electron Induced Reactions in Condensed

    Science.gov (United States)

    Boyer, Michael; Soe, Chanmyaemyae; Chamberlain, Kristal; Shyur, Yomay; Arumainayagam, Christopher

    2011-03-01

    We present insights into the dynamics of low-energy electron-induced reactions in thin films of methanol (CH3 OH). Low-energy electrons in matter can initiate chemical reactions though electron impact ionization of a molecule, electron impact excitation of a molecule, or through dissociation of a transient negative ion formed by electron attachment to a molecule. Our studies focus on the dynamics by which low-energy electron interaction with condensed methanol initiates chemical reactions which lead to the formation of methoxymethanol (CH3 O CH2 OH) and ethylene glycol (HO CH2 CH2 OH). The results of our post-irradiation temperature programmed desorption experiments indicate that both products can form from irradiating methanol with electrons at subionization energies. In addition, we find evidence that dissociative electron attachment plays a role in the formation of methoxymethanol but not in ethylene glycol.

  5. Ion induced high energy electron emission from copper

    International Nuclear Information System (INIS)

    Ruano, G.; Ferron, J.

    2008-01-01

    We present measurements of secondary electron emission from Cu induced by low energy bombardment (1-5 keV) of noble gas (He + , Ne + and Ar + ) and Li + ions. We identify different potential and kinetic mechanisms and find the presence of high energetic secondary electrons for a couple of ion-target combinations. In order to understand the presence of these fast electrons we need to consider the Fermi shuttle mechanism and the different ion neutralization efficiencies.

  6. Reactions induced by low energy electrons in cryogenic films

    International Nuclear Information System (INIS)

    Bass, A.D.; Sanche, L.

    2003-01-01

    We review recent research on reactions (including dissociation) initiated by low-energy electron bombardment of monolayer and multilayer molecular solids at cryogenic temperatures. With incident electrons of energies below 20 eV, dissociation is observed by the electron stimulated desorption (ESD) of anions from target films and is attributed to the processes of dissociative electron attachment (DEA) and to dipolar dissociation. It is shown that DEA to condensed molecules is sensitive to environmental factors such as the identity of co-adsorbed species and film morphology. The effects of image-charge induced polarization on cross-sections for DEA to CH3Cl are also discussed. Taking as examples, the electron-induced production of CO within multilayer films of methanol and acetone, it is shown that the detection of electronic excited states by high resolution electron energy loss spectroscopy can be used to monitor electron beam damage. In particular, the incident energy dependence of the CO indicates that below 19 eV, dissociation proceeds via the decay of transient negative ions (TNI) into electronically excited dissociative states. The electron induced dissociation of biomolecular targets is also considered, taking as examples the ribose analog tetrahydrofuran and DNA bases adenine and thymine, cytosine and guanine. The ESD of anions from such films also show dissociation via the formation of TNI. In multilayer molecular solids, fragment species resulting from dissociation, may react with neighboring molecules, as is demonstrated in anion ESD measurements from films containing O 2 and various hydrocarbon molecules. X-ray photoelectron spectroscopy measurements reported for electron irradiated monolayers of H 2 O and CF 4 on a Si - H passivated surface further show that DEA is an important initial step in the electron-induced chemisorption of fragment species

  7. Electron beam induced conductivity in 'PET' and 'FEP'

    International Nuclear Information System (INIS)

    Walzade, S.J.; Jog, J.P.; Dake, S.B.; Bhoraskar, S.V.

    1983-01-01

    Electron Beam Induced Conductivity (EBIC), classified into EBIC (bulk) and EBIC (surface) have been measured in PET and FEP respectively. The peculiar oscillatory nature of the induced gain versus beam energy variations is explained in terms of the spatial distributions of the trapping centres near the surface of the polymers. (author)

  8. Electron-beam-induced-current and active secondary-electron voltage-contrast with aberration-corrected electron probes

    Energy Technology Data Exchange (ETDEWEB)

    Han, Myung-Geun, E-mail: mghan@bnl.gov [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Garlow, Joseph A. [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Materials Science and Engineering Department, Stony Brook University, Stony Brook, NY 11794 (United States); Marshall, Matthew S.J.; Tiano, Amanda L. [Department of Chemistry, Stony Brook University, Stony Brook, NY 11974 (United States); Wong, Stanislaus S. [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Department of Chemistry, Stony Brook University, Stony Brook, NY 11974 (United States); Cheong, Sang-Wook [Department of Physics and Astronomy, Rutgers Center for Emergent Materials, Rutgers University, Piscataway, NJ 08854 (United States); Walker, Frederick J.; Ahn, Charles H. [Department of Applied Physics and Center for Research on Interface Structures and Phenomena, Yale University, New Haven, CT 06520 (United States); Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT 06520 (United States); Zhu, Yimei [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2017-05-15

    Highlights: • Electron-beam-induced-current (EBIC) and active secondary-electron voltage-contrast (SE-VC) are demonstrated in STEM mode combined with in situ electrical biasing in a TEM. • Electrostatic potential maps in ferroelectric thin films, multiferroic nanowires, and single crystals obtained by off-axis electron holography were compared with EBIC and SE-VC data. • Simultaneous EBIC and active SE-VC performed with atomic resolution STEM are demonstrated. - Abstract: The ability to map out electrostatic potentials in materials is critical for the development and the design of nanoscale electronic and spintronic devices in modern industry. Electron holography has been an important tool for revealing electric and magnetic field distributions in microelectronics and magnetic-based memory devices, however, its utility is hindered by several practical constraints, such as charging artifacts and limitations in sensitivity and in field of view. In this article, we report electron-beam-induced-current (EBIC) and secondary-electron voltage-contrast (SE-VC) with an aberration-corrected electron probe in a transmission electron microscope (TEM), as complementary techniques to electron holography, to measure electric fields and surface potentials, respectively. These two techniques were applied to ferroelectric thin films, multiferroic nanowires, and single crystals. Electrostatic potential maps obtained by off-axis electron holography were compared with EBIC and SE-VC to show that these techniques can be used as a complementary approach to validate quantitative results obtained from electron holography analysis.

  9. Spring phytoplankton onset after the ice break-up and sea-ice signature (Adélie Land, East Antarctica

    Directory of Open Access Journals (Sweden)

    Catherine Riaux-Gobin

    2011-01-01

    Full Text Available The phytoplankton onset following the spring ice break-up in Adélie Land, East Antarctica, was studied along a short transect, from 400 m off the continent to 5 km offshore, during the austral summer of 2002. Eight days after the ice break-up, some large colonial and solitary diatom cells, known to be associated with land-fast ice and present in downward fluxes, were unable to adapt in ice-free waters, while some other solitary and short-colony forming taxa (e.g., Fragilariopsis curta, F. cylindrus did develop. Pelagic species were becoming more abundant offshore, replacing the typical sympagic (ice-associated taxa. Archaeomonad cysts, usually associated with sea ice, were recorded in the surface waters nearshore. Rough weather restricted the data set, but we were able to confirm that some microalgae may be reliable sea-ice indicators and that seeding by sea ice only concerns a few taxa in this coastal area of East Antarctica.

  10. Simulation of condensation and liquid break-up on a micro-object with upper and lower movable walls using Lattice Boltzmann Method

    Science.gov (United States)

    Asadollahi, Arash; Esmaeeli, Asghar

    2018-05-01

    In this paper, two-dimensional condensation, liquid behavior on the micro-object with moving walls, and breaking up have been investigated by the Shan and Chen multiphase Lattice Boltzmann Method (LBM), which has the ability to incorporate interactions such as fluid-fluid, and also fluid-solid. Four test cases with low, medium, high, and very high Weber numbers are investigated considering the velocity control of walls in detail. Vertical spread fraction n / h (where n is the minimum liquid thickness after deformation and h is the maximum length of liquid deformation in each time) decreases quickly indicating the liquid tendency to breakup in all cases. Except for the case of a very high Weber number, the separation will not happen and finally after fluctuation the fixed bulk of condensed liquid will be placed on the side of the micro-object. The maximum value of reaction parameter h / d becomes larger as the Weber number increases. It is shown that an increase in the Weber number leads to liquid breakup and this mechanism provides an effective way for removing the condensed liquid from micro-devices surfaces. The results by LBM reveal the liquid evolutionary behavior and breaking up over time and show that it is a controllable situation by manipulating the walls velocity. Moreover, it can be used in order to centralize and aggregate all the liquid to a specific direction.

  11. Multi-electron beam system for high resolution electron beam induced deposition

    NARCIS (Netherlands)

    Van Bruggen, M.J.

    2008-01-01

    The development of a multi-electron beam system is described which is dedicated for electron beam induced deposition (EBID) with sub-10 nm resolution. EBID is a promising mask-less nanolithography technique which has the potential to become a viable technique for the fabrication of 20-2 nm

  12. Electron-irradiation-induced decomposition of sulfonamides

    Energy Technology Data Exchange (ETDEWEB)

    Liu Zhitao [Department of Engineering Physics, Tsinghua University, Beijing (China)]. E-mail: liuzhitao@tsinghua.org.cn; Zhang Huayi [Department of Engineering Physics, Tsinghua University, Beijing (China)]. E-mail: zhanghuayi@nuctech.com; Shao Bing [Institute of Nutrition and Food Hygiene, Beijing Center for Disease Prevention and Control, Beijing (China); Zhao Rong [Institute of Nutrition and Food Hygiene, Beijing Center for Disease Prevention and Control, Beijing (China)

    2006-11-15

    The effect of electron irradiation on sulfanilamide (SA) and sulfadimethoxine (SDM) solutions has been studied at various irradiation doses and various original concentrations. Upon irradiation at 8 kGy, the concentration of 110 mg/kg SDM decreased by 94%, while 130 mg/kg SA decreased by 99.2%. When exposed to the same dose, The radiolytic products were identified by ultra performance liquid chromatography electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) and the oxidation pathways were proposed.

  13. Electron-irradiation-induced decomposition of sulfonamides

    Science.gov (United States)

    Liu, Zhitao; Zhang, Huayi; Shao, Bing; Zhao, Rong

    2006-11-01

    The effect of electron irradiation on sulfanilamide (SA) and sulfadimethoxine (SDM) solutions has been studied at various irradiation doses and various original concentrations. Upon irradiation at 8 kGy, the concentration of 110 mg/kg SDM decreased by 94%, while 130 mg/kg SA decreased by 99.2%. When exposed to the same dose, The radiolytic products were identified by ultra performance liquid chromatography electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) and the oxidation pathways were proposed.

  14. Direct Imaging by Cryo-TEM Shows Membrane Break-up by Phospholipase A2 Enzymatic Activity

    DEFF Research Database (Denmark)

    Callisen, Thomas Hønger; Talmon, Y.

    1998-01-01

    increase our insight into the function of PLA2 under physiological conditions as well as into general interfacial catalysis. In the present study we apply for the first time cryo-transmission electron microscopy (cryo-TEM) and high-performance liquid chromatography (HPLC) to characterize the PLA2...... hydrolysis of phospholipid vesicles with respect to changes in lipid composition and morphology. Our direct experimental results show that the initial reaction conditions are strongly perturbed during the course of hydrolysis, Most strikingly, cryo-TEM reveals that starting in the lag phase, vesicles become...... perforated and degrade into open vesicles, bilayer fragments, and micelles, This structural instability extends throughout the system in the activity burst regime. In agreement with earlier reported correlations between initial phospholipase activity and substrate morphology, our results suggest that the lag...

  15. Low-Energy Electron Induced Reactions in Condensed Methanol

    Science.gov (United States)

    Boyer, Michael; Boamah, Mavis; Chamberlain, Kristal; Myae Soe, Chanmaye; Bass, Andrew; Sanche, Leon; Arumainayagam, Christopher

    2012-02-01

    We investigate the dynamics of low-energy electron-induced reactions in condensed thin films of methanol (CH3OH) through electron stimulated desorption (ESD) and post-irradiation temperature programmed desorption (TPD) experiments. ESD experiments indicate that the anions which desorb from the methanol thin film during electron irradiation are predominantly formed through the dissociation of temporary negative ions formed by electron capture by methanol molecules, a process known as dissociative electron attachment (DEA). However, based on investigation of reaction products remaining in the methanol thin film post-irradiation through TPD experiments, DEA is not the obvious primary mechanism by which methoxymethanol (CH3OCH2OH) and ethylene glycol (HOCH2CH2OH) are formed. Evidence indicates formation of these molecules may be driven by both DEA and electron impact excitation.

  16. Electron Beam Induced Functionalization of Fluoropolymers

    International Nuclear Information System (INIS)

    Lappan, U.

    2006-01-01

    Ionizing radiation affects the properties of polymers by chain scission and cross-linking reactions. One process will usually predominate, depending on the chemical structure of the polymer and the irradiation conditions such as temperature and atmosphere. Poly(tetrafluoroethylene) (PTFE) and the perfluorinated copolymers poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) and poly(tetrafluoroethylene-co-perfluoropropylvinyl ether) (PFA) undergo predominantly chain scission, if the irradiation is performed at room temperature. This shortcoming is exploited by converting PTFE into low molecular weight micropowders. The irradiation of PTFE in the presence of air results in micropowders functionalized with oxygen-containing groups. The concentration of end groups was investigated by FTIR and 19F solid-state NMR. The data were used to calculate number-average molecular weights. It was demonstrated that PTFE can be cross-linked by irradiation above its crystalline melting temperature in an oxygen-free atmosphere. Evidence for cross-links in PTFE was derived directly from structural information using 19 F solid-state NMR. FEP is understood to undergo cross-linking by irradiation above the glass transition temperature. It was found that also PFA can be branched and cross-linked by irradiation under special conditions. Radiation-induced grafting of styrene into fluoropolymer films and subsequent sulfonation offers an attractive way to prepare proton exchange membranes. Recently, radiation-induced grafting into cross-linked PTFE was reported. Modified FEP, PFA and ETFE films have been used as base material in this study. The modified films have been prepared by irradiation in nitrogen atmosphere at different temperatures up to temperatures above the melting temperature of the fluoropolymer

  17. Photon-induced near-field electron microscopy.

    Science.gov (United States)

    Barwick, Brett; Flannigan, David J; Zewail, Ahmed H

    2009-12-17

    In materials science and biology, optical near-field microscopies enable spatial resolutions beyond the diffraction limit, but they cannot provide the atomic-scale imaging capabilities of electron microscopy. Given the nature of interactions between electrons and photons, and considering their connections through nanostructures, it should be possible to achieve imaging of evanescent electromagnetic fields with electron pulses when such fields are resolved in both space (nanometre and below) and time (femtosecond). Here we report the development of photon-induced near-field electron microscopy (PINEM), and the associated phenomena. We show that the precise spatiotemporal overlap of femtosecond single-electron packets with intense optical pulses at a nanostructure (individual carbon nanotube or silver nanowire in this instance) results in the direct absorption of integer multiples of photon quanta (nhomega) by the relativistic electrons accelerated to 200 keV. By energy-filtering only those electrons resulting from this absorption, it is possible to image directly in space the near-field electric field distribution, obtain the temporal behaviour of the field on the femtosecond timescale, and map its spatial polarization dependence. We believe that the observation of the photon-induced near-field effect in ultrafast electron microscopy demonstrates the potential for many applications, including those of direct space-time imaging of localized fields at interfaces and visualization of phenomena related to photonics, plasmonics and nanostructures.

  18. Electron beam induced heat flow transient in aluminium

    International Nuclear Information System (INIS)

    Dalle Rose, L.F.D.; Brotto, R.

    1983-01-01

    On the basis of a numerically solved heat diffusion equation, the structure of the thermal transient induced in an aluminium sample by an electron beam pulse is described in terms of slush zone formation, molten depth, liquid phase duration, and melt front history. The heat flow dynamics, as determined by monochromatic (electron energy ranging between 5 and 25 keV) and ultrashort (15 ns fwhm) pulses, is contrasted with the ruby laser induced one. Accessible absorbed energy intervals for sample surface melting are given as a function of electron energy; heating of the sample interior at values higher than those attained at the surface is shown to occur only at higher electron energies, for a given pulse duration. The general dependence of the present results on the pulse duration and the effects produced by polychromatic pulses are also discussed. (author)

  19. Spin observables in the three-body break-up process near the quasi-free limit in deuteron–deuteron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Ramazani-Moghaddam-Arani, A., E-mail: ramazani@kvi.nl [Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); KVI, University of Groningen, Groningen (Netherlands); Mahjour-Shafiei, M. [Department of Physics, University of Tehran, Tehran 1439955961 (Iran, Islamic Republic of); KVI, University of Groningen, Groningen (Netherlands); Amir-Ahmadi, H.R. [KVI, University of Groningen, Groningen (Netherlands); Bacher, A.D.; Bailey, C.D. [Center for Exploration of Energy and Matter, Indiana University, Bloomington, IN (United States); Biegun, A. [KVI, University of Groningen, Groningen (Netherlands); Eslami-Kalantari, M. [KVI, University of Groningen, Groningen (Netherlands); Department of Physics, Faculty of Science, Yazd University, Yazd (Iran, Islamic Republic of); Gašparić, I. [Rudjer Bošković Institute, Zagreb (Croatia); Joulaeizadeh, L.; Kalantar-Nayestanaki, N. [KVI, University of Groningen, Groningen (Netherlands); Kistryn, St. [Institute of Physics, Jagellonian University, Krakow (Poland); Kozela, A. [University of Winnipeg, Winnipeg (Canada); Mardanpour, H.; Messchendorp, J.G. [KVI, University of Groningen, Groningen (Netherlands); Micherdzinska, A.M. [Institute of Nuclear Physics PAN, Krakow (Poland); Moeini, H.; Shende, S.V. [KVI, University of Groningen, Groningen (Netherlands); Stephan, E. [Institute of Physics, University of Silesia, Katowice (Poland); Stephenson, E.J. [Center for Exploration of Energy and Matter, Indiana University, Bloomington, IN (United States); Sworst, R. [Institute of Physics, Jagellonian University, Krakow (Poland)

    2013-10-01

    We have studied spin observables in the three-body break-up reaction in deuteron–deuteron scattering in the phase-space regime that corresponds to the quasi-free deuteron–proton scattering process with the neutron as spectator. The data are compared to measurements of the elastic deuteron–proton scattering process and state-of-the-art Faddeev calculations. The results for iT{sub 11} and T{sub 22} for the quasi-free scattering data agree very well with previously published elastic-scattering data. A significant discrepancy is found for T{sub 20}, which could point to a break-down of the quasi-free assumption.

  20. Receiver function and magnetotelluric analysis to understand the first stage of a continental lithospheric break-up : case of the North Tanzanian Rift

    Science.gov (United States)

    Plasman, M.; Tiberi, C.; Tarits, P.; Hautot, S.; Gautier, S.; Ebinger, C. J.; Mulibo, G. D.; Khalfan, M.

    2015-12-01

    First stage of continental break-up, though intensively studied, is yet poorly understood. This is partly because actual rifting areas are either too mature (more than 10 My) or not easily accessible (thick sediment cover or under water). The North Tanzania part of the East African Rift is the place of a lithosphere's early break-up (less than 5My) in response to a combination of regional pulling forces and mantle upwelling. Deformation there results from complex interactions between magmatic intrusions, faulting, asthenospheric dynamics and far field stresses. CoLiBrEA (ANR) and CRAFTI (NSF) are two multidisciplinary projects which collaboratively focus on this area to understand the interactions between faults and magma, the role of inherited structures and rheological heterogeneities of the lithosphere. For that purpose, we deployed 38 broadband seismic stations in the Natron and Ngorongoro areas from January 2013 to December 2014 and carried out a 120 km East-West magnetotelluric (MT) profile to image the crustal and mantle structures. The 3D resistivity model, obtained from the inversion of the MT data along the profile, shows an highly heterogeneous crust with three-dimensional structures over a more homogeneous upper mantle. The first inversion result from the receiver function (RF) by the Zhu and Kanamori's inversion method show a thick crust (~35 km) with important variations (maximum 15km) especially in the Ngorongoro area, and an average Vp/Vs ratio of 1.75. We then completed this study by combining the MT data and the RF at the 11 sites of the EW profile. For each site, we built a 1D velocity model (Vs and VpVs) obtained by combining the Sambridge forward solution with a non linear descent research algorithm and constrained by the resistivity structure. The inversion shows an heterogeneous crust obviously dominated by the Moho interface at different depths, with low velocity layers mainly corresponding to low resistivity features.

  1. Imaging femtosecond laser-induced electronic excitation in glass

    International Nuclear Information System (INIS)

    Mao Xianglei; Mao, Samuel S.; Russo, Richard E.

    2003-01-01

    While substantial progress has been achieved in understanding laser ablation on the nanosecond and picosecond time scales, it remains a considerable challenge to elucidate the underlying mechanisms during femtosecond laser material interactions. We present experimental observations of electronic excitation inside a wide band gap glass during single femtosecond laser pulse (100 fs, 800 nm) irradiation. Using a femtosecond time-resolved imaging technique, we measured the evolution of a laser-induced electronic plasma inside the glass and calculated the electron number density to be on the order of 10 19 cm -3

  2. Emittance growth induced by electron cloud in proton storage rings

    CERN Document Server

    Benedetto, Elena; Coppa, G

    2006-01-01

    In proton and positron storage rings with many closely spaced bunches, a large number of electrons can accumulate in the beam pipe due to various mechanisms (photoemission, residual gas ionization, beam-induced multipacting). The so-formed electron cloud interacts with the positively charged bunches, giving rise to instabilities, emittance growth and losses. This phenomenon has been observed in several existing machines such as the CERN Super Proton Synchrotron (SPS), whose operation has been constrained by the electron-cloud problem, and it is a concern for the Large Hadron Collider (LHC), under construction at CERN. The interaction between the beam and the electron cloud has features which cannot be fully taken into account by the conventional and known theories from accelerators and plasma physics. Computer simulations are indispensable for a proper prediction and understanding of the instability dynamics. The main feature which renders the beam-cloud interactions so peculiar is that the the electron cloud...

  3. Electron irradiation-induced destruction of carbon nanotubes in electron microscopes

    International Nuclear Information System (INIS)

    Molhave, Kristian; Gudnason, Sven Bjarke; Pedersen, Anders Tegtmeier; Clausen, Casper Hyttel; Horsewell, Andy; Boggild, Peter

    2007-01-01

    Observations of carbon nanotubes under exposure to electron beam irradiation in standard transmission electron microscope (TEM) and scanning electron microscope (SEM) systems show that such treatment in some cases can cause severe damage of the nanotube structure, even at electron energies far below the approximate 100 keV threshold for knock-on damage displacing carbon atoms in the graphene structure. We find that the damage we observe in one TEM can be avoided by use of a cold finger. This and the morphology of the damage imply that water vapour, which is present as a background gas in many vacuum chambers, can damage the nanotube structure through electron beam-induced chemical reactions. Though, the dependence on the background gas makes these observations specific for the presently used systems, the results demonstrate the importance of careful assessment of the level of subtle structural damage that the individual electron microscope system can do to nanostructures during standard use

  4. Electron-stimulated purification of platinum nanostructures grown via focused electron beam induced deposition

    Directory of Open Access Journals (Sweden)

    Brett B. Lewis

    2015-04-01

    Full Text Available Platinum–carbon nanostructures deposited via electron beam induced deposition from MeCpPt(IVMe3 are purified during a post-deposition electron exposure treatment in a localized oxygen ambient at room temperature. Time-dependent studies demonstrate that the process occurs from the top–down. Electron beam energy and current studies demonstrate that the process is controlled by a confluence of the electron energy loss and oxygen concentration. Furthermore, the experimental results are modeled as a 2nd order reaction which is dependent on both the electron energy loss density and the oxygen concentration. In addition to purification, the post-deposition electron stimulated oxygen purification process enhances the resolution of the EBID process due to the isotropic carbon removal from the as-deposited materials which produces high-fidelity shape retention.

  5. [Defence mechanisms and coping strategies in men and women: a comparative and structural study based on the artistic production of people suffering from a break-up of their life project].

    Science.gov (United States)

    Schiltz, L; Ciccarello, A; Ricci-Boyer, L; Schiltz, J

    2013-01-01

    A comparative study of men and women suffering from a break-up of their life project allowed us examining the typically female and male manners to cope with trauma, anxiety, guilt, depression and internal destructivity. In a first stage, an exploratory study was focussed on 206 subjects, belonging to several clinical subgroups: people living in great precarity and long-term unemployed people, asylum seekers and refugees, drug addicts, prisoners and people coming out of prison. Secondly, arts therapeutic sessions were proposed with the aim of helping the participants finding an outlet to their situation. The artistic production (drawings and stories induced by music) was analysed with the help of original rating scales, constructed in a phenomenological and structural perspective. We will present a synthesis of our qualitative observations, as well as some results of typological and structural studies, computed with the help of non parametric statistical procedures on the data of N = 93 participants. The results allow us pointing to gender differences and defining typically male and female coping styles. Differential indications for psychotherapy can be extracted from these analyses.

  6. ERRATUM Electron field emission from sp -induced insulating to ...

    Indian Academy of Sciences (India)

    Administrator

    Electron field emission from sp. 2. -induced insulating to metallic behaviour of amorphous carbon (a-C) films. Pitamber Mahanandia, P N Viswakarma, Prasad Vishnu Bhotla, S V Subramanyam and Karuna Kar Nanda. 2010 Bull. Mater. Sci. 33 pp 215–220. The MS received date should be read as “MS received 20 October ...

  7. Electron field emission from sp 2-induced insulating to metallic ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 33; Issue 3. Electron field emission from 2-induced insulating to metallic behaviour of amorphous carbon (-C) films. Pitamber Mahanandia P N Viswakarma Prasad Vishnu Bhotla S V Subramanyam Karuna Kar Nanda. Thin Films and Nanomatter Volume 33 Issue 3 ...

  8. Ultrafast Hot Electron Induced Phase Transitions in Vanadium Dioxide

    Directory of Open Access Journals (Sweden)

    Haglund R. F.

    2013-03-01

    Full Text Available The Au/Cr/VO2/Si system was investigated in pump–probe experiments. Hot-electrons generated in the Au were found to penetrate into the underlying VO2 and couple with its lattice inducing a semiconductor-to-metal phase transition in ~2 picoseconds.

  9. The role of electron-stimulated desorption in focused electron beam induced deposition

    DEFF Research Database (Denmark)

    van Dorp, Willem F.; Hansen, Thomas Willum; Wagner, Jakob Birkedal

    2013-01-01

    We present the results of our study about the deposition rate of focused electron beam induced processing (FEBIP) as a function of the substrate temperature with the substrate being an electron-transparent amorphous carbon membrane. When W(CO)6 is used as a precursor it is observed that the growth...... experiments compared to literature values is consistent with earlier findings by other authors. The discrepancy is attributed to electron-stimulated desorption, which is known to occur during electron irradiation. The data suggest that, of the W(CO)6 molecules that are affected by the electron irradiation......, the majority desorbs from the surface rather than dissociates to contribute to the deposit. It is important to take this into account during FEBIP experiments, for instance when determining fundamental process parameters such as the activation energy for desorption....

  10. Electron beam induced etching of carbon nanotubes enhanced by secondary electrons in oxygen

    Science.gov (United States)

    Yoshida, Hideto; Tomita, Yuto; Soma, Kentaro; Takeda, Seiji

    2017-05-01

    Multi-walled carbon nanotubes (CNTs) are subjected to electron-beam-induced etching (EBIE) in oxygen. The EBIE process is observed in situ by environmental transmission electron microscopy. The partial pressure of oxygen (10 and 100 Pa), energy of the primary electrons (80 and 200 keV), and environment of the CNTs (suspended or supported on a silicon nitride membrane) are investigated as factors affecting the etching rate. The EBIE rate of CNTs was markedly promoted by the effects of secondary electrons that were emitted from a silicon nitride membrane under irradiation by primary electrons. Membrane supported CNTs can be cut by EBIE with a spatial accuracy better than 3 nm, and a nanogap of 2 nm can be successfully achieved between the ends of two suspended CNTs.

  11. Experimental characterization of the spreading and break-up of liquid flat-fan sheets discharging in a low-density atmosphere and application to BrLi solutions

    Energy Technology Data Exchange (ETDEWEB)

    Palacios, E. [Universidad Politecnica de Madrid (Spain). Departamento de Mecanica Industrial; Nogueira, J.; Rodriguez, P.A.; Lecuona, A. [Universidad Carlos III de Madrid (Spain). Departamento de Ingenieria Termica y de Fluidos

    2009-02-15

    This work presents and characterizes the existence of two different regimes in the spreading and break-up of liquid flat-fan sheets when discharging in low-density atmospheres. The motivation of the study is the improvement on the absorption phenomena of lithium bromide aqueous solution when discharging in a 600-1,500 Pa water vapor environment. This corresponds to the absorber conditions in current absorption closed-cycle cooling machines. Despite this, the dimensionless characterization obtained has universal validity. The conditions that define the change in the break-up regime, the dimensionless sheet break-up length and the break-up time are given as a function of the parameters involved. Digital particle tracking velocimetry (PTV) has been applied to measure the velocity field and additional visualization techniques have been used to further characterize the break-up process. The experiments verify the existence of critical gas-to-liquid density and viscosity ratios below which gas to liquid interaction becomes negligible. The article also offers expressions that define their values as a function of the other dimensionless parameters. (orig.)

  12. Relativistic electron dropout echoes induced by interplanetary shocks

    Science.gov (United States)

    Schiller, Q.; Kanekal, S. G.; Boyd, A. J.; Baker, D. N.; Blake, J. B.; Spence, H. E.

    2017-12-01

    Interplanetary shocks that impact Earth's magnetosphere can produce immediate and dramatic responses in the trapped relativistic electron population. One well-studied response is a prompt injection capable of transporting relativistic electrons deep into the magnetosphere and accelerating them to multi-MeV energies. The converse effect, electron dropout echoes, are observations of a sudden dropout of electron fluxes observed after the interplanetary shock arrival. Like the injection echo signatures, dropout echoes can also show clear energy dispersion signals. They are of particular interest because they have only recently been observed and their causal mechanism is not well understood. In the analysis presented here, we show observations of electron drift echo signatures from the Relativistic Electron-Proton Telescope (REPT) and Magnetic Electron and Ion Sensors (MagEIS) onboard NASA's Van Allen Probes mission, which show simultaneous prompt enhancements and dropouts within minutes of the associated with shock impact. We show that the observations associated with both enhancements and dropouts are explained by the inward motion caused by the electric field impulse induced by the interplanetary shock, and either energization to cause the enhancement, or lack of a seed population to cause the dropout.

  13. North west cape-induced electron precipitation and theoretical simulation

    Science.gov (United States)

    Zhang, Zhen-xia; Li, Xin-qiao; Wang, Chen-Yu; Chen, Lun-Jin

    2016-11-01

    Enhancement of the electron fluxes in the inner radiation belt, which is induced by the powerful North West Cape (NWC) very-low-frequency (VLF) transmitter, have been observed and analyzed by several research groups. However, all of the previous publications have focused on NWC-induced > 100-keV electrons only, based on observations from the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and the Geostationary Operational Environmental Satellite (GOES) satellites. Here, we present flux enhancements with 30-100-keV electrons related to NWC transmitter for the first time, which were observed by the GOES satellite at night. Similar to the 100-300-keV precipitated-electron behavior, the low energy 30-100-keV electron precipitation is primarily located east of the transmitter. However, the latter does not drift eastward to the same extent as the former, possibly because of the lower electron velocity. The 30-100-keV electrons are distributed in the L = 1.8-2.1 L-shell range, in contrast to the 100-300-keV electrons which are at L = 1.67-1.9. This is consistent with the perspective that the energy of the VLF-wave-induced electron flux enhancement decreases with higher L-shell values. We expand upon the rationality of the simultaneous enhancement of the 30-100- and 100-300-keV electron fluxes through comparison with the cyclotron resonance theory for the quasi-linear wave-particle interaction. In addition, we interpret the asymmetry characteristics of NWC electric power distribution in north and south hemisphere by ray tracing model. Finally, we present considerable discussion and show that good agreement exists between the observation of satellites and theory. Supported by the China Seismo-Electromagnetic Satellite Mission Ground-Based Verification Project of the Administration of Science, Technology, and Industry for National Defense and Asia-Pacific Space Cooperation Organization Project (APSCO-SP/PM-EARTHQUAKE).

  14. 5th International Workshop on Desorption Induced by Electronic Transitions

    CERN Document Server

    Jennison, Dwight R; Stechel, Ellen B; DIET V; Desorption induced by electronic transitions

    1993-01-01

    This volume in the Springer Series on Surface Sciences presents a recent account of advances in the ever-broadening field of electron-and photon-stimulated sur­ face processes. As in previous volumes, these advances are presented as the proceedings of the International Workshop on Desorption Induced by Electronic Transitions; the fifth workshop (DIET V) was held in Taos, New Mexico, April 1-4, 1992. It will be abundantly clear to the reader that "DIET" is not restricted to desorption, but has for several years included photochemistry, non-thermal surface modification, exciton self-trapping, and many other phenomena that are induced by electron or photon bombardment. However, most stimulated surface processes do share a common physics: initial electronic excitation, localization of the excitation, and conversion of electronic energy into nuclear kinetic energy. It is the rich variation of this theme which makes the field so interesting and fruitful. We have divided the book into eleven parts in orde...

  15. Bias-induced insulator-metal transition in organic electronics

    Science.gov (United States)

    Wei, J. H.; Xie, S. J.; Mei, L. M.; Yan, YiJing

    2007-07-01

    The authors investigate the bias-induced insulator-metal transition in organic electronics devices on the basis of the Su-Schrieffer-Heeger model [W. P. Su et al., Phys. Rev. B 22, 2099 (1980)] combined with the nonequilibrium Green's function formalism. The insulator-metal transition is explained with the energy level crossover that eliminates the Peierls phase [R. Peierls, Quantum Theory of Solids (Oxford University Press, Oxford, 1955)] and delocalizes the electron states near the threshold voltage. This may account for the experimental observations on the devices that exhibit intrinsic bistable conductance switching with large on-off ratio.

  16. Northwestcape-induced Electron Precipitation and Theoretica Simulation

    Science.gov (United States)

    Zhang, Z.; Li, X.; Wang, C.; Chen, L.

    2017-12-01

    Enhancement of the electron fluxes in the inner radiation belt, which is induced by the powerful North West Cape (NWC) very-low-frequency (VLF) transmitter, have been observed and analyzed by several research groups. However, all of the previous publications have focused on NWC-induced > 100-keV electrons only, based on observations from the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and the Geostationary Operational Environmental Satellite (GOES) satellites. Here, we present flux enhancements with 30-100-keV electrons related to NWC transmitter for the first time, which were observed by the GOES satellite at night. Similar to the 100- 300-keV precipitated-electron behavior, the low energy 30-100-keV electron precipitation is primarily located east of the transmitter. However, the latter does not drift eastward to the same extent as the former, possibly because of the lower electron velocity. The 30-100-keV electrons are distributed in the L = 1.8-2.1 L-shell range, in contrast to the 100-300-keVelectronswhichareatL=1.67-1.9. ThisisconsistentwiththeperspectivethattheenergyoftheVLF-waveinducedelectronfluxenhancementdecreaseswithhigherL-shellvalues. Weexpandupontherationalityofthesimultaneous enhancementofthe30-100-and100-300-keVelectronfluxesthroughcomparisonwiththecyclotronresonancetheoryfor the quasi-linear wave-particle interaction. In addition, we interpret the asymmetry characteristics of NWC electric power distribution in northand south hemisphere by ray tracing model. Finally, we present considerable discussionand showthat good agreement exists between the observation of satellites and theory.

  17. Erosion and break-up of light-gas layers by a horizontal jet in a multi-vessel, large-scale containment test system

    Energy Technology Data Exchange (ETDEWEB)

    Zboray, Robert, E-mail: robert.zboray@psi.ch; Mignot, Guillaume; Kapulla, Ralf; Paladino, Domenico

    2015-09-15

    The distribution and eventual stratification of hydrogen released during a hypothetical severe accident and the stability of the stratification formed in the early phase of the transient is of particular safety concern in Light Water Reactors (LWRs). The large-scale containment test facility PANDA (PSI, Switzerland) has been used to perform a series of four tests examining the erosion and break-up of stratified light-gas layers in the frame of the OECD SETH-2 project. The ultimate goal of the test program is to set-up an experimental data base of high-quality and high-density data that can challenge and validate 3D containment codes like e.g. GOTHIC, GASFLOW or MARS and validate the applicability of CFD codes like FLUENT or CFX for LWR containment problems. The test series discussed here focuses on the erosion of a stratified, helium-rich layer by horizontal steam injection at different locations below the layer. An approach with step-wise increasing complexity has been chosen to examine this problem allowing control over the rate of pressure increase and the occurrence of condensation. The step-wise approach enables a thorough understanding of the influence of different phenomena like position of steam injection, diffusion, pressurization and condensation on the behavior and erosion of the stratified layer.

  18. Comparison of non-invasive tear break-up time and tear meniscus height in healthy eyes and keratoconus using Oculus Keratograph 5M

    Directory of Open Access Journals (Sweden)

    Masoud Safarzadeh

    2017-09-01

    Full Text Available AIM: To compare the non-invasive tear break-up time(NITBUTand tear meniscus height(TMHmeasurements in keratoconus patients and normal subjects, and to determine the relationship between these measurements with keratoconus disease by the Oculus Keratograph 5M(K5M. METHODS:Fifty keratoconus patients(100 eyesand 50 healthy subjects(100 eyesparticipated in the study. The age range in keratoconus group was 15-60(mean ± standard deviation=28.33±8.60y, and in control group was 18-60(26.25±1.11y. The measurements of NITBUT and TMH were performed using the K5M. RESULTS: The mean value of NITBUT between the keratoconus group and the control group showed no statistically significant different(P=0.58. Also, the mean of TMH between two groups was not significantly different(P=0.69. The results of correlation coefficient between the variables of the study demonstrated that there was no significant relationship between the NITBUT and TMH measurements with the two groups(keratoconus group: r= 0.053, P=0.721; control group; r=-0.0501, P=0.7098. CONCLUSION: Our study shows that the presence of keratoconus has no clinically significant impact on the quality and quantity of tear film.

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

    KAUST Repository

    Tahini, H. A.

    2012-04-17

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

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

    Science.gov (United States)

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

    2012-05-16

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

  1. How effective are slurry storage, cover or catch crops, woodland creation, controlled trafficking or break-up of compacted layers, and buffer strips as on-farm mitigation measures for delivering an improved water environment?

    Directory of Open Access Journals (Sweden)

    Randall Nicola P

    2012-10-01

    Full Text Available Abstract Background Agriculture has intensified over the last 50 years resulting in increased usage of fertilizers and agrochemicals, changes in cropping practices, land drainage and increased stocking rates. In Europe, this has resulted in declines in the quality of soils and waters due to increased run off and water pollution. Fifty percent of nitrates in European rivers are derived from agricultural sources in the UK this value is as high as 70%, where agriculture also contributes to approximately 28% of phosphates and 76% of sediments recorded in rivers. Catchments dominated by agricultural land use have increased levels of pesticides and bacterial pathogens. European member states have a policy commitment to tackle water pollution through the Water Framework Directive. An analysis of the effectiveness of water pollution mitigation measures should enable decision makers and delivery agencies to better facilitate catchment planning. The aim of this systematic review is to assess the effectiveness of slurry storage, cover/catch crops, woodland creation, controlled trafficking/break-up of compacted layers and buffer strips, as on farm mitigation measures, for delivering an improved water environment. Methods The systematic review will consist of a searchable systematic map database for all the named interventions. Where possible, quantitative analysis will be used to assess the effectiveness of interventions. Electronic databases, the internet, and organisational websites will be searched, and stakeholders will be contacted for studies that investigate the impact of the on-farm mitigation measures on water quality. All studies found will be assessed for suitability for inclusion in the next stage. Inclusion criteria will be based on subject, intervention, comparator and outcome. The details of included studies will be incorporated into the systematic map database, and studies scored for effectiveness of intervention and study design. Where

  2. Probing Spin Accumulation induced Magnetocapacitance in a Single Electron Transistor.

    Science.gov (United States)

    Lee, Teik-Hui; Chen, Chii-Dong

    2015-09-08

    The interplay between spin and charge in solids is currently among the most discussed topics in condensed matter physics. Such interplay gives rise to magneto-electric coupling, which in the case of solids was named magneto-electric effect, as predicted by Curie on the basis of symmetry considerations. This effect enables the manipulation of magnetization using electrical field or, conversely, the manipulation of electrical polarization by magnetic field. The latter is known as the magnetocapacitance effect. Here, we show that non-equilibrium spin accumulation can induce tunnel magnetocapacitance through the formation of a tiny charge dipole. This dipole can effectively give rise to an additional serial capacitance, which represents an extra charging energy that the tunneling electrons would encounter. In the sequential tunneling regime, this extra energy can be understood as the energy required for a single spin to flip. A ferromagnetic single-electron-transistor with tunable magnetic configuration is utilized to demonstrate the proposed mechanism. It is found that the extra threshold energy is experienced only by electrons entering the islands, bringing about asymmetry in the measured Coulomb diamond. This asymmetry is an unambiguous evidence of spin accumulation induced tunnel magnetocapacitance, and the measured magnetocapacitance value is as high as 40%.

  3. Steric-electronic effects in malarial peptides inducing sterile immunity

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Vranich, Armando [Fundacion Instituto de Inmunologia de Colombia (FIDIC), Bogota (Colombia); Patarroyo, Manuel E., E-mail: mepatarr@mail.com [Fundacion Instituto de Inmunologia de Colombia (FIDIC), Bogota (Colombia); Universidad Nacional de Colombia, Bogota (Colombia)

    2012-07-13

    Highlights: Black-Right-Pointing-Pointer Is it evident that the residues position are relevant regarding of {phi} angular value. Black-Right-Pointing-Pointer The geometry considered for detailing the alterations undergone by HABPs. Black-Right-Pointing-Pointer The inter planar interactions ruled by clashes between the atoms making them up. -- Abstract: Conserved Plasmodium falciparum high activity binding peptides' (HABPs) most relevant proteins involved in malaria parasite invasion are immunologically silent; critical binding residues must therefore be specifically replaced to render them highly immunogenic and protection-inducing. Such changes have a tremendous impact on these peptides' steric-electronic effects, such as modifications to peptide length peptide bonds and electronic orbitals' disposition, to allow a better fit into immune system MHCII molecules and better interaction with the TCR which might account for the final immunological outcome.

  4. Effects of Systane® Balance on noninvasive tear film break-up time in patients with lipid-deficient dry eye

    Directory of Open Access Journals (Sweden)

    Aguilar AJ

    2014-11-01

    Full Text Available Alejandro J Aguilar, Maria I Marquez, Paula A Albera, Jorge L Tredicce, Alejandro Berra Universidad de Buenos Aires, Buenos Aires, Argentina Purpose: To evaluate the ability of Systane® Balance (SYSB administered four times per day for 4 weeks to increase noninvasive tear film break-up time (NITFBUT over baseline compared with a saline (SAL control in patients with lipid-deficient dry eye (DE.Patients and methods: Patients aged ≥18 years with DE and evidence of meibomian gland dysfunction (ie, abnormal gland expression and missing meibomian glands were included in this randomized, parallel-group, controlled, investigator-masked comparison study. Patients were randomized to SYSB or SAL four times daily for 4 weeks. The primary efficacy variable was mean change in NITFBUT from baseline at week 4. Ocular surface staining, goblet cell density, and meibomian gland expression were also assessed. Safety assessments included adverse events (AEs, best-corrected visual acuity, and ocular signs.Results: A total of 49 patients received study treatments (SYSB, n=25; SAL, n=24. Most patients were women (67.4% and Caucasian (63.3%; mean ± standard deviation (SD age was 44±19 years. DE characteristics at baseline were similar between groups. After 4 weeks of treatment, the mean ± SD NITFBUT increase from baseline was significantly greater with SYSB (2.83±0.74 seconds compared with SAL (0.66±0.55 seconds; P<0.001, t-test. Improvements in conjunctival and corneal staining, percentage of patients with increased goblet cell density, and meibomian gland expression were also observed with 4 weeks of SYSB over SAL. No AEs were reported for either treatment group; best-corrected visual acuity and ocular signs remained stable or improved compared with baseline.Conclusion: SYSB restored tear film stability, improved ocular surface healing, and improved meibomian gland functionality after 4 weeks of use in patients with lipid-deficient DE. No AEs were reported

  5. Ocular symptoms and tear film break up time (BUT) among junior high school students in Penang, Malaysia - Associations with fungal DNA in school dust.

    Science.gov (United States)

    Norbäck, Dan; Hashim, Jamal Hisham; Hashim, Zailina; Sooria, Vinoshini; Ismail, Syazwan Aizat; Wieslander, Gunilla

    2017-06-01

    There are few studies on ocular effects of indoor mould exposure in schools, especially in the tropics OBJECTIVE: To study associations between eye symptoms and tear film break up time (BUT) in students and demographic data and fungal DNA in schools. A school environment study was performed among randomly selected students in eight randomly selected secondary schools in Penang, Malaysia. Information on eye symptoms and demographic data was collected by a standardised questionnaire. BUT was measured by two methods, self-reported BUT (SBUT) and by the non-invasive Tearscope (NIBUT). Dust was collected by vacuuming in 32 classrooms and analysed for five fungal DNA sequences. Geometric mean (GM) for total fungal DNA was 7.31*10 4 target copies per gram dust and for Aspergillus/Penicillium DNA 3.34*10 4 target copies per gram dust. Linear mixed models and 3-level multiple logistic regression were applied adjusting for demographic factors. A total of 368 students (58%) participated and 17.4% reported weekly eye symptoms the last 3 months. The median SBUT and TBUT were 15 and 12s, respectively. Students wearing glasses (OR 2.41, p=0.01) and with a history of atopy (OR=2.67; p=0.008) had more eye symptoms. Girls had less eye symptoms than boys (OR=0.34; p=0.006) Indoor carbon dioxide in the classrooms was low (range 380-720ppm), temperature was 25-30°C and relative air humidity 70-88%. Total fungal DNA in vacuumed dust was associated with shorter SBUT (4s shorter per 10 5 target copies per gram dust; p=0.04) and NIBUT (4s shorter per 10 5 target copies per gram dust; p<0.001). Aspergillus/Penicillium DNA was associated with shorter NIBUT (5s shorter per 10 5 target copies per gram dust; p=0.01). Fungal contamination in schools in a tropical country can be a risk factor for impaired tear film stability among students. Copyright © 2017 Elsevier GmbH. All rights reserved.

  6. Neutron induced electron radiography; Radiografia com eletrons induzida por neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Marcos Leandro Garcia

    2008-07-01

    In the present paper a new radiography technique, the 'Neutron Induced Electron Radiography' - NIER, to inspect low thickness samples on the order of micra, has been developed. This technique makes use of low energy electrons as penetrating radiation generated from metallic gadolinium screens when irradiated by thermal neutrons. The conditions to obtain the best image for the conventional X-ray film Kodak-AA were determined by using a digital system to quantify the darkening level of the film. The irradiations have been performed at a radiography equipment installed at the beam-hole no. 8 of the 5 MW IEA-R1 nuclear research reactor of IPEN-CNEN/SP. The irradiation time to obtain the best radiography was 100 seconds and for such condition the technique was able to discern 1 {mu}m in 24 {mu}m of aluminum at a resolution of 32 {mu}m. By visual comparison the images obtained by the NIER shown a higher quality when compared with the ones from other usual techniques the make use of electrons a penetrating radiation and films for image registration. Furthermore the use of the digital system has provided a smaller time for data acquisition and data analysis as well as an improvement in the image visualization. (author)

  7. 2nd International Workshop on Desorption Induced by Electronic Transitions

    CERN Document Server

    Menzel, Dietrich

    1985-01-01

    The second workshop on Desorption Induced by Electronic Transitions (DIET II) took place October 15-17, 1984, in SchloB Elmau, Bavaria. DIET II, fol­ lowing the great success of DIET I (edited by N. H. Tolk, M. M. Traum, J. C. Tully, T. E. Madey and published in Springer Ser. Chem. Phys. , Vol. 24), again brought together over 60 workers in this exciting field. The "hard co­ re of experts" was essentially the same as in DIET I but the general overlap of participants between the two meetings was small. While DIET I had the function of an exposition of the status of the field DIET II focussed more on new developments. The main emphasis was again on the microscopic under­ standing of DIET but a number of side aspects and the application of DIET ideas to other fields such as sputtering, laser-induced desorption, fractu­ re, erosion, etc. were considered, too. New mechanisms and new refined expe­ rimental techniques were proposed and discussed at the meeting critically but with great enthusiasm. In addition t...

  8. 3rd International Workshop on Desorption Induced by Electronic Transitions

    CERN Document Server

    Knotek, Michael

    1988-01-01

    These proceedings are the result of the third international workshop on Desorption Induced by Electronic Transitions, DIET III, which took place on Shelter Island, NY, May. 20-22, 1987. The work contained in this volume is an excellent summary of the current status of the field and should be a valuable reference text for both "seasoned" researchers and newcomers in the field of DIET. Based on the success of the meeting it seems clear that interest and enthusiasm in the field is strong. It is also apparent, from the many lively discussions during the meeting, that many unanswered questions (and controversies) remain to be solved. It was particularly pleasing to see many new participants from new and rapidly advancing fields, ranging from gas phase dynamics to semiconductor processing. The resulting cross-fertilization from these separate but related fields is playing an important role in helping us understand desorption processes at solid surfaces. In general, the topics covered during the course of the worksh...

  9. Dynamical photo-induced electronic properties of molecular junctions

    Science.gov (United States)

    Beltako, K.; Michelini, F.; Cavassilas, N.; Raymond, L.

    2018-03-01

    Nanoscale molecular-electronic devices and machines are emerging as promising functional elements, naturally flexible and efficient, for next-generation technologies. A deeper understanding of carrier dynamics in molecular junctions is expected to benefit many fields of nanoelectronics and power devices. We determine time-resolved charge current flowing at the donor-acceptor interface in molecular junctions connected to metallic electrodes by means of quantum transport simulations. The current is induced by the interaction of the donor with a Gaussian-shape femtosecond laser pulse. Effects of the molecular internal coupling, metal-molecule tunneling, and light-donor coupling on photocurrent are discussed. We then define the time-resolved local density of states which is proposed as an efficient tool to describe the absorbing molecule in contact with metallic electrodes. Non-equilibrium reorganization of hybridized molecular orbitals through the light-donor interaction gives rise to two phenomena: the dynamical Rabi shift and the appearance of Floquet-like states. Such insights into the dynamical photoelectronic structure of molecules are of strong interest for ultrafast spectroscopy and open avenues toward the possibility of analyzing and controlling the internal properties of quantum nanodevices with pump-push photocurrent spectroscopy.

  10. Laser-induced forward transfer for printed electronics applications

    Science.gov (United States)

    Fernández-Pradas, J. M.; Sopeña, P.; González-Torres, S.; Arrese, J.; Cirera, A.; Serra, P.

    2018-02-01

    Laser-induced forward transfer (LIFT) is a printing technique based on the action of a laser pulse that is focused on a thin film of a precursor ink for getting the transfer of a droplet onto a receiver substrate. The experiments presented in this article aim to demonstrate the ability of LIFT to produce electronic circuits on paper, a substrate that is flexible, cheap and recyclable. Tests were conducted to study the printing of conductive tracks with an Ag ink. The printing of a suspension of carbon nanofibers was also studied to demonstrate the ability of LIFT for printing inks with particles with some microns in size that provoke inkjet nozzles to clog. As a proof-of-concept of the LIFT possibilities, both inks were used to print entirely by LIFT a functional humidity sensor on a piece of paper. All the LIFT experiments were performed with a Nd:YAG laser that delivers pulses of a few hundreds of ns in an attempt to approach the technique to laser systems that are already introduced in many production lines for marking and labeling.

  11. An optimized nanoparticle separator enabled by electron beam induced deposition

    International Nuclear Information System (INIS)

    Fowlkes, J D; Rack, P D; Doktycz, M J

    2010-01-01

    Size-based separations technologies will inevitably benefit from advances in nanotechnology. Direct-write nanofabrication provides a useful mechanism for depositing/etching nanoscale elements in environments otherwise inaccessible to conventional nanofabrication techniques. Here, electron beam induced deposition was used to deposit an array of nanoscale features in a 3D environment with minimal material proximity effects outside the beam-interaction region. Specifically, the membrane component of a nanoparticle separator was fabricated by depositing a linear array of sharply tipped nanopillars, with a singular pitch, designed for sub-50 nm nanoparticle permeability. The nanopillar membrane was used in a dual capacity to control the flow of nanoparticles in the transaxial direction of the array while facilitating the sealing of the cellular-sized compartment in the paraxial direction. An optimized growth recipe resulted which (1) maximized the growth efficiency of the membrane (which minimizes proximity effects) and (2) preserved the fidelity of the spacing between nanopillars (which maximizes the size-based gating quality of the membrane) while (3) maintaining sharp nanopillar apexes for impaling an optically transparent polymeric lid critical for device sealing.

  12. Electron-electron interactions in graphene field-induced quantum dots in a high magnetic field

    DEFF Research Database (Denmark)

    Orlof, A.; Shylau, Artsem; Zozoulenko, I. V.

    2015-01-01

    We study the effect of electron-electron interaction in graphene quantum dots defined by an external electrostatic potential and a high magnetic field. To account for the electron-electron interaction, we use the Thomas-Fermi approximation and find that electron screening causes the formation...... of compressible strips in the potential profile and the electron density. We numerically solve the Dirac equations describing the electron dynamics in quantum dots, and we demonstrate that compressible strips lead to the appearance of plateaus in the electron energies as a function of the magnetic field. Finally...

  13. Electron spin resonance study of interface states induced by electron injection in metal-oxide-semiconductor devices

    Science.gov (United States)

    Mikawa, R. E.; Lenahan, P. M.

    1986-03-01

    We find that electrons emitted from silicon into the oxide of metal-oxide-silicon devices generate amphoteric trivalent silicon (Pb center) defects at the Si/SiO2 interface. The Pb centers are generated in numbers approximately equal to that of the electron injection induced interface states. The effects of electron injection are similar to those of ionizing radiation to the extent that in both cases Pb centers are generated at the Si/SiO2 interface. However, the effects are not identical; ionizing radiation creates another trivalent silicon defect, termed E', in the oxide. We are unable to observe any E' generation in oxides subjected to electron injection. There appears to be a strong correlation between the number of trapped electrons and the electron injection induced Pb center interface states; this observation suggests that the trapping of electrons in the bulk of the oxides is in some way related to the creation of the Pb center interface state defects. We find that dry oxides subjected to a deuterium/nitrogen anneal exhibit less electron trapping than otherwise identical oxides which have been subjected to a hydrogen/nitrogen anneal. This observation is consistent with the idea that a hydrogen bond breaking event may be involved in electron capture.

  14. Kinetic electron emission from Cu induced by impact of slow Cs+ ions

    Czech Academy of Sciences Publication Activity Database

    Lorinčík, Jan; Šroubek, Zdeněk; Kormunda, M.; Matoušek, J.

    2013-01-01

    Roč. 315, 15 November (2013), s. 287-290 ISSN 0168-583X R&D Projects: GA MŠk(CZ) ME10086 Institutional support: RVO:67985882 Keywords : Ion induced electron emission * Kinetic electron emission * Sub-threshold Cs+ Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.186, year: 2013

  15. Kinetic electron emission from metal surfaces induced by impact of slow ions

    Czech Academy of Sciences Publication Activity Database

    Šroubek, Zdeněk; Lorinčík, Jan

    -, č. 625 (2014), s. 7-9 ISSN 0039-6028 R&D Projects: GA MŠk(CZ) ME10086 Institutional support: RVO:67985882 Keywords : Ion induced kinetic electron emission * Electronic excitation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.925, year: 2014

  16. Ultrahigh resolution focused electron beam induced processing: the effect of substrate thickness

    DEFF Research Database (Denmark)

    van Dorp, Willem F; Lazic, Ivan; Beyer, André

    2011-01-01

    It is often suggested that the growth in focused electron beam induced processing (FEBIP) is caused not only by primary electrons, but also (and even predominantly) by secondary electrons (SEs). If that is true, the growth rate for FEBIP can be changed by modifying the SE yield. Results from our ...

  17. The effect of electron range on electron beam induced current collection and a simple method to extract an electron range for any generation function

    International Nuclear Information System (INIS)

    Lahreche, A.; Beggah, Y.; Corkish, R.

    2011-01-01

    The effect of electron range on electron beam induced current (EBIC) is demonstrated and the problem of the choice of the optimal electron ranges to use with simple uniform and point generation function models is resolved by proposing a method to extract an electron range-energy relationship (ERER). The results show that the use of these extracted electron ranges remove the previous disagreement between the EBIC curves computed with simple forms of generation model and those based on a more realistic generation model. The impact of these extracted electron ranges on the extraction of diffusion length, surface recombination velocity and EBIC contrast of defects is discussed. It is also demonstrated that, for the case of uniform generation, the computed EBIC current is independent of the assumed shape of the generation volume. -- Highlights: → Effect of electron ranges on modeling electron beam induced current is shown. → A method to extract an electron range for simple form of generation is proposed. → For uniform generation the EBIC current is independent of the choice of it shape. → Uses of the extracted electron ranges remove some existing literature ambiguity.

  18. Evolutionary loss of light-harvesting proteins Lhcb6 and Lhcb3 in major land plant groups - break-up of current dogma

    Czech Academy of Sciences Publication Activity Database

    Kouřil, R.; Nosek, L.; Bartoš, Jan; Boekema, E. J.; Ilík, P.

    2016-01-01

    Roč. 210, č. 3 (2016), s. 808-814 ISSN 0028-646X R&D Projects: GA ČR GA13-28093S; GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : conifers * electron microscopy * evolution Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 7.330, year: 2016

  19. Deeply concealed half-graben at the SW margin of the East European Craton (SE Poland) — Evidence for Neoproterozoic rifting prior to the break-up of Rodinia

    OpenAIRE

    P. Krzywiec; P. Poprawa; M. Mikołajczak; S. Mazur; M. Malinowski

    2018-01-01

    Baltica was one of continents formed as a result of Rodinia break-up 850–550 Ma. It was separated from Amazonia(?) by the Tornquist Ocean, the opening of which was preceded by Neoproterozoic extension in a network of continental rifts. Some of these rifts were subsequently aborted whereas the Tornquist Rift gave rise to splitting of Rodinia and formation of the Tornquist Ocean. The results of 1-D subsidence analysis at the fossil passive margin of Baltica provided insight in the timing and ki...

  20. Deeply concealed half-graben at the SW margin of the East European Craton (SE Poland — Evidence for Neoproterozoic rifting prior to the break-up of Rodinia

    Directory of Open Access Journals (Sweden)

    P. Krzywiec

    2018-01-01

    Full Text Available Baltica was one of continents formed as a result of Rodinia break-up 850–550 Ma. It was separated from Amazonia(? by the Tornquist Ocean, the opening of which was preceded by Neoproterozoic extension in a network of continental rifts. Some of these rifts were subsequently aborted whereas the Tornquist Rift gave rise to splitting of Rodinia and formation of the Tornquist Ocean. The results of 1-D subsidence analysis at the fossil passive margin of Baltica provided insight in the timing and kinematics of continental rifting that led to break-up of Rodinia. Rifting was associated with Neoproterozoic syn-rift subsidence accompanied by deposition of continental coarse-grained sediments and emplacement of continental basalts. Transition from a syn-rift to post-rift phase in the latest Ediacaran to earliest early Cambrian was concomitant with deposition of continental conglomerates and arkoses, laterally passing into mudstones. An extensional scenario of the break-up of Rodinia along the Tornquist Rift is based on the character of tectonic subsidence curves, evolution of syn-rift and post-rift depocenters in time, as well as geochemistry and geochronology of the syn-rift volcanics. It is additionally reinforced by the high-quality deep seismic reflection data from SE Poland, located above the SW edge of the East European Craton. The seismic data allowed for identification of a deeply buried (11–18 km, well-preserved extensional half-graben, developed in the Palaeoproterozoic crystalline basement and filled with a Neoproterozoic syn-rift volcano-sedimentary succession. The results of depth-to-basement study based on integration of seismic and gravity data show the distribution of local NE–SW elongated Neoproterozoic depocenters within the SW slope of the East European Craton. Furthermore, they document the rapid south-eastwards thickness increase of the Neoproterozoic succession towards the NW–SE oriented craton margin. This provides evidence

  1. In situ transmission electron microscopy analysis of electron beam induced crystallization of amorphous marks in phase-change materials

    International Nuclear Information System (INIS)

    Kaiser, M.; Pieterson, L. van; Verheijen, M.A.

    2004-01-01

    Crystallization of amorphous data marks in crystalline Ga 15 Sb 85 and Ge,In doped SbTe phase-change material was studied in situ in a Transmission Electron Microscope (TEM). Electron irradiation induced crystallization was obtained at room temperature using a 120 kV beam. In general, electron beam (e - beam) induced crystallization started from the amorphous-crystalline interface and was growth dominated for both materials. A dependence of growth velocity on electron beam intensity and crystal direction was observed. A comparison with laser-crystallized amorphous marks was made. For laser-induced crystallization also crystal growth from the amorphous-crystalline interface was seen. However, differences in morphology between the e - -beam and laser-recrystallized data marks of the GaSb phase-change material were observed. The electron beam erased data marks contained crystals with (extremely) large periodicities found in three dimensions. For the Ge,In doped SbTe phase-change material identical morphologies were observed for the e - -beam and laser-recrystallized data marks. Both methods that induce crystallization displayed a rhombohedral Sb structure, the same structure as the laser-crystallized surroundings

  2. Electron emission induced modifications in amorphous tetrahedral diamondlike carbon

    International Nuclear Information System (INIS)

    Mercer, T.W.; DiNardo, N.J.; Rothman, J.B.; Siegal, M.P.; Friedmann, T.A.; Martinez-Miranda, L.J.

    1998-01-01

    The cold-cathode electron emission properties of amorphous tetrahedral diamondlike carbon are promising for flat-panel display and vacuum microelectronics technologies. The onset of electron emission is, typically, preceded by open-quotes conditioningclose quotes where the material is stressed by an applied electric field. To simulate conditioning and assess its effect, we combined the spatially localized field and current of a scanning tunneling microscope tip with high-spatial-resolution characterization. Scanning force microscopy shows that conditioning alters surface morphology and electronic structure. Spatially resolved electron-energy-loss spectroscopy indicates that the predominant bonding configuration changes from predominantly fourfold to threefold coordination. copyright 1998 American Institute of Physics

  3. Parity-violating electric-dipole transitions in helium induced by the electron-electron neutral weak interaction

    Energy Technology Data Exchange (ETDEWEB)

    Esteve, J.G.; Morales, A.; Morales, J.; Nuez-Lagos, R.; Pacheco, A.F.

    1984-04-01

    The parity-violating E1 transitions between the n = 2 levels of atomic helium, induced by the electron-electron neutral weak interaction have been computed by using Coulomb-type wave functions and (up to 84 parameter) Hylleraas wave functions. The parity-violating matrix elements turn out to be of the same order of magnitude as those due to the electron-nucleus weak interaction, thus allowing one to conclude that the relative importance of both effects is to be traced to their corresponding effective coupling constants.

  4. Quantum electron transfer processes induced by thermo-coherent ...

    Indian Academy of Sciences (India)

    WINTEC

    very high temperature the expressions are derived analytically and compared with the case of thermal distri- bution. We have investigated the dependence of temperature on the rate due to displacement, distortion of the harmonic potential energy ... one electron two-centered exchange problem,7–10 many electron direct ...

  5. Electron field emission from sp 2-induced insulating to metallic ...

    Indian Academy of Sciences (India)

    The influence of concentration and size of 2 cluster on the transport properties and electron field emissions of amorphous carbon films have been investigated. The observed insulating to metallic behaviour from reduced activation energy derived from transport measurement and threshold field for electron emission of ...

  6. Communication: Electronic flux induced by crossing the transition state

    Science.gov (United States)

    Jia, Dongming; Manz, Jörn; Yang, Yonggang

    2018-01-01

    We present a new effect of chemical reactions, e.g., isomerizations, that occurs when the reactants pass along the transition state, on the way to products. It is based on the well-known fact that at the transition state, the electronic structure of one isomer changes to the other. We discover that this switch of electronic structure causes a strong electronic flux that is well distinguishable from the usual flux of electrons that travel with the nuclei. As a simple but clear example, the effect is demonstrated here for bond length isomerization of Na2 (21Σu+), with adiabatic crossing the barrier between the inner and outer wells of the double minimum potential that support different "Rydberg" and "ionic" type electronic structures, respectively.

  7. Electron gas induced in SrTiO3

    Science.gov (United States)

    Fu, Han; Reich, K. V.; Shklovskii, B. I.

    2016-03-01

    This mini-review is dedicated to the 85th birthday of Prof. L.V. Keldysh, from whom we have learned so much. In this paper, we study the potential and electron density depth profiles in surface accumulation layers in crystals with a large and nonlinear dielectric response such as SrTiO3 (STO) in the cases of planar, spherical, and cylindrical geometries. The electron gas can be created by applying an induction D 0 to the STO surface. We describe the lattice dielectric response of STO using the Landau-Ginzburg free energy expansion and employ the Thomas-Fermi (TF) approximation for the electron gas. For the planar geometry, we arrive at the electron density profile n( x) ∝ ( x + d)-12/7, where d ∝ D 0 -12/7 . We extend our results to overlapping electron gases in GTO/STO/GTO heterojunctions and electron gases created by spill-out from NSTO (heavily n-type doped STO) layers into STO. Generalization of our approach to a spherical donor cluster creating a big TF atom with electrons in STO brings us to the problem of supercharged nuclei. It is known that for an atom with a nuclear charge Ze where Z > 170, electrons collapse onto the nucleus, resulting in a net charge Zn < Z. Here, instead of relativistic physics, the collapse is caused by the nonlinear dielectric response. Electrons collapse into the charged spherical donor cluster with radius R when its total charge number Z exceeds the critical value Z c ≈ R/ a, where a is the lattice constant. The net charge e Z n grows with Z until Z exceeds Z* ≈ ( R/ a)9/7. After this point, the charge number of the compact core Z n remains ≈ Z*, with the rest Z* electrons forming a sparse TF atom with it. We extend our studies of collapse to the case of long cylindrical clusters as well.

  8. Pressure-Induced Electronic Transition in Black Phosphorus

    Science.gov (United States)

    Xiang, Z. J.; Ye, G. J.; Shang, C.; Lei, B.; Wang, N. Z.; Yang, K. S.; Liu, D. Y.; Meng, F. B.; Luo, X. G.; Zou, L. J.; Sun, Z.; Zhang, Y.; Chen, X. H.

    2015-10-01

    In a semimetal, both electrons and holes contribute to the density of states at the Fermi level. The small band overlaps and multiband effects engender novel electronic properties. We show that a moderate hydrostatic pressure effectively suppresses the band gap in the elemental semiconductor black phosphorus. An electronic topological transition takes place at approximately 1.2 GPa, above which black phosphorus evolves into a semimetal state that is characterized by a colossal positive magnetoresistance and a nonlinear field dependence of Hall resistivity. The Shubnikov-de Haas oscillations detected in magnetic field reveal the complex Fermi surface topology of the semimetallic phase. In particular, we find a nontrivial Berry phase in one Fermi surface that emerges in the semimetal state, as evidence of a Dirac-like dispersion. The observed semimetallic behavior greatly enriches the material property of black phosphorus and sets the stage for the exploration of novel electronic states in this material.

  9. Electron rescattering at metal nanotips induced by ultrashort laser pulses

    OpenAIRE

    Wachter, Georg; Lemell, Christoph; Burgdoerfer, Joachim

    2013-01-01

    We theoretically investigate the interaction of moderate intensity near-infrared few cycle laser pulses with nano-scale metal tips. Local field enhancement in a nanometric region around the tip apex triggers coherent electron emission on the nanometer length and femtosecond time scale. The quantum dynamics at the surface are simulated with time-dependent density functional theory (TDDFT) and interpreted based on the simple man's model. We investigate the dependence of the emitted electron spe...

  10. Electron gas induced in SrTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Han, E-mail: fuxxx254@umn.edu; Reich, K. V.; Shklovskii, B. I. [University of Minnesota, Fine Theoretical Physics Institute (United States)

    2016-03-15

    This mini-review is dedicated to the 85th birthday of Prof. L.V. Keldysh, from whom we have learned so much. In this paper, we study the potential and electron density depth profiles in surface accumulation layers in crystals with a large and nonlinear dielectric response such as SrTiO{sub 3} (STO) in the cases of planar, spherical, and cylindrical geometries. The electron gas can be created by applying an induction D{sub 0} to the STO surface. We describe the lattice dielectric response of STO using the Landau–Ginzburg free energy expansion and employ the Thomas–Fermi (TF) approximation for the electron gas. For the planar geometry, we arrive at the electron density profile n(x) ∝ (x + d){sup –12/7}, where d ∝ D{sub 0}{sup –12/7}. We extend our results to overlapping electron gases in GTO/STO/GTO heterojunctions and electron gases created by spill-out from NSTO (heavily n-type doped STO) layers into STO. Generalization of our approach to a spherical donor cluster creating a big TF atom with electrons in STO brings us to the problem of supercharged nuclei. It is known that for an atom with a nuclear charge Ze where Z > 170, electrons collapse onto the nucleus, resulting in a net charge Zn < Z. Here, instead of relativistic physics, the collapse is caused by the nonlinear dielectric response. Electrons collapse into the charged spherical donor cluster with radius R when its total charge number Z exceeds the critical value Z{sub c} ≈ R/a, where a is the lattice constant. The net charge eZ{sub n} grows with Z until Z exceeds Z* ≈ (R/a){sup 9/7}. After this point, the charge number of the compact core Z{sub n} remains ≈ Z*, with the rest Z* electrons forming a sparse TF atom with it. We extend our studies of collapse to the case of long cylindrical clusters as well.

  11. Electron-induced chemistry in microhydrated sulfuric acid clusters

    Directory of Open Access Journals (Sweden)

    J. Lengyel

    2017-11-01

    Full Text Available We investigate the mixed sulfuric acid–water clusters in a molecular beam experiment with electron attachment and negative ion mass spectrometry and complement the experiment by density functional theory (DFT calculations. The microhydration of (H2SO4m(H2On clusters is controlled by the expansion conditions, and the electron attachment yields the main cluster ion series (H2SO4m(H2OnHSO4− and (H2OnH2SO4−. The mass spectra provide an experimental evidence for the onset of the ionic dissociation of sulfuric acid and ion-pair (HSO4−  ⋅  ⋅  ⋅  H3O+ formation in the neutral H2SO4(H2On clusters with n ≥ 5 water molecules, in excellent agreement with the theoretical predictions. In the clusters with two sulfuric acid molecules (H2SO42(H2On this process starts as early as n ≥ 2 water molecules. The (H2SO4m(H2OnHSO4− clusters are formed after the dissociative electron attachment to the clusters containing the (HSO4−  ⋅  ⋅  ⋅  H3O+ ion-pair structure, which leads to the electron recombination with the H3O+ moiety generating H2O molecule and the H-atom dissociation from the cluster. The (H2OnH2SO4− cluster ions point to an efficient caging of the H atom by the surrounding water molecules. The electron-energy dependencies exhibit an efficient electron attachment at low electron energies below 3 eV, and no resonances above this energy, for all the measured mass peaks. This shows that in the atmospheric chemistry only the low-energy electrons can be efficiently captured by the sulfuric acid–water clusters and converted into the negative ions. Possible atmospheric consequences of the acidic dissociation in the clusters and the electron attachment to the sulfuric acid–water aerosols are discussed.

  12. Initiating the explosive decomposition of heavy metal azides by electron-beam-induced electric discharge

    Science.gov (United States)

    Oleshko, V. I.; Damamme, G.; Malys, D.; Lisitsyn, V. M.

    2009-10-01

    The explosive decomposition of heavy metal azides (HMAs) initiated by the electric (streamer) discharge induced by a nanosecond electron beam has been experimentally studied. A physical model is proposed that describes the initiation of an electron-beam-induced HMA explosion, which involves the formation of a strong electric field in a sample and its neutralization by a supersonic anode discharge. The propagating streamer front generates hot spots in a condensed reactive substance, from which the foci of explosive decomposition are formed.

  13. Electron paramagnetic resonance study on the ionizing radiation induced defects of the tooth enamel hydroxyapatite

    International Nuclear Information System (INIS)

    Oliveira, Liana Macedo de

    1995-01-01

    Hydroxyapatite is the main constituent of calcified tissues. Defects induced by ionizing radiations in this biomineral can present high stability and then, these are used as biological markers in radiological accidents, irradiated food identifying and geological and archaeological dating. In this work, paramagnetic centers induced on the enamel of the teeth by environmental ionizing radiation, are investigated by electron paramagnetic resonance (EPR). Decay thermal kinetic presents high complexity and shows the formation of different electron ligation energy centers and structures

  14. Electron postgrowth irradiation of platinum-containing nanostructures grown by electron-beam-induced deposition from Pt(PF3)4

    NARCIS (Netherlands)

    Botman, A.; Hagen, C.W.; Li, J.; Thiel, B.L.; Dunn, K.A.; Mulders, J.J.L.; Randolph, S.; Toth, M.

    2009-01-01

    The material grown in a scanning electron microscope by electron beam-induced deposition (EBID) using Pt(PF3)4 precursor is shown to be electron beam sensitive. The effects of deposition time and postgrowth electron irradiation on the microstructure and resistivity of the deposits were assessed by

  15. Simulation of wake potentials induced by relativistic proton bunches in electron clouds

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Fedor; Boine-Frankenheim, Oliver; Weiland, Thomas [Technische Universitaet Darmstadt (Germany). Institut fuer Theorie Elektromagnetischer Felder (TEMF)

    2012-07-01

    Electron clouds limit the intensity of modern high intensity hadron accelerators. Presently electron clouds are the main limiting factor for the LHC operation with 25 ns bunch trains. The bunches passing through an electron cloud induce a wake field. When the electron cloud density exceeds a certain threshold beam instabilities occur. The presence of electron clouds results in a shift of the synchronous phase, which increases if the bunch spacing is reduced. For LHC and SPS conditions we compare the longitudinal electron cloud wake potentials and stopping powers obtained using a simplified 2D electrostatic Particle-in-Cell code with fully electromagnetic simulations using VORPAL. In addition we analyze the wake fields induced by displaced or tilted bunches.

  16. Spin-controlled nanomechanics induced by single-electron tunneling.

    Science.gov (United States)

    Radić, D; Nordenfelt, A; Kadigrobov, A M; Shekhter, R I; Jonson, M; Gorelik, L Y

    2011-12-02

    We consider dc-electronic transport through a nanowire suspended between normal- and spin-polarized metal leads in the presence of an external magnetic field. We show that magnetomotive coupling between the electrical current through the nanowire and vibrations of the wire may result in self-excitation of mechanical vibrations. The self-excitation mechanism is based on correlations between the occupancy of the quantized electronic energy levels inside the nanowire and the velocity of the nanowire. We derive conditions for the occurrence of the instability and find stable regimes of mechanical oscillations. © 2011 American Physical Society

  17. Advanced ion beam analysis of materials using ion-induced fast electron

    Energy Technology Data Exchange (ETDEWEB)

    Kudo, Hiroshi; Tanabe, Atsushi; Ishihara, Toyoyuki [Tsukuba Univ., Ibaraki (Japan)] [and others

    1997-03-01

    Recent progress in the study of high-energy shadowing effect using ion-induced electron spectroscopy is reported with emphasis on a possibility of determination of local electronic structure in solids, which has been a difficult problem to approach with other experimental techniques. We demonstrate real-space determination of covalent-bond electron distribution in Si crystal. The analysis technique may provide a new field of ion beam analysis of solids. (author)

  18. Estimation of Airborne Radioactivity Induced by 8-GeV-Class Electron LINAC Accelerator.

    Science.gov (United States)

    Asano, Yoshihiro

    2017-10-01

    Airborne radioactivity induced by high-energy electrons from 6 to 10 GeV is estimated by using analytical methods and the Monte Carlo codes PHITS and FLUKA. Measurements using a gas monitor with a NaI(Tl) scintillator are carried out in air from a dump room at SACLA, an x-ray free-electron laser facility with 7.8-GeV electrons and are compared to the simulations.

  19. Quantum electron transfer processes induced by thermo-coherent ...

    Indian Academy of Sciences (India)

    WINTEC

    ordinate analysis gave a quantitative estimate of the rate of the outer sphere electron transfer in solution phase5,6 corresponding to the terms of the thermal average Franck–Condon (FC) factor.16,20–22. This classical high temperature limiting expression of the non-adiabatic ET rate corresponds to the continuous dielectric ...

  20. Defects induced in cerium dioxide single crystals by electron irradiation

    Science.gov (United States)

    Costantini, Jean-Marc; Miro, Sandrine; Touati, Nadia; Binet, Laurent; Wallez, Gilles; Lelong, Gérald; Guillaumet, Maxime; Weber, William J.

    2018-01-01

    Micro-Raman spectroscopy, X-band electron paramagnetic resonance (EPR) spectroscopy, and UV-visible optical absorption spectroscopy were used to study the damage production in cerium dioxide (CeO2) single crystals by electron irradiation for three energies (1.0, 1.4, and 2.5 MeV). The Raman-active T2g peak was left unchanged after 2.5-MeV electron irradiation at a high fluence. This shows that no structural modifications occurred for the cubic fluorite structure. UV-visible optical absorption spectra exhibited a characteristic sub band-gap tail for 1.4-MeV and 2.5-MeV energies, but not for 1.0 MeV. Narrow EPR lines were recorded near liquid-helium temperature after 2.5-MeV electron irradiation; whereas no such signal was found for the virgin un-irradiated crystal or after 1.0-MeV irradiation for the same fluence. The angular variation of these lines in the {111} plane revealed a weak g-factor anisotropy assigned to Ce3+ ions (with the 4f1 configuration) in a high-symmetry local environment. It is concluded that Ce3+ ions may be produced by a reduction resulting from the displacement damage process. However, no evidence of F+ or F0 center or hole center formation due to irradiation was found from the present EPR and optical absorption spectra.

  1. Pressure induced phase transition behaviour in-electron based ...

    Indian Academy of Sciences (India)

    The rare-earth and actinide based compounds are endowed with several exotic physical and chemical properties due to the presence of -electrons. These properties exhibit interesting changes under the action of various thermodynamic fields and hence continues to be a subject of extensive research. For instance, under ...

  2. Electronically induced nuclear transitions - temperature dependence and Rabi oscillations

    CERN Document Server

    Niez, J J

    2002-01-01

    This paper deals with a nucleus electromagnetically coupled with the bound states of its electronic surroundings. It describes the temperature dependence of its dynamics and the onset of potential Rabi oscillations by means of a Master Equation. The latter is generalized in order to account for possible strong resonances. Throughout the paper the approximation schemes are discussed and tested. (authors)

  3. Volume changes in glass induced by an electron beam

    Czech Academy of Sciences Publication Activity Database

    Gavenda, T.; Gedeon, O.; Jurek, Karel

    2014-01-01

    Roč. 322, Mar (2014), s. 7-12 ISSN 0168-583X Institutional support: RVO:68378271 Keywords : borosilicate glass * electron irradiation * densification * alkali migration Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.124, year: 2014

  4. Destructive effects induced by the electron beam in scanning electron microscopy

    Science.gov (United States)

    Popescu, M. C.; Bita, B. I.; Banu, M. A.; Tomescu, R. M.

    2016-12-01

    The Scanning Electron Microscopy has been validated by its impressive imaging and reliable measuring as an essential characterization tool for a variety of applications and research fields. This paper is a comprehensive study dedicated to the undesirable influence of the accelerated electron beam associated with the dielectric materials, sensitive structures or inappropriate sample manipulation. Depending on the scanning conditions, the electron beam may deteriorate the investigated sample due to the extended focusing or excessive high voltage and probe current applied on vulnerable configurations. Our aim is to elaborate an instructive material for improved SEM visualization capabilities by overcoming the specific limitations of the technique. Particular examination and measuring methods are depicted along with essential preparation and manipulation procedures in order to protect the integrity of the sample. Various examples are mentioned and practical solutions are described in respect to the general use of the electron microscope.

  5. Photo-Induced Electron Spin Polarization in a Narrow Band Gap Semiconductor Nanostructure

    International Nuclear Information System (INIS)

    Peter, A. John; Lee, Chang Woo

    2012-01-01

    Photo-induced spin dependent electron transmission through a narrow gap InSb/InGa x Sb 1−x semiconductor symmetric well is theoretically studied using transfer matrix formulism. The transparency of electron transmission is calculated as a function of electron energy for different concentrations of gallium. Enhanced spin-polarized photon assisted resonant tunnelling in the heterostructure due to Dresselhaus and Rashba spin-orbit coupling induced splitting of the resonant level and compressed spin-polarization are observed. Our results show that Dresselhaus spin-orbit coupling is dominant for the photon effect and the computed polarization efficiency increases with the photon effect and the gallium concentration

  6. Bias dependence of synergistic radiation effects induced by electrons and protons on silicon bipolar junction transistors

    Science.gov (United States)

    Liu, Chaoming; Li, Xingji; Yang, Jianqun; Ma, Guoliang; Xiao, Liyi

    2015-06-01

    Bias dependence on synergistic radiation effects caused by 110 keV electrons and 170 keV protons on the current gain of 3DG130 NPN bipolar junction transistors (BJTs) is studied in this paper. Experimental results indicate that the influence induced by 170 keV protons is always enhancement effect during the sequential irradiation. However, the influence induced by 110 keV electrons on the BJT under various bias cases is different during the sequential irradiation. The transition fluence of 110 keV electrons is dependent on the bias case on the emitter-base junction of BJT.

  7. Enhanced acceleration of injected electrons in a laser-beat-wave-induced plasma channel.

    Science.gov (United States)

    Tochitsky, S Ya; Narang, R; Filip, C V; Musumeci, P; Clayton, C E; Yoder, R B; Marsh, K A; Rosenzweig, J B; Pellegrini, C; Joshi, C

    2004-03-05

    Enhanced energy gain of externally injected electrons by a approximately 3 cm long, high-gradient relativistic plasma wave (RPW) is demonstrated. Using a CO2 laser beat wave of duration longer than the ion motion time across the laser spot size, a laser self-guiding process is initiated in a plasma channel. Guiding compensates for ionization-induced defocusing (IID) creating a longer plasma, which extends the interaction length between electrons and the RPW. In contrast to a maximum energy gain of 10 MeV when IID is dominant, the electrons gain up to 38 MeV energy in a laser-beat-wave-induced plasma channel.

  8. Electron-induced chemistry in microhydrated sulfuric acid clusters

    Czech Academy of Sciences Publication Activity Database

    Lengyel, Jozef; Pysanenko, Andriy; Fárník, Michal

    2017-01-01

    Roč. 17, č. 22 (2017), s. 14171-14180 ISSN 1680-7324 R&D Projects: GA ČR(CZ) GA17-04068S Grant - others:Austrian Science Fund (FWF)(AT) M1983-N34 Institutional support: RVO:61388955 Keywords : induced aerosol formation * particle formation * atmospheric implication Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry

  9. Electron beam induced modification of poly(ethylene terephthalate) films

    International Nuclear Information System (INIS)

    Vasiljeva, I.V.; Mjakin, S.V.; Makarov, A.V.; Krasovsky, A.N.; Varlamov, A.V.

    2006-01-01

    Electron beam processing of poly(ethylene terephthalate) (PET) films is found to promote significant changes in the melting heat, intrinsic viscosity and polymer film-liquid (water, isooctane and toluene) boundary surface tension. These properties are featured with several maximums depending on the absorbed dose and correlating with the modification of PET surface functionality. Studies using adsorption of acid-base indicators and IR-spectroscopy revealed that the increase of PET surface hydrophilicity is determined by the oxidation of methylene and methyne groups. Electron beam treatment of PET films on the surface of N-vinylpyrrolidone aqueous solution provided graft copolymerization with this comonomer at optimum process parameters (energy 700 keV, current 1 mA, absorbed dose 50 kGy)

  10. Momentum distribution dependence of induced electron-cyclotron emission

    International Nuclear Information System (INIS)

    Ziebell, L.F.; Dillenburg, D.

    1983-01-01

    The dependence of the electron-cyclotron wave amplification in an inhomogeneous plasma slab on the electron momentum distribution is investigated. Two types of distributions are considered, both featuring a loss cone and a Maxwellian component. It is shown that the perpendicular emission at the fundamental frequency is in general greatly reduced by the presence of a Maxwellian component and situations occur in which a layer in the slab very effectively absorbs all the radiation amplified elsewhere. The transition from the pure loss cone to the pure Maxwellian case is accompanied by a peculiar behaviour of the dielectric tensor components, which may invalidate the geometrical optics approximation in the calculation of the emission and the commonly held belief that the real part of the refractive index is insensitive to the shape of the momentum distribution function. (Author) [pt

  11. Radiation and thermal induced transformation in glassy chalcogenides using electron microscope

    International Nuclear Information System (INIS)

    Maged, A.F.

    1993-01-01

    Electron microscope is used to characterize the types of thermally induced transformations which occur in the chalcogenide glasses Si 20 Te 40 As 30 Ge 10 Si 12 Te 48 As 30 Ge 10 and Si 10 Te 50 As 30 Ge 10 . Beam heating in the electron microscope was used to observe directly the thermally induced transformations in amorphous thin films. A solid-fluid transition (softening) was observed in all compositions. Experimental evidence indicated that crystallization can be induced in the three compositions. No response to gamma radiation (up to 500 KGy) was observed in the structure of these compositions. 8 figs

  12. 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.

  13. Electron irradiation-induced nanocrystallization of amorphous Fe85B15 alloy: Evidence for athermal nature

    International Nuclear Information System (INIS)

    Qin, W.; Nagase, T.; Umakoshi, Y.

    2009-01-01

    Nanocrystallization of amorphous alloys induced by electronic energy deposition has been frequently reported in recent years. In this paper, the crystallization of amorphous Fe 85 B 15 alloy was performed by electron irradiation with 2 MeV electrons up to a flux of 4.0 x 10 24 m -2 s -1 . It was found that at 298 K, nanocrystalline Fe-B intermetallic phases formed prior to α-Fe phase, while at 463 K, only the α-Fe phase was observed. This phenomenon cannot be interpreted in terms of the electron-beam heating, but may be attributed to the irradiation-induced increases in the short-range order and atomic diffusivity. Theoretical analysis also showed that the maximum-temperature rise driven by beam heating is much lower than that required for thermal crystallization. Our work offers strong evidence that the irradiation-induced crystallization in amorphous alloys is not a thermal activation process

  14. PP-EPDM thermoplastic vulcanisates (TPVs by electron induced reactive processing

    Directory of Open Access Journals (Sweden)

    2009-11-01

    Full Text Available Reactive processing combines melt mixing process and chemical reaction simultaneously. TPVs are produced by such reactive processing. Polymer modification with high energy electrons is based on generation of excited atoms or molecules and ions for subsequent molecular changes via radical induced chemical reactions. In the present study, electron induced reactive processing is used for the development of TPVs. A 1.5 MeV electron accelerator was directly coupled to an internal mixer in order to induce chemical reactions by energy input via high energy electrons under dynamic conditions of melt mixing of polypropylene (PP and ethylene propylene diene monomer rubber (EPDM. The influence of absorbed dose (25 to 100 kGy as well as electron energy (1.5 and 0.6 MeV and electron treatment time (15 to 60 s have been studied. Increased values of both tensile strength and elongation at break of the TPVs indicate in-situ compatibilisation of PP and EPDM as well as cross-linking in the EPDM phase upon electron induced reactive processing. Dynamic mechanical analyses showed a decrease in value of glass transition temperature peak of EPDM in tangent delta curve with increasing dose. This also indicates higher degree of cross-linking in EPDM phase, which is further supported by a gel content that is higher than the EPDM content itself in the blend.

  15. Low-energy electron irradiation induced top-surface nanocrystallization of amorphous carbon film

    Science.gov (United States)

    Chen, Cheng; Fan, Xue; Diao, Dongfeng

    2016-10-01

    We report a low-energy electron irradiation method to nanocrystallize the top-surface of amorphous carbon film in electron cyclotron resonance plasma system. The nanostructure evolution of the carbon film as a function of electron irradiation density and time was examined by transmission electron microscope (TEM) and Raman spectroscopy. The results showed that the electron irradiation gave rise to the formation of sp2 nanocrystallites in the film top-surface within 4 nm thickness. The formation of sp2 nanocrystallite was ascribed to the inelastic electron scattering in the top-surface of carbon film. The frictional property of low-energy electron irradiated film was measured by a pin-on-disk tribometer. The sp2 nanocrystallized top-surface induced a lower friction coefficient than that of the original pure amorphous film. This method enables a convenient nanocrystallization of amorphous surface.

  16. Electron rescattering at metal nanotips induced by ultrashort laser pulses

    OpenAIRE

    Wachter, Georg; Lemell, Christoph; Burgdörfer, Joachim; Schenk, Markus; Krüger, Michael; Hommelhoff, Peter

    2012-01-01

    We report on the first investigation of plateau and cut-off structures in photoelectron spectra from nano-scale metal tips interacting with few-cycle near-infrared laser pulses. These hallmarks of electron rescattering, well-known from atom-laser interaction in the strong-field regime, appear at remarkably low laser intensities with nominal Keldysh parameters of the order of $\\gtrsim 10$. Quantum and quasi-classical simulations reveal that a large field enhancement near the tip and the increa...

  17. Helium induced fine structure in the electronic spectra of anthracene derivatives doped into superfluid helium nanodroplets

    International Nuclear Information System (INIS)

    Pentlehner, D.; Slenczka, A.

    2015-01-01

    Electronic spectra of organic molecules doped into superfluid helium nanodroplets show characteristic features induced by the helium environment. Besides a solvent induced shift of the electronic transition frequency, in many cases, a spectral fine structure can be resolved for electronic and vibronic transitions which goes beyond the expected feature of a zero phonon line accompanied by a phonon wing as known from matrix isolation spectroscopy. The spectral shape of the zero phonon line and the helium induced phonon wing depends strongly on the dopant species. Phonon wings, for example, are reported ranging from single or multiple sharp transitions to broad (Δν > 100 cm −1 ) diffuse signals. Despite the large number of example spectra in the literature, a quantitative understanding of the helium induced fine structure of the zero phonon line and the phonon wing is missing. Our approach is a systematic investigation of related molecular compounds, which may help to shed light on this key feature of microsolvation in superfluid helium droplets. This paper is part of a comparative study of the helium induced fine structure observed in electronic spectra of anthracene derivatives with particular emphasis on a spectrally sharp multiplet splitting at the electronic origin. In addition to previously discussed species, 9-cyanoanthracene and 9-chloroanthracene will be presented in this study for the first time

  18. Poverty, Homelessness, and Family Break-Up.

    Science.gov (United States)

    Shinn, Marybeth; Gibbons-Benton, Jessica; Brown, Scott R

    This study examines the extent and correlates of family separations in families experiencing homelessness. Of 2,307 parents recruited in family shelters across 12 sites, a tenth were separated from partners and a quarter from one or more children. Additional separations before and after shelter entry and reasons, from parents' perspectives, were documented in qualitative interviews with a subsample of 80 parents. Separations were associated with economic hardship, shelter conditions, and family characteristics.

  19. Poverty, Homelessness, and Family Break-Up

    OpenAIRE

    Shinn, Marybeth; Gibbons-Benton, Jessica; Brown, Scott R.

    2015-01-01

    This study examines the extent and correlates of family separations in families experiencing homelessness. Of 2,307 parents recruited in family shelters across 12 sites, a tenth were separated from partners and a quarter from one or more children. Additional separations before and after shelter entry and reasons, from parents’ perspectives, were documented in qualitative interviews with a subsample of 80 parents. Separations were associated with economic hardship, shelter conditions, and fami...

  20. Determination of low-energy ion-induced electron yields from thin carbon foils

    International Nuclear Information System (INIS)

    Allegrini, Frederic; Wimmer-Schweingruber, Robert F.; Wurz, Peter; Bochsler, Peter

    2003-01-01

    Ion beams crossing thin carbon foils can cause electron emission from the entrance and exit surface. Thin carbon foils are used in various types of time-of-flight (TOF) mass spectrometers to produce start pulses for TOF measurements. The yield of emitted electrons depends, among other parameters, on the energy of the incoming ion and its mass, and it has been experimentally determined for a few projectile elements. The electron emission yield is of great importance for deriving abundance ratios of elements and isotopes in space plasmas using TOF mass spectrometers. We have developed a detector for measuring ion-induced electron yields, and we have extended the electron yield measurements for oxygen to energies relevant for solar wind research. We also present first measurements of the carbon foil electron emission yield for argon and iron in the solar wind energy range

  1. Approaches to modelling irradiation-induced processes in transmission electron microscopy.

    Science.gov (United States)

    Skowron, Stephen T; Lebedeva, Irina V; Popov, Andrey M; Bichoutskaia, Elena

    2013-08-07

    The recent progress in high-resolution transmission electron microscopy (HRTEM) has given rise to the possibility of in situ observations of nanostructure transformations and chemical reactions induced by electron irradiation. In this article we briefly summarise experimental observations and discuss in detail atomistic modelling of irradiation-induced processes in HRTEM, as well as mechanisms of such processes recognised due to modelling. Accurate molecular dynamics (MD) techniques based on first principles or tight-binding models are employed in the analysis of single irradiation-induced events, and classical MD simulations are combined with a kinetic Monte Carlo algorithm to simulate continuous irradiation of nanomaterials. It has been shown that sulphur-terminated graphene nanoribbons are formed inside carbon nanotubes as a result of an irradiation-selective chemical reaction. The process of fullerene formation in HRTEM during continuous electron irradiation of a small graphene flake has been simulated, and mechanisms driving this transformation analysed.

  2. Compositional changes in industrial hemp biomass (Cannabis sativa L.) induced by electron beam irradiation Pretreatment

    International Nuclear Information System (INIS)

    Sung, Yong Joo; Shin, Soo-Jeong

    2011-01-01

    The effects of electron beam irradiation on chemical decomposition of industrial hemp biomass were evaluated at doses of 150, 300, and 450 kGy. The quantity of decomposed components was indirectly estimated by measuring changes in alkaline extraction. The more severe degradation of structural components induced by higher irradiation doses resulted in larger amounts of alkaline extract. Carbohydrate compositional analysis using 1 H-NMR spectroscopy was applied to quantitatively investigate changes in the polysaccharides of the industrial hemp. The xylose peak intensity in the NMR spectra decreased with increasing electron irradiation dose, indicating that xylan was more sensitive to electron beam irradiation than cellulose. -- Highlights: → The more severe degradation of structural components induced by higher irradiation. → Carbohydrate analysis was applied to quantitatively investigate changes in the industrial hemp. → Xylan was more sensitive to electron beam irradiation than cellulose.

  3. Effect of chemical structure on electron beam-induced decomposition of onium salts

    International Nuclear Information System (INIS)

    Hult, A.; Sundell, P.E.

    1990-01-01

    This work has been focused on the reduction of iodonium and sulfonium salts by organic free radicals or solvated electrons resulting in a Broensted (protonic) acid or a carbenium ion capable of initiating the cationic polymerization of vinyl ethers. An increased knowledge of the interplay between modes of activation, onium salt structure and the vinyl ether structure have been obtained. Gamma ray induced reduction of the onium salts by free radicals or solvated electrons revealed the importance of the onium salt structure for the redox reaction. Since the most important feature of high energy-induced cationic polymerization is the reduction of onium salt, the reactivity of a formulation (efficiency of the redox process) can be altered by: the onium salt (reduction potential), the monomer structure (radiation chemistry, yields of radicals and solvated electrons) and by the dose rate (yields of radicals and solvated electrons)

  4. Chemical changes induced on a TiO2 surface by electron bombardment

    International Nuclear Information System (INIS)

    Vergara, L.I.; Passeggi, M.C.G.; Ferron, J.

    2007-01-01

    We study the TiO 2 (Ti 4+ ) chemical reduction induced by electron bombardment using Auger electron spectroscopy and factor analysis. We show that the electron irradiation of a TiO 2 sample is characterized by the appearance of a lower Ti oxidation state, Ti 2 O 3 (Ti 3+ ), followed by a further deposition of carbon, which is present inevitably in the environment even under ultra-high vacuum conditions. The appearance of C over the surface is found to be a complex mechanism which affects the reduction process through passivation of the electron-induced oxygen desorption and formation of titanium carbide. For very high irradiation doses, we also found that the chemical changes on the surface are stopped due to the deposition of carbon in a graphitic form

  5. Theory of photon and electron induced reactions: Progress report, July 1, 1986-June 30, 1987

    International Nuclear Information System (INIS)

    Onley, D.S.; Wright, L.E.

    1988-07-01

    During the third year of our three-year contract from the Department of Energy, we have made considerable progress or have completed our studies on the following aspects of the general investigation of electron and photon induced reactions; photo- and electro-production of mesons; the radiation tail accompanying elastic electron scattering and pair production; studies involving relativistic shell model; and electrofission coincidence angular distributions. We will report on each of these developments in this paper

  6. On the mechanism of electron-beam induced phenomena in Na β-alumina

    International Nuclear Information System (INIS)

    Livshits, A.; Polak, M.

    1983-01-01

    A detailed mechanism is proposed for the emergence of sodium to the cleavage-face of the superionic conductor Na β-alumina during high dose electron bombardment. It is based on Auger electron spectroscopy measurements and optical microscope observations of the bombarded surface, and it involves both electromigration of the mobile Na + and fault formation at the cleavage-face resulting from induced internal stress. (author)

  7. Current-induced magnetoresistance oscillations in two-dimensional electron systems

    OpenAIRE

    Lei, X. L.

    2006-01-01

    Electric current-induced magnetoresistance oscillations recently discovered in two-dimensional electron systems are analyzed using a microscopic scheme for nonlinear magnetotransport direct controlled by the current. The magnetoresistance oscillations are shown to result from drift-motion assisted electron scatterings between Landau levels. The theoretical predictions not only reproduce all the main features observed in the experiments but also disclose other details of the phenomenon.

  8. Electron Impact Induced Reactions of Ethyl Acetate and Its Sulphur Analogues

    DEFF Research Database (Denmark)

    Egsgaard, Helge; Larsen, Elfinn; Carlsen, Lars

    1983-01-01

    The electron impact induced reactions of ethyl acetate and its sulphur analogues have been studied by application of collision activation mass spectrometry and isotopic labelling with H-2 and O-18. The [M-C2H4]+·, [M-CH3]+ and [M-H2O]+· were selected for detailed investigations.......The electron impact induced reactions of ethyl acetate and its sulphur analogues have been studied by application of collision activation mass spectrometry and isotopic labelling with H-2 and O-18. The [M-C2H4]+·, [M-CH3]+ and [M-H2O]+· were selected for detailed investigations....

  9. Heptachlor induced mitochondria-mediated cell death via impairing electron transport chain complex III

    International Nuclear Information System (INIS)

    Hong, Seokheon; Kim, Joo Yeon; Hwang, Joohyun; Shin, Ki Soon; Kang, Shin Jung

    2013-01-01

    Highlights: •Heptachlor inhibited mitochondrial electron transport chain complex III activity. •Heptachlor promoted generation of reactive oxygen species. •Heptachlor induced Bax activation. •Heptachlor induced mitochondria-mediated and caspase-dependent apoptosis. -- Abstract: Environmental toxins like pesticides have been implicated in the pathogenesis of Parkinson’s disease (PD). Epidemiological studies suggested that exposures to organochlorine pesticides have an association with an increased PD risk. In the present study, we examined the mechanism of toxicity induced by an organochlorine pesticide heptachlor. In a human dopaminergic neuroblastoma SH-SY5Y cells, heptachlor induced both morphological and functional damages in mitochondria. Interestingly, the compound inhibited mitochondrial electron transport chain complex III activity. Rapid generation of reactive oxygen species and the activation of Bax were then detected. Subsequently, mitochondria-mediated, caspase-dependent apoptosis followed. Our results raise a possibility that an organochlorine pesticide heptachlor can act as a neurotoxicant associated with PD

  10. Heptachlor induced mitochondria-mediated cell death via impairing electron transport chain complex III

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Seokheon; Kim, Joo Yeon; Hwang, Joohyun [Department of Molecular Biology, Sejong University, Seoul 143-747 (Korea, Republic of); Shin, Ki Soon [Department of Biology, Department of Life and Nanopharmaceutical Sciences, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Kang, Shin Jung, E-mail: sjkang@sejong.ac.kr [Department of Molecular Biology, Sejong University, Seoul 143-747 (Korea, Republic of)

    2013-08-09

    Highlights: •Heptachlor inhibited mitochondrial electron transport chain complex III activity. •Heptachlor promoted generation of reactive oxygen species. •Heptachlor induced Bax activation. •Heptachlor induced mitochondria-mediated and caspase-dependent apoptosis. -- Abstract: Environmental toxins like pesticides have been implicated in the pathogenesis of Parkinson’s disease (PD). Epidemiological studies suggested that exposures to organochlorine pesticides have an association with an increased PD risk. In the present study, we examined the mechanism of toxicity induced by an organochlorine pesticide heptachlor. In a human dopaminergic neuroblastoma SH-SY5Y cells, heptachlor induced both morphological and functional damages in mitochondria. Interestingly, the compound inhibited mitochondrial electron transport chain complex III activity. Rapid generation of reactive oxygen species and the activation of Bax were then detected. Subsequently, mitochondria-mediated, caspase-dependent apoptosis followed. Our results raise a possibility that an organochlorine pesticide heptachlor can act as a neurotoxicant associated with PD.

  11. Numerical simulation of inducing characteristics of high energy electron beam plasma for aerodynamics applications

    Science.gov (United States)

    Deng, Yongfeng; Jiang, Jian; Han, Xianwei; Tan, Chang; Wei, Jianguo

    2017-04-01

    The problem of flow active control by low temperature plasma is considered to be one of the most flourishing fields of aerodynamics due to its practical advantages. Compared with other means, the electron beam plasma is a potential flow control method for large scale flow. In this paper, a computational fluid dynamics model coupled with a multi-fluid plasma model is established to investigate the aerodynamic characteristics induced by electron beam plasma. The results demonstrate that the electron beam strongly influences the flow properties, not only in the boundary layers, but also in the main flow. A weak shockwave is induced at the electron beam injection position and develops to the other side of the wind tunnel behind the beam. It brings additional energy into air, and the inducing characteristics are closely related to the beam power and increase nonlinearly with it. The injection angles also influence the flow properties to some extent. Based on this research, we demonstrate that the high energy electron beam air plasma has three attractive advantages in aerodynamic applications, i.e. the high energy density, wide action range and excellent action effect. Due to the rapid development of near space hypersonic vehicles and atmospheric fighters, by optimizing the parameters, the electron beam can be used as an alternative means in aerodynamic steering in these applications.

  12. Aluminum/vacuum multilayer configuration for spatial high-energy electron shielding via electron return effects induced by magnetic field.

    Science.gov (United States)

    Chen, Tuo; Tang, Xiaobin; Chen, Feida; Ni, Minxuan; Huang, Hai; Zhang, Yun; Chen, Da

    2017-06-26

    Radiation shielding of high-energy electrons is critical for successful space missions. However, conventional passive shielding systems exhibit several limitations, such as heavy configuration, poor shielding ability, and strong secondary bremsstrahlung radiation. In this work, an aluminum/vacuum multilayer structure was proposed based on the electron return effects induced by magnetic field. The shielding property of several configurations was evaluated by using the Monte Carlo method. Results showed that multilayer systems presented improved shielding ability to electrons, and less secondary x-ray transmissions than those of conventional systems. Moreover, the influences of magnetic flux density and number of layers on the shielding property of multilayer systems were investigated using a female Chinese hybrid reference phantom based on cumulative dose. In the case of two aluminum layers, the cumulative dose in a phantom gradually decreased with increasing magnetic flux density. The maximum decline rate was found within 0.4-1 Tesla. With increasing layers of configuration, the cumulative dose decreased and the shielding ability improved. This research provides effective shielding measures for future space radiation protection in high-energy electron environments.

  13. Tunable electron heating induced giant magnetoresistance in the high mobility GaAs/AlGaAs 2D electron system.

    Science.gov (United States)

    Wang, Zhuo; Samaraweera, R L; Reichl, C; Wegscheider, W; Mani, R G

    2016-12-07

    Electron-heating induced by a tunable, supplementary dc-current (I dc ) helps to vary the observed magnetoresistance in the high mobility GaAs/AlGaAs 2D electron system. The magnetoresistance at B = 0.3 T is shown to progressively change from positive to negative with increasing I dc , yielding negative giant-magnetoresistance at the lowest temperature and highest I dc . A two-term Drude model successfully fits the data at all I dc and T. The results indicate that carrier heating modifies a conductivity correction σ 1 , which undergoes sign reversal from positive to negative with increasing I dc , and this is responsible for the observed crossover from positive- to negative- magnetoresistance, respectively, at the highest B.

  14. Two contrasting modes of continental break-up associated with the formation of the Paleo- and Neo-Tethys in Iran: Implications for petrological and geodynamic evolution at a regional scale

    Science.gov (United States)

    Saccani, Emilio; Marroni, Michele; Pandolfi, Luca; Allahyari, Khalil; Azimzadeh, Zohreh

    2014-05-01

    In Iran, two partial ophiolitic sequences, which are broadly classifiable as "Continental Margin Ophiolite" (CMO), record the tectono-magmatic processes that occur during the continental break-up preceding oceanic basin formation. They are represented by: (1) the Early Carboniferous Misho Mafic Complex (NW Iran) and (2) the Triassic sequences in the Kermanshah ophiolite (Zagros Belt) that are associated with the formation of the Paleo- and Neo-Tethys, respectively. Both CMO sequences consist of gabbros, sheeted dykes and basaltic lavas. Moreover, the Kermanshah CMO also includes exhumed sub-continental mantle lherzolites. Both sequences include rocks showing variable incompatible element enrichments, ranging from N-MORB to E-MORB, P-MORB and alkaline basalt compositions and are interpreted to have formed from partial melting a depleted MORB-type mantle source (DMM) metasomatized by variable proportions of plume-type, enriched components. Nonetheless, geological evidence and petrogenetic modeling suggest that the continental break-up of the Paleo- and Neo-Tethys occurred in two quite different ways. The initial rift-drift tectonics of the Paleo-Tethys was triggered by a mantle plume activity and was strongly affected by plume-related magmatism and associated lithospheric weakening at a regional scale. This conclusion is consistent with the models proposed for the Paleo-Tethys margins in central-eastern Asia. In contrast, the initial rift-drift tectonics of the Neo-Tethys was characterized by a type of rifted margin, which is intermediate between the amagmatic type (Ligurian Tethys type) and the magmatic, plume-influenced type. Indeed, likewise the Ligurian Tethys, rifting occurred through passive (possibly, asymmetric) extension, which led to the exhumation of the sub-continental mantle. Meanwhile, high Sm/Yb rocks formed at the continent-ocean transition zone by partial melting of a DMM source locally bearing sub-continental garnet-pyroxenite relics. However, in

  15. Radioprotective efficacy of bisarylidene cyclopentanone on electron beam radiation induced oxidative stress in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Darshan Raj, C.G.; Sarojini, B.K.; Musthafa Khaleel, V.; Ramesh, S.R.; Ramakrishna, M.K.; Narayana, B.; Sanjeev, Ganesh

    2010-01-01

    Present study was carried out for evaluating the radioprotective effect of bischalcone (2E, 5E) - 2,5-bis (3-methoxy-4-hydroxy-benzylidene) cyclopentanone (curcumin analog (CA)), on electron beam radiation induced oxidative stress in Drosophila melanogaster adults. The oxidative stress markers and antioxidants included superoxide dismutase (SOD) and catalase (CAT). The oxidative stress was induced at 1.5 Gy. (author)

  16. Electron emission induced by resonant coherent ion-surface interaction at grazing incidence

    International Nuclear Information System (INIS)

    Garcia de Abajo, F.J.; Ponce, V.H.; Echenique, P.M.

    1992-01-01

    A new spectroscopy based on the resonant coherently induced electron loss to the continuum in ion-surface scattering under grazing incidence is proposed. A series of peaks, corresponding to the energy differences determined by the resonant interaction with the rows of atoms in the surface, is predicted to appear in the energy distribution of electrons emitted from electronic states bound to the probe. Calculations for MeV He + ions scattered at a W(001) surface along the left-angle 100 right-angle direction with a glancing angle of 0--2 mrad show a total yield close to 1

  17. Electron-beam induced current characterization of back-surface field solar cells using a chopped scanning electron microscope beam

    Science.gov (United States)

    Luke, K. L.; Cheng, L.-J.

    1984-01-01

    A chopped electron beam induced current (EBIC) technique for the chacterization of back-surface field (BSF) solar cells is presented. It is shown that the effective recombination velocity of the low-high junction forming the back-surface field of BSF cells, in addition to the diffusion length and the surface recombination velocity of the surface perpendicular to both the p-n and low-high junctions, can be determined from the data provided by a single EBIC scan. The method for doing so is described and illustrated. Certain experimental considerations taken to enhance the quality of the EBIC data are also discussed.

  18. Electrochemiluminescence of coumarin derivatives induced by injection of hot electrons into aqueous electrolyte solution

    International Nuclear Information System (INIS)

    Helin, Mika; Jiang, Qinghong; Ketamo, Hanna; Hakansson, Markus; Spehar, Anna-Maria; Kulmala, Sakari; Ala-Kleme, Timo

    2005-01-01

    Hot electrons can be injected from conductor/insulator/electrolyte (C/I/E) junctions into an aqueous electrolyte solution by cathodic pulse-polarization of the electrode. Injected hot electrons induce electrogenerated chemiluminescence of various luminophores including coumarins in fully aqueous solutions. This is based on the tunnel emission of hot electrons into aqueous electrolyte solution, which can result in the generation of hydrated electrons as reducing mediators. These tunnel-emitted electrons allow also the production of highly oxidizing radicals from added precursors. This work shows that coumarin derivatives are suitable candidates as ECL labels for bioaffinity assays or other analytical applications in which detection is based on the ECL of pulse-polarized C/I/E tunnel-emission electrodes in fully aqueous solutions. The mechanisms of the ECL of coumarins are discussed and the analytical applicability of the ECL of three coumarin derivatives is studied

  19. Electron-beam-induced segregation in InGaN/GaN multiple-quantum wells

    International Nuclear Information System (INIS)

    O'Neill, J.P.; Ross, I.M.; Cullis, A.G.; Wang, T.; Parbrook, P.J.

    2003-01-01

    We report a study of the morphology and composition of In x Ga 1-x N/GaN multiple-quantum-well structures and their sensitivity to electron-beam damage. We have employed high-resolution transmission electron microscopy, energy dispersive x-ray analysis, and scanning transmission electron microscopy. Microstructural analysis was performed to investigate the dynamical effects of electron-beam irradiation on the relative indium distribution within the quantum wells. Exposure to relatively low incident beam illumination, corresponding to current densities at the specimen of ∼100 pA/cm 2 , was found to induce significant nanoclustering of indium within the multiple-quantum wells. These findings highlight the need for caution when reporting the presence of indium-rich clusters within InGaN/GaN multiple-quantum wells studied in the transmission electron microscope

  20. Distorted wave calculations for electron loss process induced by bare ion impact on biological targets

    International Nuclear Information System (INIS)

    Monti, J.M.; Tachino, C.A.; Hanssen, J.; Fojón, O.A.; Galassi, M.E.; Champion, C.; Rivarola, R.D.

    2014-01-01

    Distorted wave models are employed to investigate the electron loss process induced by bare ions on biological targets. The two main reactions which contribute to this process, namely, the single electron ionization as well as the single electron capture are here studied. In order to further assess the validity of the theoretical descriptions used, the influence of particular mechanisms are studied, like dynamic screening for the case of electron ionization and energy deposition on the target by the impacting projectile for the electron capture one. Results are compared with existing experimental data. - Highlights: ► Distorted wave models are used to investigate ion-molecule collisions. ► Differential and total cross-sections for capture and ionization are evaluated. ► The influence of dynamic screening is determined. ► Capture reaction dominates the mean energy deposited by the projectile on the target

  1. Electron-beam-irradiation-induced crystallization of amorphous solid phase change materials

    Science.gov (United States)

    Zhou, Dong; Wu, Liangcai; Wen, Lin; Ma, Liya; Zhang, Xingyao; Li, Yudong; Guo, Qi; Song, Zhitang

    2018-04-01

    The electron-beam-irradiation-induced crystallization of phase change materials in a nano sized area was studied by in situ transmission electron microscopy and selected area electron diffraction. Amorphous phase change materials changed to a polycrystalline state after being irradiated with a 200 kV electron beam for a long time. The results indicate that the crystallization temperature strongly depends on the difference in the heteronuclear bond enthalpy of the phase change materials. The selected area electron diffraction patterns reveal that Ge2Sb2Te5 is a nucleation-dominated material, when Si2Sb2Te3 and Ti0.5Sb2Te3 are growth-dominated materials.

  2. Momentum mapping spectrometer for probing the fragmentation dynamics of molecules induced by keV electrons

    International Nuclear Information System (INIS)

    Singh, Raj; Bhatt, Pragya; Yadav, Namita; Shanker, R

    2011-01-01

    We describe a new experimental setup for studying the fragmentation dynamics of molecules induced by the impact of keV electrons using the well-known technique of recoil ion momentum spectroscopy. The apparatus consists of mainly a time- and position-sensitive multi-hit particle detector for ion analysis and a channel electron multiplier detector for detecting the ejected electrons. Different components of the setup and the relevant electronics for data acquisition are described in detail with their working principles. In order to verify the reliable performance of the setup, we have recorded the collision-induced ionic spectra of the CO 2 molecule by the impact of keV electrons. Information about the ion pairs of CO + :O + , C + :O + and O + :O + resulting from dissociative ionizing collisions of 20 and 26 keV electrons with a dilute gaseous target of CO 2 molecules has been obtained. Under conditions of the present experiment, the momentum resolutions of the spectrometer for the combined momenta of CO + and O + ions in the direction of the time-of-flight axis and perpendicular to the direction of an electron beam are found to be 10.0 ± 0.2 and 15.0 ± 0.3 au, respectively

  3. Monte-Carlo simulations of secondary electron emission from CsI, induced by 1-10 keV X-rays and electrons

    International Nuclear Information System (INIS)

    Akkerman, A.; Gibrekhterman, A.; Breskin, A.; Chechik, R.

    1992-05-01

    A model for electron transport and emission in CsI is proposed. It is based on theoretically calculated microscopic cross-sections for electron interaction with the nuclear and the electronic components of the solid. A Monte Carlo program based on this model was developed to simulate secondary electron emission induced by X-rays and electrons in the energy range of 1 to 10 keV. The calculated secondary emission yields agree with existing experimental data. The model provides all necessary characteristics for the design of radiation detectors based on secondary electron emission. It can be expanded to higher incident energies and other alkali halides. (author)

  4. Electron-induced chemistry of methyl chloride caged within amorphous solid water

    Science.gov (United States)

    Horowitz, Yonatan; Asscher, Micha

    2013-10-01

    The interaction of low energy electrons (1.0-25 eV) with methyl-chloride (CD3Cl) molecules, caged within Amorphous Solid Water (ASW) films, 10-120 monolayer (ML) thick, has been studied on top of a Ru(0001) substrate under Ultra High Vacuum (UHV) conditions. While exposing the ASW film to 3 eV electrons a static electric field up to 8 × 108 V/m is developed inside the ASW film due to the accumulation of trapped electrons that produce a plate capacitor voltage of exactly 3 V. At the same time while the electrons continuously strike the ASW surface, they are transmitted through the ASW film at currents of ca. 3 × 10-7 A. These electrons transiently attach to the caged CD3Cl molecules leading to C-Cl bond scission via Dissociative Electron Attachment (DEA) process. The electron induced dissociation cross sections and product formation rate constants at 3.0 eV incident electrons at ASW film thicknesses of 10 ML and 40 ML were derived from model simulations supported by Thermal Programmed Desorption (TPD) experimental data. For 3.0 eV electrons the CD3Cl dissociation cross section is 3.5 × 10-16 cm2, regardless of ASW film thickness. TPD measurements reveal that the primary product is deuterated methane (D3CH) and the minor one is deuterated ethane (C2D6).

  5. Proton induced X-ray emission and electron microscopy analysis of induced mutants of sorghum

    CSIR Research Space (South Africa)

    Mbambo, Z

    2014-01-01

    Full Text Available of elements in preferential accumulation tissues and entire changes in cellular localization. Transmission and scanning electron microscopy of the mutants resolved changes in size, shape, ultra-structure and packed cell volumes of protein- and starch bodies...

  6. Preliminary examination of induced radio activity in pepper by 10 MeV electron irradiation

    International Nuclear Information System (INIS)

    Furuta, Masakazu; Katayama, Tadashi; Ito, Norio; Mizohata, Akira; Matsunami, Tadao; Toratani, Hirokazu; Takeda, Atsuhiko

    1989-01-01

    β-ray measurement was performed on 10 MeV electron-irradiated black pepper and white pepper in order to reconfirm the wholesomeness of irradiated food and present unambiguous data to general consumers concerning about the induced radioactivity in the irradiated foods. From elemental composition of the samples and investigation of photonuclear reactions, several β-emmitters were listed up. But no radioactivity other than from natural sources was detected in the irradiated sample by β-ray counting with 2 π gass flow counter, suggesting that the induced β-emmitters in the irradiated sample was below the detection limit of its induced radioactivity. (author)

  7. Secondary-electron yield from Au induced by highly charged Ta ions

    Czech Academy of Sciences Publication Activity Database

    Krása, Josef; Láska, Leoš; Stöckli, M. P.; Fry, D.

    2001-01-01

    Roč. 173, - (2001), s. 281-286 ISSN 0168-583X R&D Projects: GA AV ČR IAA1010819 Institutional research plan: CEZ:AV0Z1010914 Keywords : highly charged ion-surface interaction * ion-induced electron emission * angle impact effect Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.041, year: 2001

  8. Charging effects during focused electron beam induced deposition of silicon oxide

    NARCIS (Netherlands)

    de Boer, Sanne K.; van Dorp, Willem F.; De Hosson, Jeff Th. M.

    2011-01-01

    This paper concentrates on focused electron beam induced deposition of silicon oxide. Silicon oxide pillars are written using 2, 4, 6, 8, 10-pentamethyl-cyclopenta-siloxane (PMCPS) as precursor. It is observed that branching of the pillar occurs above a minimum pillar height. The branching is

  9. Crosslinking of oriented polyethylene by electron beam radiation. Influence of morphology induced by drawing

    International Nuclear Information System (INIS)

    Aerle, N.A.J.M. van; Crevecoeur, G.; Lemstra, P.J.

    1988-01-01

    The influence of drawing on the crosslinking efficiency for electron beam radiation is reported for solution-crystallized ultra-high molecular weight polyethylene. A maximum in crosslinking efficiency is found at a draw ratio of approximately five, indicating an optimum morphology for inducing crosslinks during the hot-drawing process. (author)

  10. Electron Transfer and Collision Induced Dissociation of Non-Derivatized and Derivatized Desmosine and Isodesmosine

    NARCIS (Netherlands)

    Ongay, Sara; Hermans, Jos; Bruins, Andries P.; Nieuwendijk, Adrianus M. C. H.; Overkleeft, Hermen; Bischoff, Rainer

    Electron transfer dissociation (ETD) has attracted increasing interest due to its complementarity to collision-induced dissociation (CID). ETD allows the direct localization of labile post-translational modifications, which is of main interest in proteomics where differences and similarities between

  11. Probing Electron-Induced Bond Cleavage at the Single-Molecule Level Using DNA Origami Templates

    DEFF Research Database (Denmark)

    Keller, Adrian Clemens; Bald, Ilko; Rotaru, Alexandru

    2012-01-01

    specifically designed oligonucleotide targets that are attached to DNA origami templates. In this way, we use a highly selective approach to compare the efficiency of the electron-induced dissociation of a single disulfide bond with the more complex cleavage of the DNA backbone within a TT dinucleotide...

  12. Sequence dependence of electron-induced DNA strand breakage revealed by DNA nanoarrays

    DEFF Research Database (Denmark)

    Keller, Adrian; Rackwitz, Jenny; Cauët, Emilie

    2014-01-01

    sections for electron induced single strand breaks in specific 13 mer oligonucleotides we used atomic force microscopy analysis of DNA origami based DNA nanoarrays. We investigated the DNA sequences 5'-TT(XYX)3TT with X = A, G, C and Y = T, BrU 5-bromouracil and found absolute strand break cross sections...

  13. Enhanced Au induced lateral crystallization in electron-irradiated amorphous Ge on SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sakiyama, Shin; Kaneko, Takahiro; Ootsubo, Takanobu; Sakai, Takatsugu; Nakashima, Kazutoshi; Moto, Kenta; Yoneoka, Masashi; Takakura, Kenichiro; Tsunoda, Isao, E-mail: isao_tsunoda@kumamoto-nct.ac.jp

    2014-04-30

    We have investigated the low temperature of Au induced lateral crystallization of electron irradiated amorphous Ge on SiO{sub 2}/Si substrate. The reduction of the critical annealing time to cause the Au induced lateral crystallization is realized by high energy electron irradiation. In addition, the lateral crystallization region of the sample with electron irradiation has high crystalline quality as well as the sample without electron irradiation. We have speculated that the Au induced lateral crystallization of amorphous Ge on SiO{sub 2}/Si substrate was enhanced by electron irradiation, due to the introduction of point defects into amorphous Ge able to diffuse easily of Au atoms. - Highlights: • Au induced lateral crystallization of electron irradiated Ge is investigated. • Crystallization annealing time is significantly reduced. • High crystalline quality of lateral region was not changed by electron irradiation.

  14. SEM technique for imaging and measuring electronic transport in nanocomposites based on electric field induced contrast

    Science.gov (United States)

    Jesse, Stephen [Knoxville, TN; Geohegan, David B [Knoxville, TN; Guillorn, Michael [Brooktondale, NY

    2009-02-17

    Methods and apparatus are described for SEM imaging and measuring electronic transport in nanocomposites based on electric field induced contrast. A method includes mounting a sample onto a sample holder, the sample including a sample material; wire bonding leads from the sample holder onto the sample; placing the sample holder in a vacuum chamber of a scanning electron microscope; connecting leads from the sample holder to a power source located outside the vacuum chamber; controlling secondary electron emission from the sample by applying a predetermined voltage to the sample through the leads; and generating an image of the secondary electron emission from the sample. An apparatus includes a sample holder for a scanning electron microscope having an electrical interconnect and leads on top of the sample holder electrically connected to the electrical interconnect; a power source and a controller connected to the electrical interconnect for applying voltage to the sample holder to control the secondary electron emission from a sample mounted on the sample holder; and a computer coupled to a secondary electron detector to generate images of the secondary electron emission from the sample.

  15. Low-energy electron irradiation induced top-surface nanocrystallization of amorphous carbon film

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Cheng [Institute of Nanosurface Science and Engineering (INSE), Shenzhen University, Shenzhen 518060 (China); Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Fan, Xue, E-mail: fanx@szu.edu.cn [Institute of Nanosurface Science and Engineering (INSE), Shenzhen University, Shenzhen 518060 (China); Diao, Dongfeng, E-mail: dfdiao@szu.edu.cn [Institute of Nanosurface Science and Engineering (INSE), Shenzhen University, Shenzhen 518060 (China)

    2016-10-30

    Graphical abstract: Low-energy electron irradiation was proposed to nanocrystallize the top-surface of the as-deposited amorphous carbon film, and sp{sup 2} nanocrystallites formed in the film top-surface within 4 nm thickness. Display Omitted - Abstract: We report a low-energy electron irradiation method to nanocrystallize the top-surface of amorphous carbon film in electron cyclotron resonance plasma system. The nanostructure evolution of the carbon film as a function of electron irradiation density and time was examined by transmission electron microscope (TEM) and Raman spectroscopy. The results showed that the electron irradiation gave rise to the formation of sp{sup 2} nanocrystallites in the film top-surface within 4 nm thickness. The formation of sp{sup 2} nanocrystallite was ascribed to the inelastic electron scattering in the top-surface of carbon film. The frictional property of low-energy electron irradiated film was measured by a pin-on-disk tribometer. The sp{sup 2} nanocrystallized top-surface induced a lower friction coefficient than that of the original pure amorphous film. This method enables a convenient nanocrystallization of amorphous surface.

  16. Electron beam exposure mechanisms in hydrogen silsesquioxane investigated by vibrational spectroscopy and in-situ electron beam induced desorption

    Energy Technology Data Exchange (ETDEWEB)

    Olynick, D.L.; Cord, B.; Schipotinin, A.; Ogletree, D.F.; Schuck, P.J.

    2009-11-13

    Hydrogen Silsesquioxane (HSQ) is used as a high-resolution resist with resolution down below 10nm half-pitch. This material or materials with related functionalities could have widespread impact in nanolithography and nanoscience applications if the exposure mechanism was understood and instabilities controlled. Here we have directly investigated the exposure mechanism using vibrational spectroscopy (both Raman and Fourier transform Infrared) and electron beam desorption spectrocscopy (EBDS). In the non-networked HSQ system, silicon atoms sit at the corners of a cubic structure. Each silicon is bonded to a hydrogen atom and bridges 3 oxygen atoms (formula: HSiO3/2). For the first time, we have shown, via changes in the Si-H2 peak at ~;;2200 cm -1 in the Raman spectra and the release of SiHx products in EBID, that electron-bam exposed materials crosslinks via a redistribution reaction. In addition, we observe the release of significantly more H2 than SiH2 during EBID, which is indicative of additional reaction mechanisms. Additionally, we compare the behavior of HSQ in response to both thermal and electron-beam induced reactions.

  17. Beam-Induced Multipactoring and Electron-Cloud Effects in Particle Accelerators

    CERN Document Server

    Caspers, Friedhelm; Scandale, Walter; Zimmermann, F

    2009-01-01

    In the beam pipe of high-energy proton or positron accelerators an “electron cloud” can be generated by a variety of processes, e.g. by residual-gas ionization, by photoemission from synchrotron radiation, and, most importantly, by secondary emission via a beam-induced multipactoring process. The electron cloud commonly leads to a degradation of the beam vacuum by several orders of magnitude, to fast beam instabilities, to beam-size increases, and to fast or slow beam losses. At the Large Hadron Collider (LHC), the cloud electrons could also give rise to an additional heat load inside cold superconducting magnets. In addition to the direct heat deposition from incoherently moving electrons, a potential “magnetron effect” has been conjectured, where electrons would radiate coherently when moving in a strong magnetic field under the simultaneous influence of a beam-induced electric “wake” field that may become resonant with the cyclotron frequency. Electron-cloud effects are already being observed w...

  18. Structural changes and tribological performance of thermosetting polyimide induced by proton and electron irradiation

    International Nuclear Information System (INIS)

    Lv, Mei; Wang, Yanming; Wang, Qihua; Wang, Tingmei; Liang, Yongmin

    2015-01-01

    The structural changes and tribological performance of thermosetting polyimide were investigated by electron, proton or both combined irradiations at 25 keV in a ground-based simulation facility. Three forms of irradiations could lead to the formation of the carbonized layer on the polymer surface that could increase the hardness and adhesive force of the material. Proton irradiation induced more extensive changes in structure and friction behavior than electron irradiation by reason of the higher linear energy transfer value, and combined irradiation resulted in the largest impact, but which was less than the sum of the radiation effects of electron and proton. Moreover, the experimental results indicated that the changes in friction behavior are closely related with the carbonized layer, which was easily worn out in friction process and could introduce a shift from adhesion wear to three-body abrasive wear that reduced the wear rate and the friction coefficient. The friction process of irradiated samples could be divided into the initial stage and the steady stage. Three forms of irradiations all induced the high friction coefficient in the initial stage and the low friction coefficient in the steady stage, and the wear rate of the irradiated samples decreased in the order: electron irradiation>proton irradiation>combined irradiation. - Highlights: • Proton irradiation induced more extensive changes in structure and friction behavior than electron irradiation. • The effect of combined irradiation was less than that of the sum of electron and proton irradiation. • Three forms of irradiations all induced the high initial friction coefficient and the low steady-stage friction coefficient. • The initial friction stage means a fast-wearing adhesive process while the steady-state of the system is a three-body abrasion

  19. Evaluation of induced radioactivity in 10 MeV-electron irradiated spices, (1)

    International Nuclear Information System (INIS)

    Furuta, Masakazu; Katayama, Tadashi; Ito, Norio; Mizohata, Akira; Matsunami, Tadao; Shibata, Setsuko; Toratani, Hirokazu; Takeda, Atsuhiko.

    1994-01-01

    Black pepper, white pepper, red pepper, ginger and turmeric were irradiated with 10 MeV electrons from a linear accelerator to a dose of 100 kGy and radioactivity was measured in order to estimate induced radioactivity in the irradiated foods. Induced radioactivity could not be detected significantly by γ-ray spectrometry in the irradiated samples except for spiked samples which contain some photonuclear target nuclides in the list of photonuclear reactions which could produce radioactivity below 10 MeV. From the amount of observed radioactivities of short-lived photonuclear products in the spiked samples and calculation of H 50 according to ICRP Publication 30, it was concluded that the induced radioactivity and its biological effects in the 10 MeV electron-irradiated natural samples were negligible in comparison with natural radioactivity from 40 K contained in the samples. (author)

  20. A new route to nanoscale tomographic chemical analysis: Focused ion beam-induced auger electron spectrosocpy

    Science.gov (United States)

    Parvaneh, Hamed

    This research project is aimed to study the application of ion-induced Auger electron spectroscopy (IAES) in combination with the characteristics of focused ion beam (FIB) microscopy for performing chemical spectroscopy and further evaluate its potential for 3-dimensional chemical tomography applications. The mechanism for generation of Auger electrons by bombarding ions is very different from its electron induced counterpart. In the conventional electron-induced Auger electron spectroscopy (EAES), an electron beam with energy typically in the range 1-10kV is used to excite inner-shell (core) electrons of the solid. An electron from a higher electron energy state then de-excites to fill the hole and the extra energy is then transferred to either another electron, i.e. the Auger electron, or generation of an X-ray (photon). In both cases the emitting particles have charac-teristic energies and could be used to identify the excited target atoms. In IAES, however, large excitation cross sections can occur by promotion of in-ner shell electrons through crossing of molecular orbitals. Originally such phenomenological excitation processes were first proposed [3] for bi-particle gas phase collision systems to explain the generation of inner shell vacancies in violent collisions. In addition to excitation of incident or target atoms, due to a much heavier mass of ions compared to electrons, there would also be a substantial momentum transfer from the incident to the target atoms. This may cause the excited target atom to recoil from the lattice site or alternatively sputter off the surface with the possibility of de-excitation while the atom is either in motion in the matrix or traveling in vacuum. As a result, one could expect differences between the spectra induced by incident electrons and ions and interpretation of the IAE spectra requires separate consideration of both excitation and decay processes. In the first stage of the project, a state-of-the-art mass

  1. Exploring the temporally resolved electron density evolution in extreme ultra-violet induced plasmas

    International Nuclear Information System (INIS)

    Van der Horst, R M; Beckers, J; Nijdam, S; Kroesen, G M W

    2014-01-01

    We measured the electron density in an extreme ultra-violet (EUV) induced plasma. This is achieved in a low-pressure argon plasma by using a method called microwave cavity resonance spectroscopy. The measured electron density just after the EUV pulse is 2.6 × 10 16  m −3 . This is in good agreement with a theoretical prediction from photo-ionization, which yields a density of 4.5 × 10 16  m −3 . After the EUV pulse the density slightly increases due to electron impact ionization. The plasma (i.e. electron density) decays in tens of microseconds. (fast track communication)

  2. Modification of some properties of polyamide-6 by electron beam induced grafting

    International Nuclear Information System (INIS)

    Timus, D.M.; Cincu, C.; Bradley, D.A.; Craciun, G.; Mateescu, E.

    2000-01-01

    Electron irradiation, applied on its own or in combination with other physical and chemical treatments, can result in radiation damage to materials. One category of such pursuits is electron beam radiation processing technologies, the intent being to produce favourable modification of materials. Study has been made herein of the use of accelerator-generated electron beams for the induced grafting of acrylic and methacrylic acids and acrylamide onto polyamide-6, the latter being popularly used in the textiles industry. Samples of polyamide-6, in the form of rectangular sheets of dimension, 10 cm x 10 cm or granules, have been irradiated using a 3 GHz travelling wave electron accelerator of energy 6.5 MeV. Results show that the degree of grafting is dependent upon radiation dose and extent of monomers dilution. Modifications have been observed in the melting temperature of the crystalline phase, glass transition temperature, mechanical parameters and the reticulation of polyamide

  3. Observation of thermal quench induced by runaway electrons in magnetic perturbation

    Science.gov (United States)

    Cheon, MunSeong; Seo, Dongcheol; Kim, Junghee

    2018-04-01

    Experimental observations in Korea Superconducting Tokamak Advanced Research (KSTAR) plasmas show that a loss of pre-disruptive runaway electrons can induce a rapid radiative cooling of the plasma, by generating impurity clouds from the first wall. The synchrotron radiation image shows that the loss of runaway electrons occurs from the edge region when the resonant magnetic perturbation is applied on the plasma. When the impact of the runaway electrons on the wall is strong enough, a sudden drop of the electron cyclotron emission (ECE) signal occurs with the characteristic plasma behaviors such as the positive spike and following decay of the plasma current, Dα spike, big magnetic fluctuation, etc. The visible images at this runaway loss show an evidence of the generation of impurity cloud and the following radiative cooling. When the runaway beam is located on the plasma edge, thermal quenches are expected to occur without global destruction of the magnetic structure up to the core.

  4. Wave-induced loss of ultra-relativistic electrons in the Van Allen radiation belts.

    Science.gov (United States)

    Shprits, Yuri Y; Drozdov, Alexander Y; Spasojevic, Maria; Kellerman, Adam C; Usanova, Maria E; Engebretson, Mark J; Agapitov, Oleksiy V; Zhelavskaya, Irina S; Raita, Tero J; Spence, Harlan E; Baker, Daniel N; Zhu, Hui; Aseev, Nikita A

    2016-09-28

    The dipole configuration of the Earth's magnetic field allows for the trapping of highly energetic particles, which form the radiation belts. Although significant advances have been made in understanding the acceleration mechanisms in the radiation belts, the loss processes remain poorly understood. Unique observations on 17 January 2013 provide detailed information throughout the belts on the energy spectrum and pitch angle (angle between the velocity of a particle and the magnetic field) distribution of electrons up to ultra-relativistic energies. Here we show that although relativistic electrons are enhanced, ultra-relativistic electrons become depleted and distributions of particles show very clear telltale signatures of electromagnetic ion cyclotron wave-induced loss. Comparisons between observations and modelling of the evolution of the electron flux and pitch angle show that electromagnetic ion cyclotron waves provide the dominant loss mechanism at ultra-relativistic energies and produce a profound dropout of the ultra-relativistic radiation belt fluxes.

  5. The Measurement of Electron-Induced Erosion of Condensed Gases: Experimental Methods

    DEFF Research Database (Denmark)

    Schou, Jørgen; Sørensen, H.; Børgesen, P.

    1984-01-01

    Two experimental methods for measuring the erosion yield of condensed gases are described. One, the frequency-change method, utilizes a quartz-crystal microbalance operating at liquid-helium temperature. The other, the emissivity-change method is based on the strongly varying electron emission...... as a function of the condensed-gas film thickness. Satisfactory results have been obtained for both methods for solid Ne and D2 at electron energies up to 3 keV, and the mutual agreement is good as well. Accurate measurements are affected critically by the beam conditions, particularly if the erosion yield...... depends on the film thickness. The erosion yield has been measured for dominant electron sputtering of solid Ne ( ≈ 28 Ne-atoms/electron) as well as for beam-induced evaporation at 2 keV. In the latter case a clear lateral broadening of the erosion spot is observed....

  6. The role of electron induced secondary electron emission from SiO2 surfaces in capacitively coupled radio frequency plasmas operated at low pressures

    Science.gov (United States)

    Horváth, B.; Daksha, M.; Korolov, I.; Derzsi, A.; Schulze, J.

    2017-12-01

    The effects of electron induced secondary electron (SE) emission from SiO2 electrodes in single-frequency capacitively coupled plasmas (CCPs) are studied by particle-in-cell/Monte Carlo collisions (PIC/MCC) simulations in argon gas at 0.5 Pa for different voltage amplitudes. Unlike conventional simulations, we use a realistic model for the description of electron-surface interactions, which takes into account the elastic reflection and the inelastic backscattering of electrons, as well as the emission of electron induced SEs (δ-electrons). The emission coefficients corresponding to these elementary processes are determined as a function of the electron energy and angle of incidence, taking the properties of the surface into account. Compared to the results obtained by using a simplified model for the electron-surface interaction, widely used in PIC/MCC simulations of CCPs, which includes only elastic electron reflection at a constant probability of 0.2, strongly different electron power absorption and ionization dynamics are observed. We find that ion induced SEs (γ-electrons) emitted at one electrode and accelerated to high energies by the local sheath electric field propagate through the plasma almost collisionlessly and impinge on the opposing sheath within a few nanoseconds. Depending on the instantaneous local sheath voltage these energetic electrons are either reflected by the sheath electric field or they hit the electrode surface, where each γ-electron can generate multiple δ-electrons upon impact. These electron induced SEs are accelerated back into the plasma by the momentary sheath electric field and can again generate δ-electrons at the opposite electrode after propagating through the plasma bulk. Overall, a complex dynamics of γ- and δ-electrons is observed including multiple reflections between the boundary sheaths. At high voltages, the electron induced SE emission is found to strongly affect the plasma density and the ionization dynamics and

  7. Low-energy electron diffraction and induced damage in hydrated DNA

    International Nuclear Information System (INIS)

    Orlando, Thomas M.; Oh, Doogie; Chen Yanfeng; Aleksandrov, Alexandr B.

    2008-01-01

    Elastic scattering of 5-30 eV electrons within the B-DNA 5 ' -CCGGCGCCGG-3 ' and A-DNA 5 ' -CGCGAATTCGCG-3 ' DNA sequences is calculated using the separable representation of a free-space electron propagator and a curved wave multiple scattering formalism. The disorder brought about by the surrounding water and helical base stacking leads to a featureless amplitude buildup of elastically scattered electrons on the sugar and phosphate groups for all energies between 5 and 30 eV. However, some constructive interference features arising from diffraction are revealed when examining the structural waters within the major groove. These appear at 5-10, 12-18, and 22-28 eV for the B-DNA target and at 7-11, 12-18, and 18-25 eV for the A-DNA target. Although the diffraction depends on the base-pair sequence, the energy dependent elastic scattering features are primarily associated with the structural water molecules localized within 8-10 A spheres surrounding the bases and/or the sugar-phosphate backbone. The electron density buildup occurs in energy regimes associated with dissociative electron attachment resonances, direct electronic excitation, and dissociative ionization. Since diffraction intensity can be localized on structural water, compound H 2 O:DNA states may contribute to energy dependent low-energy electron induced single and double strand breaks

  8. Low energy electron induced damage to plasmid DNA pQE30

    Science.gov (United States)

    Kumar, S. V. K.; Pota, Tasneem; Peri, Dinakar; Dongre, Anushka D.; Rao, Basuthkar J.

    2012-07-01

    Low energy electrons (LEEs) are produced in copious amounts by the primary radiation used in radiation therapy. The damage caused to the DNA by these secondary electrons in the energy range 5-22 eV has been studied to understand their possible role in radiation induced damage. Electrons are irradiated on dried films of plasmid DNA (pQE30) and analysed using agarose gel electrophoresis. Single strand breaks (SSBs) induced by LEE to supercoiled plasmid DNA show resonance structures at 7, 12, and 15 eV for low doses and 6, 10, and ˜18 eV at saturation doses. The present measurements have an overall agreement with the literature that LEEs resonantly induce SSBs in DNA. Resonant peaks in the SSBs induced by LEEs at 7, 12, and 15 eV with the lowest employed dose in the current study are somewhat different from those reported earlier by two groups. The observed differences are perhaps related to the irradiation dose, conditions and the nature of DNA employed, which is further elaborated.

  9. The fine structure of electron irradiation induced EL2-like defects in n-GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Tunhuma, S. M.; Auret, F. D.; Legodi, M. J.; Diale, M. [Department of Physics, University of Pretoria, Private Bag X20, Pretoria 0002 (South Africa)

    2016-04-14

    Defects induced by electron irradiation in n-GaAs have been studied using deep level transient spectroscopy (DLTS) and Laplace DLTS (L-DLTS). The E{sub 0.83} (EL2) is the only defect observed prior to irradiation. Ru/n-GaAs Schottky diodes were irradiated with high energy electrons from a Sr-90 radionuclide up to a fluence of 2.45 × 10{sup 13} cm{sup −2}. The prominent electron irradiation induced defects, E{sub 0.04}, E{sub 0.14}, E{sub 0.38}, and E{sub 0.63}, were observed together with the metastable E{sub 0.17}. Using L-DLTS, we observed the fine structure of a broad base EL2-like defect peak. This was found to be made up of the E{sub 0.75}, E{sub 0.83}, and E{sub 0.85} defects. Our study reveals that high energy electron irradiation increases the concentration of the E{sub 0.83} defect and introduces a family of defects with electronic properties similar to those of the EL2.

  10. e-Induced secondary electron emission yield of insulators and charging effects

    International Nuclear Information System (INIS)

    Cazaux, J.

    2006-01-01

    Based on a more realistic description of the in-depth secondary electron generation than that of standard (constant loss) model, a new model for the e-induced secondary electron emission yield, δ=f(E 0 ), is applied to account for the observed mean atomic number dependence of the reduced yield curves (RYC), δ/δ max =f(E 0 /E max 0 ) of a wide variety of inorganic insulators. It is next used to extract and to discuss physical information on secondary electron escape probability and attenuation length of a number of oxides and alkali halides and to deduce their X-ray-induced secondary electron emission yield, δ X =f(hν). Extrapolation of experimental data above the few keV energy range including the estimate of the nominal critical energy E 2 0 is also illustrated. Correlation between time dependence of charging and of secondary electron emission is next analyzed and various charging effects such as the observed negative charging when a positive charging was expected or the possible change of sign of the specimen current, are explained by the difference between E 2 0 and E 2 C (critical energy obtained under permanent irradiation). Strategies to identify charging effects via their influence on the distortion of the yield curve and to reduce them are finally suggested

  11. e-Induced secondary electron emission yield of insulators and charging effects

    Energy Technology Data Exchange (ETDEWEB)

    Cazaux, J. [LASSI/UTAP, Faculte des Sciences, Universite de Reims (DTI/CNRS), B.P. 1039, 51687 Reims Cedex 2 (France)]. E-mail: jacques.cazaux@univ-reims.fr

    2006-03-15

    Based on a more realistic description of the in-depth secondary electron generation than that of standard (constant loss) model, a new model for the e-induced secondary electron emission yield, {delta}=f(E{sup 0}), is applied to account for the observed mean atomic number dependence of the reduced yield curves (RYC), {delta}/{delta}{sub max}=f(E{sup 0}/E{sub max}{sup 0}) of a wide variety of inorganic insulators. It is next used to extract and to discuss physical information on secondary electron escape probability and attenuation length of a number of oxides and alkali halides and to deduce their X-ray-induced secondary electron emission yield, {delta}{sup X}=f(h{nu}). Extrapolation of experimental data above the few keV energy range including the estimate of the nominal critical energy E{sub 2}{sup 0} is also illustrated. Correlation between time dependence of charging and of secondary electron emission is next analyzed and various charging effects such as the observed negative charging when a positive charging was expected or the possible change of sign of the specimen current, are explained by the difference between E{sub 2}{sup 0} and E{sub 2}{sup C} (critical energy obtained under permanent irradiation). Strategies to identify charging effects via their influence on the distortion of the yield curve and to reduce them are finally suggested.

  12. Toward sensitive graphene nanoribbon-nanopore devices by preventing electron beam-induced damage.

    Science.gov (United States)

    Puster, Matthew; Rodríguez-Manzo, Julio A; Balan, Adrian; Drndić, Marija

    2013-12-23

    Graphene-based nanopore devices are promising candidates for next-generation DNA sequencing. Here we fabricated graphene nanoribbon-nanopore (GNR-NP) sensors for DNA detection. Nanopores with diameters in the range 2-10 nm were formed at the edge or in the center of graphene nanoribbons (GNRs), with widths between 20 and 250 nm and lengths of 600 nm, on 40 nm thick silicon nitride (SiN(x)) membranes. GNR conductance was monitored in situ during electron irradiation-induced nanopore formation inside a transmission electron microscope (TEM) operating at 200 kV. We show that GNR resistance increases linearly with electron dose and that GNR conductance and mobility decrease by a factor of 10 or more when GNRs are imaged at relatively high magnification with a broad beam prior to making a nanopore. By operating the TEM in scanning TEM (STEM) mode, in which the position of the converged electron beam can be controlled with high spatial precision via automated feedback, we were able to prevent electron beam-induced damage and make nanopores in highly conducting GNR sensors. This method minimizes the exposure of the GNRs to the beam before and during nanopore formation. The resulting GNRs with unchanged resistances after nanopore formation can sustain microampere currents at low voltages (∼50 mV) in buffered electrolyte solution and exhibit high sensitivity, with a large relative change of resistance upon changes of gate voltage, similar to pristine GNRs without nanopores.

  13. Geochronology, stratigraphy and geochemistry of Cambro-Ordovician, Silurian and Devonian volcanic rocks of the Saxothuringian Zone in NE Bavaria (Germany)—new constraints for Gondwana break up and ocean-island magmatism

    Science.gov (United States)

    Höhn, Stefan; Koglin, Nikola; Klopf, Lisa; Schüssler, Ulrich; Tragelehn, Harald; Frimmel, Hartwig E.; Zeh, Armin; Brätz, Helene

    2018-01-01

    Stratigraphically well-defined volcanic rocks in Palaeozoic volcano-sedimentary units of the Frankenwald area (Saxothuringian Zone, Variscan Orogen) were sampled for geochemical characterisation and U-Pb zircon dating. The oldest rock suite comprises quartz keratophyre, brecciated keratophyre, quartz keratophyre tuff and basalt, formed in Upper Cambrian to Tremadocian time (c. 497-478 Ma). Basaltic volcanism continued until the Silurian. Quartz keratophyre shows post-collisional calc-alkaline signature, the Ordovician-Silurian basalt has alkaline signature typical of continental rift environments. The combined datasets provide evidence of Cambro-Ordovician bimodal volcanism and successive rifting until the Silurian. This evolution very likely resulted from break-up of the northern Gondwana margin, as recorded in many terranes throughout Europe. The position at the northern Gondwana margin is supported by detrital zircon grains in some tuffs, with typical Gondwana-derived age spectra mostly recording ages of 550-750 Ma and minor age populations of 950-1100 and 1700-2700 Ma. The absence of N-MORB basalt in the Frankenwald area points to a retarded break-off of the Saxothuringian terrane along a continental rift system from Uppermost Cambrian to Middle Silurian time. Geochemical data for a second suite of Upper Devonian basalt provide evidence of emplacement in a hot spot-related ocean-island setting south of the Rheic Ocean. Our results also require partial revision of the lithostratigraphy of the Frankenwald area. The basal volcanic unit of the Randschiefer Formation yielded a Tremadocian age and, therefore, should be attributed to the Vogtendorf Formation. Keratophyre of the Vogtendorf Formation, previously assigned to the Tremadoc, is most likely of Upper Devonian age.

  14. Hot electron-induced electrogenerated chemiluminescence of SYBR[reg] Green I

    International Nuclear Information System (INIS)

    Laakso, Pirita; Anttila, Hannamari; Kairisto, Veli; Eskola, Jarkko; Kulmala, Sakari; Ala-Kleme, Timo

    2005-01-01

    Hot electrons can be injected from conductor/insulator/electrolyte (C/I/E) junctions into an aqueous electrolyte solution. Injected hot electrons induce electrogenerated chemiluminescence (ECL) of various luminophores in fully aqueous solutions. Such ECL gives the basis of electrochemiluminoimmunoassays and DNA-probe assays where different luminophores can be used as electrochemiluminescent labels. This work shows that SYBR[reg] Green I is suitable as an ECL label in detection methods based on C/I/E tunnel-emission electrodes such as oxide-coated aluminium, magnesium and silicon electrodes

  15. Radiation induced synthesis of gold/iron-oxide composite nanoparticles using high-energy electron beam

    International Nuclear Information System (INIS)

    Seino, Satoshi; Kinoshita, Takuya; Nakagawa, Takashi; Kojima, Takao; Taniguci, Ryoichi; Okuda, Shuichi; Yamamoto, Takao A.

    2008-01-01

    Composite nanoparticles consisting of gold and iron oxide were synthesized in aqueous solution systems by using a high-energy electron beam. The electron irradiation induces radiation-chemical reaction to form metallic gold nanoparticles. These gold nanoparticles were firmly immobilized on the surface of the support iron oxide nanoparticles. Surface of the support iron oxide nanoparticles are almost fully coated with fine gold nanoparticles. The size of these gold nanoparticles depended on the concentrations of gold ions, polymers and iron oxide nanoparticles in the solutions before the irradiation.

  16. Nascent stages of DNA radiolysis: secondary electron and reactive ion induced damage

    International Nuclear Information System (INIS)

    Huels, M.A.

    2000-01-01

    Full text: It is by now well understood that most of the energy deposited in solids by ionizing radiation is converted within less than attoseconds into the production of ions, radicals, and ballistic low-energy secondary electrons. The latter are known to decompose small molecules even at electron energies well below molecular ionization thresholds regardless of molecular aggregation state, and have recently been shown to induce substantial yields of single and double strand breaks in supercoiled DNA. In that study, we found that the electron-energy dependent strand break yields have a strong maximum near 10 eV, which was attributed to the decomposition of transient molecular anion (TMA) states, i.e. resonances. The localization of these resonances on the different components of DNA leads to dissociations into anion and radical fragments within femtoseconds, where subsequent fragment reactions on similar timescales are thought to lead to the final observed DNA damage. In order to unravel this sequence of secondary electron and reactive ion induced events, and to better understand their fundamental reaction pathways, we have performed, and will present: (a) measurements of the basic mechanisms by which low-energy (0-30 eV) electrons induce damage to different components of DNA, e.g. H 2 0, deoxyribose analogs, bases, as well as other organic model systems, and (b) measurements of the basic reaction pathways by which some of the energetic ion fragments observed in (a) induce further damage in simple hydrocarbon films, as well as solids of DNA components, or their structural analogs. Our experiments show that: (i) for electron energies below 15 eV dissociative electron attachment (i.e. resonances) results in exocyclic and complex endocyclic bond cleavages in any of the molecular systems studied, leading to the formation of a vast variety of reactive radical and anion fragments, whereas above 15 eV electronic excitations and ionizations (nonresonant mechanisms) may

  17. Electron kinetics dependence on gas pressure in laser-induced oxygen plasma experiment: Theoretical analysis

    Science.gov (United States)

    Gamal, Yosr E. E.-D.; Abdellatif, Galila

    2017-08-01

    A study is performed to investigate the dependency of threshold intensity on gas pressure observed in the measurements of the breakdown of molecular oxygen that carried out by Phuoc (2000) [1]. In this experiment, the breakdown was induced by 532 nm laser radiation of pulse width 5.5 ns and spot size of 8.5 μm, in oxygen over a wide pressure range (190-3000 Torr). The analysis aimed to explore the electron kinetic reliance on gas pressure for the separate contribution of each of the gain and loss processes encountered in this study. The investigation is based on an electron cascade model applied previously in Gamal and Omar (2001) [2] and Gaabour et al. (2013) [3]. This model solves numerically a differential equation designates the time evolution of the electron energy distribution, and a set of rate equations that describe the change of excited states population. The numerical examination of the electron energy distribution function and its parameters revealed that photo-ionization of the excited molecules plays a significant role in enhancing the electron density growth rate over the whole tested gas pressure range. This process is off set by diffusion of electrons out of the focal volume in the low-pressure regime. At atmospheric pressure electron, collisional processes dominate and act mainly to populate the excited states. Hence photo-ionization becomes efficient and compete with the encountered loss processes (electron diffusion, vibrational excitation of the ground state molecules as well as two body attachments). At high pressures ( 3000 Torr) three body attachments are found to be the primary cause of losses which deplete the electron density and hence results in the slow decrease of the threshold intensity.

  18. Electronic modification of Cu-based chalcopyrite semiconductors induced by lattice deformation and composition alchemy

    Science.gov (United States)

    Jiang, F. D.; Feng, J. Y.

    2008-02-01

    Using first principles calculation, we systematically investigate the electronic modification of Cu-based chalcopyrite semiconductors induced by lattice deformation and composition alchemy. It is shown that the optical band gap Eg is remarkably sensitive to the anion displacement μ, resulting from the opposite shifts of conduction band minimum and valence band maximum. Meanwhile, the dependence of structural parameters of alloyed compounds on alloy composition x is demonstrated for both cation and anion alloying. The d orbitals of group-III cations are found to be of great importance in the calculation. Abnormal changes in the optical band gap Eg induced by anion alloying are addressed.

  19. Electronic modification of Cu-based chalcopyrite semiconductors induced by lattice deformation and composition alchemy

    International Nuclear Information System (INIS)

    Jiang, F D; Feng, J Y

    2008-01-01

    Using first principles calculation, we systematically investigate the electronic modification of Cu-based chalcopyrite semiconductors induced by lattice deformation and composition alchemy. It is shown that the optical band gap E g is remarkably sensitive to the anion displacement μ, resulting from the opposite shifts of conduction band minimum and valence band maximum. Meanwhile, the dependence of structural parameters of alloyed compounds on alloy composition x is demonstrated for both cation and anion alloying. The d orbitals of group-III cations are found to be of great importance in the calculation. Abnormal changes in the optical band gap E g induced by anion alloying are addressed

  20. Laser-Induced Skyrmion Writing and Erasing in an Ultrafast Cryo-Lorentz Transmission Electron Microscope

    Science.gov (United States)

    Berruto, G.; Madan, I.; Murooka, Y.; Vanacore, G. M.; Pomarico, E.; Rajeswari, J.; Lamb, R.; Huang, P.; Kruchkov, A. J.; Togawa, Y.; LaGrange, T.; McGrouther, D.; Rønnow, H. M.; Carbone, F.

    2018-03-01

    We demonstrate that light-induced heat pulses of different duration and energy can write Skyrmions in a broad range of temperatures and magnetic field in FeGe. Using a combination of camera-rate and pump-probe cryo-Lorentz transmission electron microscopy, we directly resolve the spatiotemporal evolution of the magnetization ensuing optical excitation. The Skyrmion lattice was found to maintain its structural properties during the laser-induced demagnetization, and its recovery to the initial state happened in the sub-μ s to μ s range, depending on the cooling rate of the system.

  1. Preliminary examination of induced radioactivity in pepper by 10 MeV electron irradiation

    International Nuclear Information System (INIS)

    Katayama, Tadashi; Furuta, Masakazu; Sibata, Setsuko; Ito, Norio; Mizohata, Akira; Matsunami, Tadao; Toratani, Hirokazu; Takeda, Atsuhiko.

    1991-01-01

    β-ray measurement was performed on 10 MeV electron-irradiated black pepper and white pepper with liquid scintillation counter in order to reconfirm the wholesomeness of irradiated foods and present unambiguous data to general consumers concerning about the induced radioactivity in the irradiated foods. In irradiated black pepper no radioactivity other than from natural source, un-irradiated one, was detected. But in irradiated white pepper, it was suggested that induced radioactivity might be detected if the detection method was more improved. (author)

  2. Surface chemical reactions induced by molecules electronically-excited in the gas

    DEFF Research Database (Denmark)

    Petrunin, Victor V.

    2011-01-01

    and alignment are taking place, guiding all the molecules towards the intersections with the ground state PES, where transitions to the ground state PES will occur with minimum energy dissipation. The accumulated kinetic energy may be used to overcome the chemical reaction barrier. While recombination chemical...... beams inducing the reaction can be used to distinguish the new process we try to investigate from chemical reactions induced by photoexcitation within adsorbed molecules and/or gas phase photolysis.......We present a model suggesting high chemical activity of electronically-excited molecules colliding with an isolator surface. Initial photochemical event is accounted for as the result of molecular evolution on the electronically-excited potential energy surface (PES), where acceleration...

  3. Evaluation of induced radioactivity in 10 MeV-Electron irradiated spices, (2)

    International Nuclear Information System (INIS)

    Katayama, Tadashi; Furuta, Masakazu; Shibata, Setsuko; Matsunami, Tadao; Ito, Norio; Mizohata, Akira; Toratani, Hirokazu; Takeda, Atsuhiko.

    1994-01-01

    In order to check radioactivity of beta-emmitters produced by (γ, n) reactions which could occur at energies up to 10 MeV, black pepper, white pepper, red pepper, ginger and turmeric were irradiated with 10 MeV electron from a linear accelerator to a dose of 100 kGy. Beta-rays were counted using a 2π gas flow counter and a liquid scintillation counter. Any induced radioactivity could not be detected in irradiated samples. When inorganic compounds containing the nuclides in the list were artificially added in the samples and were irradiated, the β-activities were detected. From the amount of observed radioactivities of β-emmitters produced in the compounds as photonuclear products, it is concluded that the induced radioactivity in natural samples by 10 MeV-electron irradiation were far smaller than natural radioactivity from 40 K contained in the samples and, hence, its biological effects should be negligible. (author)

  4. Electron irradiation induced buckling, morphological transformation, and inverse Ostwald ripening in nanorod filled inside carbon nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anshika; Kumari, Reetu; Kumar, Vinay; Krishnia, Lucky; Naqvi, Zainab; Panwar, Amrish K. [Department of Applied Physics, Delhi Technological University, Delhi, 110042 (India); Bhatta, Umananda M. [Centre for Emerging Technologies, Jain University, Jakkasandra, Kanakapura Taluk, Ramanagaram Dist, Karnataka, PIN 562 112 (India); Ghosh, Arnab; Satyam, P.V. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Tyagi, Pawan K., E-mail: pawantyagi@dce.edu [Department of Applied Physics, Delhi Technological University, Delhi, 110042 (India)

    2016-01-01

    Graphical abstract: - Highlights: • In-situ response of iron carbide (Fe{sub 3}C) nanorod filled inside carbon nanotube (CNT) under electron irradiation has been studied at room and high temperature. • Inverse Ostwald ripening and morphological changes in both carbon nanotube as well as nanorod are observed. • Compression generated either by electron beam heating or by shrinkage of CNT walls has been observed to be a decisive factor. • Temperature during the irradiation shows high impact on irradiation induced changes. - Abstract: The present study aims to deduce the in-situ response of iron carbide (Fe{sub 3}C) nanorod filled inside carbon nanotube (CNT) under electron irradiation. Electron irradiation on Fe{sub 3}C filled-CNT at both high and room temperature (RT) has been performed inside transmission electron microscope. At high temperature (HT), it has been found that γ-Fe atoms in lattice of Fe{sub 3}C nanorod accumulate first and then form the cluster. These clusters follow the inverse Ostwald ripening whereas if e-irradiation is performed at RT then only the morphological changes in both carbon nanotube as well as nanorod are observed. Compression generated either by electron beam heating or by shrinkage of CNT walls is observed to be a decisive factor.

  5. Electron spectroscopic study of electronic and morphological modifications of the WSe2 surface induced by Rb adsorption

    International Nuclear Information System (INIS)

    Buck, Jens

    2010-01-01

    The rubidium-covered surface of the semiconducting transition metal dichalcogenide tungsten diselenide (WSe 2 ) is examined using photoelectron spectroscopy (PES) and photoemission electron microscopy (PEEM). Adsorbed Rb is known to induce a variety of effects in this system concerning electronic, structural, and mechanical properties. In this work, the surface potential created by charge transfer upon Rb deposition is examined in thermal equilibrium (band bending) and stationary non-equilibrium (surface photovoltage (SPV) effect), which is induced by the absorption of light. It is shown that combined measurements and numerical simulations of the SPV effect as a function of the photon flux can be exploited for the estimation of many material parameters of the system, especially of the unoccupied adsorbate state. Issues of extending a conventional photoelectron spectrometer setup by a secondary light source will be discussed in the context of simulations and calibration measurements. The customization of an existing theoretical model of the SPV effect for the WSe 2 : Rb system is introduced, and a comprehensive validation of the obtained predictions is given in the context of experimental data. In addition, the self-organized formation of Rb domains at room temperature was examined by application of spatially resolved XPS spectroscopy using the PEEM setup at the end station of beamline UE49/PGMa at the BESSY II synchrotron facility. From the obtained results, the arrangement of Rb in surface lattices can be concluded. Furthermore, an X-Ray absorption study of self-organized nanostructure networks, aiming at the chemical characterization, is presented. Based on the interpretation of the examined structures as tension-induced cracks, a statistical approach to analyzing large-scale features was pursued. First accordance with the predictions made by a primitive, mechanical model of crack creation developed here gives gives some evidence for the validity of the proposed

  6. Electron spectroscopic study of electronic and morphological modifications of the WSe{sub 2} surface induced by Rb adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Buck, Jens

    2010-07-20

    The rubidium-covered surface of the semiconducting transition metal dichalcogenide tungsten diselenide (WSe{sub 2}) is examined using photoelectron spectroscopy (PES) and photoemission electron microscopy (PEEM). Adsorbed Rb is known to induce a variety of effects in this system concerning electronic, structural, and mechanical properties. In this work, the surface potential created by charge transfer upon Rb deposition is examined in thermal equilibrium (band bending) and stationary non-equilibrium (surface photovoltage (SPV) effect), which is induced by the absorption of light. It is shown that combined measurements and numerical simulations of the SPV effect as a function of the photon flux can be exploited for the estimation of many material parameters of the system, especially of the unoccupied adsorbate state. Issues of extending a conventional photoelectron spectrometer setup by a secondary light source will be discussed in the context of simulations and calibration measurements. The customization of an existing theoretical model of the SPV effect for the WSe{sub 2}: Rb system is introduced, and a comprehensive validation of the obtained predictions is given in the context of experimental data. In addition, the self-organized formation of Rb domains at room temperature was examined by application of spatially resolved XPS spectroscopy using the PEEM setup at the end station of beamline UE49/PGMa at the BESSY II synchrotron facility. From the obtained results, the arrangement of Rb in surface lattices can be concluded. Furthermore, an X-Ray absorption study of self-organized nanostructure networks, aiming at the chemical characterization, is presented. Based on the interpretation of the examined structures as tension-induced cracks, a statistical approach to analyzing large-scale features was pursued. First accordance with the predictions made by a primitive, mechanical model of crack creation developed here gives gives some evidence for the validity of the

  7. Defect production and subsequent effects induced by electronic energy loss of swift heavy ion

    International Nuclear Information System (INIS)

    Hou Mingdong; Liu Jie; Sun Youmei; Yin Jingmin; Yao Huijun; Duan Jinglai; Mo Dan; Zhang Ling; Chen Yanfeng; Chinese Academy of Sciences, Beijing

    2008-01-01

    Swift heavy ion in matter is one of forfront fields of nuclear physics in the world. A series of new phenomena were discovered in recent years. The history and sta- tus on the development of this field were reviewed. Electronic energy loss effects induced by swift heavy ion irradiation, such as defect production and evolution, ion latent track formation, phase transformation and anisotropy plastic deformation were introduced emphatically. A trend of future investigation was explored. (authors)

  8. Heat-induced antigen retrieval of epoxy sections for electron microscopy

    OpenAIRE

    Brorson, S.H.

    2001-01-01

    The purpose of this manuscript is to review the literature on the use of heat-induced antigen retrieval methods to enhance the immunolabeling of epoxy sections at the electron microscopical level. The history of the development of antigen retrieval by heating formaldehyde fixed paraffin sections in a buffer solution is given in short, and how this technique has been extended to resin sections and in particular epoxy sections is explained. Theories for the mecha...

  9. Electron yield from Be-Cu induced by highly charged Xe q+ ions

    Czech Academy of Sciences Publication Activity Database

    Krása, Josef; Láska, Leoš; Stöckli, M. P.; Fehrenbach, C. W.

    2002-01-01

    Roč. 196, - (2002), s. 61-67 ISSN 0168-583X R&D Projects: GA AV ČR IAA1010105; GA MŠk LN00A100 Institutional research plan: CEZ:AV0Z1010921 Keywords : highly charged ion-induced electron emission * angle impact effect * Be-Cu Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.158, year: 2002

  10. Interaction-induced huge magnetoresistance in a high mobility two-dimensional electron gas

    Energy Technology Data Exchange (ETDEWEB)

    Bockhorn, L.; Haug, R. J. [Institut für Festkörperphysik, Leibniz Universität Hannover, D-30167 Hannover (Germany); Gornyi, I. V. [Institut für Nanotechnologie, Karlsruher Institut of Technology, D-76021 Karlsruhe (Germany); Schuh, D. [Institut für Experimentelle und Angewandte Physik, Universität Regensburg, D-93053 Regensburg (Germany); Wegscheider, W. [ETH Zürich (Switzerland)

    2013-12-04

    A strong negative magnetoresistance is observed in a high-mobility two-dimensional electron gas in a GaAs/Al{sub 0.3}Ga{sub 0.7}As quantum well. We discuss that the negative magnetoresistance consists of a small peak induced by a combination of two types of disorder and a huge magnetoresistance explained by the interaction correction to the conductivity for mixed disorder.

  11. Selected immobilization of individual nanoparticles by spot-exposure electron-beam-induced deposition

    Energy Technology Data Exchange (ETDEWEB)

    Burbridge, Daniel J; Crampin, Simon; Gordeev, Sergey N [Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Viau, Guillaume [Departement de Genie Physique, INSA de Toulouse, 135 avenue de Rangueil, 31077 Toulouse Cedex 4 (France)

    2010-01-29

    The use of spot-exposure electron-beam-induced deposition (EBID) to immobilize targeted nanoparticles on a substrate is demonstrated, and investigated using experiment and simulation. Nanoparticles are secured in place through the build-up of carbonaceous material that forms in the region between a particle and substrate when an energetic electron beam is focused onto the particle and projected through to the substrate. Material build-up directly affects the strength of adhesion to the surface, and can be controlled through electron dosage and beam energy. By selectively immobilizing specific particles within surface agglomerations and removing the excess, we illustrate the potential for spot-exposure EBID as a new technique for nanofabrication.

  12. Effect of storage conditions on graft of polypropylene non-woven fabric induced by electron beam

    International Nuclear Information System (INIS)

    Lee, Jin Young; Jeun, Joon Pyo; Kang, Phil Hyun

    2015-01-01

    In this study, we fabricated effect of storage conditions on graft of polypropylene (PP) non-woven fabric induced by electron beam. The electron beam irradiations on PP non-woven fabric were carried out over a range of irradiation doses from 25 to 100 kGy to make free radicals on fabric surface. The radical measurement was established by electron spin resonance (ESR) for confirming the changes of the alkyl radical and peroxy radical according to effect of storage time, storage temperature and atmosphere. It was observed that the free radicals were increased with irradiation dose and decreased with storage time due to the continuous oxidation. However, the radical extinction was significantly delayed due to reduced mobility of radicals at extremely low temperature. The degree of graft based on the analysis of ESR was investigated. The conditions of graft reaction were set at a temperature: 60 degrees Celcius, reaction time: 6 hours and styrene monomer concentration: 20 wt%

  13. How does methylation suppress the electron-induced decomposition of 1-methyl-nitroimidazoles?

    Science.gov (United States)

    Kossoski, F.; Varella, M. T. do N.

    2017-10-01

    The efficient decomposition of nitroimidazoles (NIs) by low energy electrons is believed to underlie their radiosensitizing properties. Recent dissociative electron attachment (DEA) measurements showed that methylation at the N1 site unexpectedly suppresses the electron-induced reactions in 4(5)-NI. We report theoretical results that provide a clear interpretation of that astounding finding. Around 1.5 eV, DEA reactions into several fragments are initiated by a π* resonance, not considered in previous studies. The autoionization lifetime of this anion state, which limits the predissociation dynamics, is considerably shorter in the methylated species, thereby suppressing the DEA signals. On the other hand, the lifetime of the π* resonance located around 3 eV is less affected by methylation, which explains why DEA is still observed at these energies. Our results demonstrate how even a simple methylation can significantly modify the probabilities for DEA reactions, which may be significant for NI-based cancer therapy.

  14. Standard Practice for Ensuring Test Consistency in Neutron-Induced Displacement Damage of Electronic Parts

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This practice sets forth requirements to ensure consistency in neutron-induced displacement damage testing of silicon and gallium arsenide electronic piece parts. This requires controls on facility, dosimetry, tester, and communications processes that affect the accuracy and reproducibility of these tests. It provides background information on the technical basis for the requirements and additional recommendations on neutron testing. In addition to neutrons, reactors are used to provide gamma-ray pulses of intensities and durations that are not achievable elsewhere. This practice also provides background information and recommendations on gamma-ray testing of electronics using nuclear reactors. 1.2 Methods are presented for ensuring and validating consistency in neutron displacement damage testing of electronic parts such as integrated circuits, transistors, and diodes. The issues identified and the controls set forth in this practice address the characterization and suitability of the radiation environm...

  15. Effect of storage conditions on graft of polypropylene non-woven fabric induced by electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin Young; Jeun, Joon Pyo; Kang, Phil Hyun [Radiation Research Dvision for Industry and Environment, Korea Atomic Energy Research Institute, Jeongeup(Korea, Republic of)

    2015-05-15

    In this study, we fabricated effect of storage conditions on graft of polypropylene (PP) non-woven fabric induced by electron beam. The electron beam irradiations on PP non-woven fabric were carried out over a range of irradiation doses from 25 to 100 kGy to make free radicals on fabric surface. The radical measurement was established by electron spin resonance (ESR) for confirming the changes of the alkyl radical and peroxy radical according to effect of storage time, storage temperature and atmosphere. It was observed that the free radicals were increased with irradiation dose and decreased with storage time due to the continuous oxidation. However, the radical extinction was significantly delayed due to reduced mobility of radicals at extremely low temperature. The degree of graft based on the analysis of ESR was investigated. The conditions of graft reaction were set at a temperature: 60 degrees Celcius, reaction time: 6 hours and styrene monomer concentration: 20 wt%.

  16. Visible-light-induced two-electron-transfer photoreductions on CdS: Effects of morphology

    Energy Technology Data Exchange (ETDEWEB)

    Shiragami, Tsutomu; Pac, Chyongjin; Yanagida, Shozo (Osaka Univ. (Japan))

    1990-01-25

    Freshly prepared CdS suspensions (CdS-O) consisting of quantized particles and their loose aggregation catalyze photoreductions of aromatic ketones and olefins in methanol under visible light irradiation using triethylamine as sacrificial electron donor, yielding alcohols and dihydro compounds, respectively, which are more selective than photocatalysis of commercially available crystalline CdS (Aldrich) (CdS-Ald). Deuterium incorporation experiments in photolysis of dimethyl maleate in methanol-O-D revealed that CdS-O catalyzes sequential two-electron-transfer photoreduction, affording dideuterated dimethyl succinate, while CdS-Ald induces both photoreduction and photoisomerization through disproportionation between one-electron-transfer-reduction intermediates, yielding much trideuterated dimethyl succinate and monodeuterated dimethyl fumarate and maleate.

  17. Observation of whispering gallery modes through electron beam-induced deposition.

    Science.gov (United States)

    Timmermans, F J; Chang, L; van Wolferen, H A G M; Lenferink, A T M; Otto, C

    2017-04-01

    Surprisingly intense spectra of whispering gallery modes were observed in polymer microbeads after illumination with electrons in a scanning electron microscope and subsequent laser illumination and spectral analysis. It will be proposed that whispering gallery mode resonances became visible after local deposition of hydrocarbon material through electron beam-induced deposition. The illumination of deposited material with a near infrared laser generates a broad light spectrum, acting as a local "white light" source that couples, for favorable wavelengths, with the WGM sustained by the sphere. This facilitates a spectroscopic analysis of the WGM and provides the Q-factor and free spectral range for all investigated particles. The analysis by an integrated SEM and Raman micro-spectrometer offers a direct approach to the analysis of WGM resonators as they are, for instance, used in sensing.

  18. Induced superconductivity in high-mobility two-dimensional electron gas in gallium arsenide heterostructures.

    Science.gov (United States)

    Wan, Zhong; Kazakov, Aleksandr; Manfra, Michael J; Pfeiffer, Loren N; West, Ken W; Rokhinson, Leonid P

    2015-06-11

    Search for Majorana fermions renewed interest in semiconductor-superconductor interfaces, while a quest for higher-order non-Abelian excitations demands formation of superconducting contacts to materials with fractionalized excitations, such as a two-dimensional electron gas in a fractional quantum Hall regime. Here we report induced superconductivity in high-mobility two-dimensional electron gas in gallium arsenide heterostructures and development of highly transparent semiconductor-superconductor ohmic contacts. Supercurrent with characteristic temperature dependence of a ballistic junction has been observed across 0.6 μm, a regime previously achieved only in point contacts but essential to the formation of well separated non-Abelian states. High critical fields (>16 T) in NbN contacts enables investigation of an interplay between superconductivity and strongly correlated states in a two-dimensional electron gas at high magnetic fields.

  19. Degradation kinetics of poly(ether-urethane) Estane[reg] induced by electron irradiation

    International Nuclear Information System (INIS)

    Dannoux, A.; Esnouf, S.; Begue, J.; Amekraz, B.; Moulin, C.

    2005-01-01

    Radiation effects on a segmented aromatic poly(ether-urethane) induced by electron beam irradiation under oxygen atmosphere were investigated using Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance (EPR) in order to determine the degradation mechanisms. Thin films have been irradiated under a dose rate of 1 MGy/h with absorbed doses varying from 25 to 1000 kGy under O 2 . FTIR spectra have shown the formation of hydroperoxides, carboxylic acids, primary amines, alcohols, esters and formates. Moreover, the decrease of urethane and ether absorbances revealed the degradation of both soft and hard segments. Spin-trapping technique was used to monitor the evolution of short-lived peroxy and alkyl radicals at room temperature. Finally, a mechanism of degradation for electron irradiated polyurethane is proposed

  20. Nonlinear Dynamics of Fast-electron Driven Beta-induced Alfven eigenmode

    Science.gov (United States)

    Cheng, Junyi; Zhang, Wenlu; Lin, Zhihong; Li, Ding

    2017-10-01

    The fast-electron driven beta-induced Alfven eigenmode (e-BAE) has been routinely observed in HL-2A tokamak. We study e-BAE for the first time using global gyrokinetic GTC simulations, where the fast electrons are described by the drift kinetic model. Frequency chirping is observed in nonlinear simulations in the absence of sources and sinks, which provides a new nonlinear paradigm beyond the standard ``bump-on-tail'' model. Analysis of nonlinear wave-particle interactions shows that the frequency chirping is induced by the nonlinear evolution of the coherent structures in the fast electron phase space, where the dynamics of the coherent structure is controlled by the formation and destruction of phase space islands in the canonical variables. Furthermore, we put forward a new theory frame to demonstrate that the evolution of chirping phenomenon is essentially induced by balance and destruction of net shear flow in the toroidal direction combined by the background shear flow and perturbed shear flow, which provides a novel and clear physical image.

  1. Electron-induced dry reforming of methane in a temperature-controlled dielectric barrier discharge reactor

    KAUST Repository

    Zhang, Xuming

    2013-09-23

    Dry reforming of methane has the potential to reduce the greenhouse gases methane and carbon dioxide and to generate hydrogen-rich syngas. In reforming methane, plasma-assisted reforming processes may have advantages over catalytic processes because they are free from coking and their response time for mobile applications is quick. Although plasma-assisted reforming techniques have seen recent developments, systematic studies that clarify the roles that electron-induced chemistry and thermo-chemistry play are needed for a full understanding of the mechanisms of plasma-assisted reformation. Here, we developed a temperature-controlled coaxial dielectric barrier discharge (DBD) apparatus to investigate the relative importance of electron-induced chemistry and thermo-chemistry in dry reforming of methane. In the tested background temperature range 297-773 K, electron-induced chemistry, as characterized by the physical properties of micro-discharges, was found to govern the conversions of CH4 and CO2, while thermo-chemistry influenced the product selectivities because they were found to depend on the background temperature. Comparisons with results from arc-jet reformation indicated that thermo-chemistry is an efficient conversion method. Our findings may improve designs of plasma-assisted reformers by using relatively hotter plasma sources. However, detailed chemical kinetic studies are needed. © 2013 IOP Publishing Ltd.

  2. Electronic excitation induced modifications in elongated iron nanoparticle encapsulated multiwalled carbon nanotubes under ion irradiation

    Science.gov (United States)

    Saikiran, V.; Bazylewski, P.; Sameera, I.; Bhatia, Ravi; Pathak, A. P.; Prasad, V.; Chang, G. S.

    2018-05-01

    Multi-wall carbon nanotubes (MWCNT) filled with Fe nanorods were shown to have contracted and deformed under heavy ion irradiation. In this study, 120 MeV Ag and 80 MeV Ni ion irradiation was performed to study the deformation and defects induced in iron filled MWCNT under heavy ion irradiation. The structural modifications induced due to electronic excitation by ion irradiation were investigated employing high-resolution transmission electron microscopy, micro-Raman scattering experiments, and synchrotron-based X-ray absorption and emission spectroscopy. We understand that the ion irradiation causes modifications in the Fe nanorods which result in compressions and expansions of the nanotubes, and in turn leads to the buckling of MWCNT. The G band of the Raman spectra shifts slightly towards higher wavenumber and the shoulder G‧ band enhances with the increase of ion irradiation fluence, where the buckling wavelength depends on the radius 'r' of the nanotubes as exp[(r)0.5]. The intensity ratio of the D to G Raman modes initially decreases at the lowest fluence, and then it increases with the increase in ion fluence. The electron diffraction pattern and the high resolution images clearly show the presence of ion induced defects on the walls of the tube and encapsulated iron nanorods.

  3. Biguanides sensitize leukemia cells to ABT-737-induced apoptosis by inhibiting mitochondrial electron transport

    Science.gov (United States)

    Velez, Juliana; Pan, Rongqing; Lee, Jason T.C.; Enciso, Leonardo; Suarez, Marta; Duque, Jorge Eduardo; Jaramillo, Daniel; Lopez, Catalina; Morales, Ludis; Bornmann, William; Konopleva, Marina; Krystal, Gerald; Andreeff, Michael; Samudio, Ismael

    2016-01-01

    Metformin displays antileukemic effects partly due to activation of AMPK and subsequent inhibition of mTOR signaling. Nevertheless, Metformin also inhibits mitochondrial electron transport at complex I in an AMPK-independent manner, Here we report that Metformin and rotenone inhibit mitochondrial electron transport and increase triglyceride levels in leukemia cell lines, suggesting impairment of fatty acid oxidation (FAO). We also report that, like other FAO inhibitors, both agents and the related biguanide, Phenformin, increase sensitivity to apoptosis induction by the bcl-2 inhibitor ABT-737 supporting the notion that electron transport antagonizes activation of the intrinsic apoptosis pathway in leukemia cells. Both biguanides and rotenone induce superoxide generation in leukemia cells, indicating that oxidative damage may sensitize toABT-737 induced apoptosis. In addition, we demonstrate that Metformin sensitizes leukemia cells to the oligomerization of Bak, suggesting that the observed synergy with ABT-737 is mediated, at least in part, by enhanced outer mitochondrial membrane permeabilization. Notably, Phenformin was at least 10-fold more potent than Metformin in abrogating electron transport and increasing sensitivity to ABT-737, suggesting that this agent may be better suited for targeting hematological malignancies. Taken together, our results suggest that inhibition of mitochondrial metabolism by Metformin or Phenformin is associated with increased leukemia cell susceptibility to induction of intrinsic apoptosis, and provide a rationale for clinical studies exploring the efficacy of combining biguanides with the orally bioavailable derivative of ABT-737, Venetoclax. PMID:27283492

  4. Electron beam induced Hg desorption and the electronic structure of the Hg depleted surface of Hg1/sub -//sub x/Cd/sub x/Te

    International Nuclear Information System (INIS)

    Shih, C.K.; Friedman, D.J.; Bertness, K.A.; Lindau, I.; Spicer, W.E.; Wilson, J.A.

    1986-01-01

    Auger electron spectroscopy (AES), x-ray photoemission spectroscopy (XPS), low energy electron diffraction (LEED), and angle-resolved ultraviolet photoemission spectroscopy (ARPES) were used to study the electron beam induced Hg desorption from a cleaved (110)Hg/sub 1-//sub x/Cd/sub x/Te surface and the electronic structure of the Hg depleted surface. Solid state recrystallized Hg/sub 1-//sub x/Cd/sub x/Te single crystals were used. It was found that the electron beam heating dominated the electron beam induced Hg desorption on Hg/sub 1-//sub x/Cd/sub x/Te. At the electron beam energy used, the electron beam heating extended several thousand angstroms deep. However, the Hg depletion saturated after a few monolayers were depleted of Hg atoms. At the initial stage of Hg loss (only 3%), the surface band bends upward (more p type). The ARPES spectrum showed the loss of some E vs k dispersion after 22% Hg atoms were removed from the surface region, and no dispersion was observed after 43% Hg atoms were removed. These results have important implications on the electronic structure of the surfaces and interfaces of which the stoichiometry is altered

  5. Progress in studies of Electron-Cloud-Induced Optics Distortions at CESRTA

    International Nuclear Information System (INIS)

    Crittenden, J.A.; Calvey, J.R.; Dugan, G.F.; Kreinick, D.L.; Leong, Z.; Livezey, J.A.; Palmer, M.A.; Rubin, D.L.; Sagan, D.C.; Holtzapple, R.L.; Furman, M.A.; Penn, G.; Venturini, M.; Pivi, M.; Wang, L.; Harkay, K.

    2010-01-01

    The Cornell Electron Storage Ring Test Accelerator (CesrTA) program has included extensive measurements of coherent betatron tune shifts for a variety of electron and positron beam energies, bunch population levels, and bunch train configurations. The tune shifts have been shown to result primarily from the interaction of the beam with the space-charge field of the beam-induced low energy electron cloud in the vacuum chamber. Comparison to several advanced electron cloud simulation program packages has allowed determination of the sensitivity of these measurements to physical parameters characterizing the synchrotron radiation flux, the production of photoelectrons on the vacuum chamberwall, the beam emittance, lattice optics, and the secondary-electron yield model. We report on progress in understanding the cloud buildup and decay mechanisms in magnetic fields and in field-free regions, addressing quantitatively the precise determination of the physical parameters of the modeling. Validation of these models will serve as essential input in the design of damping rings for future high-energy linear colliders.

  6. Excitation and deexcitation of N2 molecular levels. Induced fluorescence by electrons and laser

    International Nuclear Information System (INIS)

    Perez Fernandez-Mayoralas, A.

    1989-01-01

    The electron impact excitation followed by fluorescence induced by N 2 -laser absorption was used to study the lifetime of the lowest vibrational level of the B 3 π g electronic state of N 2 . The experimental result of this work is 13 + 1 μs. To measure the lifetime of B 3 π g (v=2,3,5,6,7,8) levels the delayed coincidence method by electron impact was use. The lifetime values were compared with recent experimental and theoretical results. The relative intensi-ties of 3 π g --- A 3 Σ Ω + system bands, in the range (6540-10500 A o ) was measured using a hollow cathode lamp as spectral source. The relative transition moments and its dependence versus the r-centroid was obtained. Total cross sections for electron scattering by N molecules in the range 600 - 5000 eV have been obtained from measurements of the attenuation of a linear electron beam. The results have been compared with available experimental cross sections and with theoretical calculations based on the first Born approximation. (Author)

  7. Decomposition of organic pollutants in industrial Effluent induced by advanced oxidation process with Electron beam irradiation

    International Nuclear Information System (INIS)

    Duarte, C.L.; Sampa, M.H.O.; Rela, P.R.; Oikawa, H.; Silveira, C.G.

    2001-01-01

    Advanced Oxidation Process (AOP) by electron beam irradiation induce the decomposition of pollutants in industrial effluent. Experiments were conducted using a Radiation Dynamics Electron Beam Accelerator with 1.5 MeV energy and 37 Kew power. Experiments were conducted using samples from a Governmental Wastewater Treatment Plant (WTP) that receives about 20% of industrial wastewater, with the objective of use the electrons beam technology to destroy the refractory organic pollutants. Samples from WTP main Industrial Receiver Unit influent (IRU), Coarse Bar Screens effluent (CBS), Medium Bar Screens effluent (MBS), Primary Sedimentation effluent (PS) and Final Effluent (FE), were collected and irradiated in the electron beam accelerator in a batch system. The delivered doses were 5.0kGy, 10.0kGy and 20.0kGy. The electron beam irradiation showed be efficient on destroying the organic compounds delivered in these effluents mainly chloroform, dichloroethane, methyl isobutyl ketone, benzene, toluene, xylene, phenol. The necessary dose to remove 90% of the most organic compounds from industry effluent was 20 kGy. The removal of organic compounds from this complex mixture were described by the destruction G value (Gd) that were obtained for those compounds in different initial concentration and compared with literature

  8. Electron microscopic study of spontaneous and experimentally induced leukemia in IRC mice

    International Nuclear Information System (INIS)

    Hiraki, S.; Ranadive, K.J.; Dmochowski, L.

    1974-01-01

    Spontaneous, serially transplanted, and experimentally induced leukemias of ICRC mice were studied by electron microscopy in an attempt to detect the presence of virus particles, if any, and to observe the influence of chemical and hormonal treatment on the presence of these virus particles. The first series of experiments included spontaneous, serially transplanted, and radiation-induced leukemia. The paucity of type C virus particles was quite conspicuous in spontaneous leukemia. Serially transplanted and radiation-accelerated leukemic lesions showed the presence of some type C and intracisternal type A particles. Found in two of these leukemic lesions (thymus and lymphosarcoma), in addition to type C virus particles, were budding and some mature type B virus particles, and numerous intracytoplasmic type A particles. ''Viropexis'' of type B virus particles has been observed in the lymphosarcoma and in a leukemic thymus gland. The second series of experiments included leukemia induced in ovariectomized ICRC mice with 20-methylcholanthrene (MCA), pituitary transplants, and ovarian hormones (estradiol and estradiol-progesterone). In ovariectomized ICRC mice, leukemic lesions induced by MCA or pituitary transplants, or by MCA and pituitary transplants, showed type C virus particles and, in most cases, intracisternal type A particles. In leukemia induced in ovariectomized ICRC mice by MCA and estradiol, numerous intracytoplasmic type A particles were observed but no type C virus particles

  9. Study of electron kinetics in nitrogen plasma induced by CO2 laser radiation

    Science.gov (United States)

    Nassef, O. Aied; Gamal, Yosr E. E.-D.

    2017-12-01

    In the present work, a numerical modeling is performed to study the electron kinetics in nitrogen plasma induced by CO2 laser radiation operating at wavelength 9.621 μm, and pulse duration of 60 ns corresponding to the measurements carried out by Camacho et al. (J Phys B At Mol Opt Phys 40:4573, 2007). In this experiment, the breakdown threshold intensity is determined for molecular nitrogen over a pressure range 301-760 torr. A previously developed electron cascade model (Evans and Gamal in J Phys D Appl Phys 13:1447, 1980) is modified and applied. This model is based on numerical solution of a time-dependent energy equation and a set of rate equations that describe the time variation of the formed excited states population. The effect of breakdown mechanism is decided through the calculations of the threshold intensity as a function of gas pressure considering the various physical processes that might take place during the interaction. The individual effect of each loss process on the electron energy distribution function and its parameters is studied. This study is performed at the lowest and highest values of the experimentally tested gas pressure range namely; 301 and 760 torr. The obtained results clarified the exact contribution of each loss process to the breakdown of nitrogen induced by CO2 laser radiation.

  10. Evaluation of induced radioactivity in 10 MeV electron-irradiated spices

    Energy Technology Data Exchange (ETDEWEB)

    Furuta, Masakazu; Ito, Norio; Mizohata, Akira; Matsunami, Tadao; Katayama, Tadashi; Toratani, Hirokazu (Osaka Prefectural Univ., Sakai (Japan). Research Inst. for Advanced Science and Technology); Takeda, Atsuhiko

    1993-10-01

    In order to make clear appreciation to induced radioactivity in the irradiated foods, photonuclear reactions which could produce radioactivity at energies up to 10 MeV were listed up from elemental compositions of black pepper, white pepper, red pepper, ginger and turmeric. The samples were irradiated with 10 MeV electron from a linear accelerator to a dose of 100 kGy and radioactivity was measured. Induced radioactivity could not be detected significantly by gamma-ray spectrometry and beta-ray counting in the irradiated samples except for spiked samples which contain some photonuclear target nuclides in the list. From the amount of observed radioactivities of short-lived photonuclear products in the spiked samples and calculation of H[sub 50] according to ICRP Publication 30, it was concluded that the induced radioactivity and its biological effects in the 10 MeV electron-irradiated natural samples were negligible in comparison with natural radioactivity from [sup 40]K contained in the samples. (J.P.N.).

  11. In situ electric-field-induced contrast imaging of electronic transport pathways in nanotube-polymer composites

    Science.gov (United States)

    Jesse, Stephen; Guillorn, Michael A.; Ivanov, Ilia N.; Puretzky, Alexander A.; Howe, Jane Y.; Britt, Phillip F.; Geohegan, David B.

    2006-07-01

    An electric-field-induced contrast mechanism for scanning electron microscopy is reported which permits the visualization of embedded nanomaterials inside various matrices with high contrast and high definition. The high contrast is proposed to result from localized enhancement of secondary electron emission from the nanomaterials due to electric-field-induced changes in their work functions. By utilizing a stage that allows in situ current-voltage measurements inside a scanning electron microscope, single-walled carbon nanotubes embedded within polymethyl methacrylate films were visualized directly. In addition to the rapid assessment of nanotube dispersion within polymers, electric-field-induced contrast imaging enables the determination of percolation pathways. From the contrast in the images, the relative voltage at all points in the electron micrograph can be determined, providing a new mechanism to understand electronic percolation through nanoscale networks.

  12. Electron-beam-induced welding of 3D nano-objects from beneath

    Energy Technology Data Exchange (ETDEWEB)

    Moskalenko, A V [Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Burbridge, D J [Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Viau, G [ITODYS, UMR CNRS 7086, Universite Paris 7-Denis Diderot, case 7090, 2 place Jussieu, F-75251 Paris Cedex 05 (France); Gordeev, S N [Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom)

    2007-01-17

    Exposure of a sample to the electron beam in a scanning electron microscope (SEM) results in the growth of a film of amorphous carbon due to decomposition of hydrocarbon molecules, which are always present in small quantities in the SEM chamber. This growth is induced mainly by secondary electrons backscattered by atoms of both the sample and substrate. We show that, because the secondary electrons are spread beyond the exposed area, this deposit can be grown in areas of geometric shadow and therefore can be used for bonding of different complex 3D nano-objects to a substrate. This is demonstrated by welding 100 nm Fe-Co-Ni nanoparticles to the surface of 2D graphite. The tip of an atomic force microscope was used to probe the mechanical properties of the formed nanostructures. We observed that, for layers thicker than 25 nm, the nanoparticle is bonded so strongly that it is easier to break the particle than to separate it from the substrate.

  13. Light-induced confinement of electrons in stacked distorted graphene layers - a (TD-)DFT study.

    Science.gov (United States)

    Olejniczak, A; Cichy, B; Radosinski, L; Strek, W

    2017-04-19

    Recently observed white-light emission from graphene ceramics cannot be explained by black body radiation theory because of a relatively low temperature of the sample. Furthermore the intensity of the emission stays at the same level even at temperatures as low as 10 K, indicating the purely electronic nature of the observed emission. In this work a model of light emission from locally interacting stacked graphene layers after intense continuous wave laser excitation is proposed. After a light-induced sp 2 to sp 3 change of the hybridization sp 2 -nanodomains surrounded by sp 3 carbon atoms could be created and the electrons can be confined. Using DFT and TD-DFT methods followed by a molecular-like approach we examine the electronic structure and the optical properties of graphene (sp 2 ,sp 3 )-clusters. We show the quantized and well separated energy levels of electrons from the domain's interior and the possibility of emission in the NIR/VIS/UV range.

  14. Electronic spill-out induced spectral broadening in quantum hydrodynamic nanoplasmonics.

    Science.gov (United States)

    Li, Xiaoming; Fang, Hui; Weng, Xiaoyu; Zhang, Lichao; Dou, Xiujie; Yang, Aiping; Yuan, Xiaocong

    2015-11-16

    The hydrodynamic theory is a powerful tool to study the nonlocal effects in metallic nanostructures that are too small to obey classical electrodynamics while still too large to be handled with a full quantum-mechanical theory. The existing hydrodynamic model can give accurate quantitative predictions for the plasmonic resonance shifts in metallic nanoplasmonics, yet is not able to predict the spectral width which is usually taken as a pre-set value instead. By taking account the fact that due to electron density spill-out from a surface, the Coulomb interaction screening is less efficient close the surface thus leads to a higher electron-electron scattering rate in this paper, we study how the electron-density-related damping rate induced by such Coulomb interaction will affect the plasmonic spectral broadening. We perform the simulation on a Na nanowire, which shows that the absorption spectra width is wider when the size of the nanowire becomes smaller. This result is consistent well with the reported experiment. Therefore, our theoretical model extends the existing hydrodynamic model and can provide much more quantum insight about nonlocal effects in metallic nanostructures.

  15. Cluster analysis for the probability of DSB site induced by electron tracks

    Energy Technology Data Exchange (ETDEWEB)

    Yoshii, Y. [Biological Research, Education and Instrumentation Center, Sapporo Medical University, Sapporo 060-8556 (Japan); Graduate School of Health Sciences, Hokkaido University, Sapporo 060-0812 (Japan); Sasaki, K. [Faculty of Health Sciences, Hokkaido University of Science, Sapporo 006-8585 (Japan); Matsuya, Y. [Graduate School of Health Sciences, Hokkaido University, Sapporo 060-0812 (Japan); Date, H., E-mail: date@hs.hokudai.ac.jp [Faculty of Health Sciences, Hokkaido University, Sapporo 060-0812 (Japan)

    2015-05-01

    To clarify the influence of bio-cells exposed to ionizing radiations, the densely populated pattern of the ionization in the cell nucleus is of importance because it governs the extent of DNA damage which may lead to cell lethality. In this study, we have conducted a cluster analysis of ionization and excitation events to estimate the number of double-strand breaks (DSBs) induced by electron tracks. A Monte Carlo simulation for electrons in liquid water was performed to determine the spatial location of the ionization and excitation events. The events were divided into clusters by using the density-based spatial clustering of applications with noise (DBSCAN) algorithm. The algorithm enables us to sort out the events into the groups (clusters) in which a minimum number of neighboring events are contained within a given radius. For evaluating the number of DSBs in the extracted clusters, we have introduced an aggregation index (AI). The computational results show that a sub-keV electron produces DSBs in a dense formation more effectively than higher energy electrons. The root-mean square radius (RMSR) of the cluster size is below 5 nm, which is smaller than the chromatin fiber thickness. It was found that this size of clustering events has a high possibility to cause lesions in DNA within the chromatin fiber site.

  16. Chemical tuning of PtC nanostructures fabricated via focused electron beam induced deposition

    International Nuclear Information System (INIS)

    Plank, Harald; Gspan, Christian; Kothleitner, Gerald; Hofer, Ferdinand; Haber, Thomas

    2013-01-01

    The fundamental dependence between process parameters during focused electron beam induced deposition and the chemistry of functional PtC nanostructures have been studied via a multi-technique approach using SEM, (S)TEM, EELS, AFM, and EFM. The study reveals that the highest Pt contents can only be achieved by an ideal balance between potentially dissociating electrons and available precursor molecules on the surface. For precursor regimes apart from this situation, an unwanted increase of carbon is observed which originates from completely different mechanisms: (1) an excess of electrons leads to polymerization of precursor fragments whereas (2) a lack of electrons leads to incompletely dissociated precursor molecules incorporated into the nanostructures. While the former represents an unwanted class of carbon, the latter condition maximizes the volume growth rates and allows for post-growth curing strategies which can strongly increase the functionality. Furthermore, the study gives an explanation of why growing deposits can dynamically change their chemistry and provides a straightforward guide towards more controlled fabrication conditions. (paper)

  17. Strain-Induced Enhancement of the Electron Energy Relaxation in Strongly Correlated Superconductors

    Directory of Open Access Journals (Sweden)

    C. Gadermaier

    2014-03-01

    Full Text Available We use femtosecond optical spectroscopy to systematically measure the primary energy relaxation rate Γ_{1} of photoexcited carriers in cuprate and pnictide superconductors. We find that Γ_{1} increases monotonically with increased negative strain in the crystallographic a axis. Generally, the Bardeen-Shockley deformation potential theorem and, specifically, pressure-induced Raman shifts reported in the literature suggest that increased negative strain enhances electron-phonon coupling, which implies that the observed direct correspondence between a and Γ_{1} is consistent with the canonical assignment of Γ_{1} to the electron-phonon interaction. The well-known nonmonotonic dependence of the superconducting critical temperature T_{c} on the a-axis strain is also reflected in a systematic dependence T_{c} on Γ_{1}, with a distinct maximum at intermediate values (∼16  ps^{−1} at room temperature. The empirical nonmonotonic systematic variation of T_{c} with the strength of the electron-phonon interaction provides us with unique insight into the role of electron-phonon interaction in relation to the mechanism of high-T_{c} superconductivity as a crossover phenomenon.

  18. Electron injection studies of radiation induced positive charge in MOS devices

    International Nuclear Information System (INIS)

    Aitken, J.M.; DiMaria, D.J.; Young, D.R.

    1976-01-01

    Avalanche injection and internal photo-emission techniques have been used to study the capture of electrons by positive charges introduced into the oxide layers of MOS capacitors. These two techniques have been used to study the positive charge in Al gate and poly-Si gate capacitors. The electron capture cross-section of this charge has been found to depend on the composition of the inerface; positive charge at the Si interface tends to have a coulombic electron capture cross-section (approximately 4 x 10 -13 cm 2 ), while that at the aluminum interface has a non-coulombic electron capture cross-section (less than or equal to 10 -14 cm 2 ). The location of the positive charge induced by radiation under positive or negative bias has been determined in a completely non-destructive manner by photocurrent-voltage experiments. It has been found that under a positive irradiation bias, positive space charge accumulates within approximately 50 A of the Si-SiO 2 interface, while under a negative bias, the space charge is within approximately 50 A of the Al-SiO 2 interface. In both cases there is evidence for some charge at the other interface introduced by the irradiation

  19. Extra-electron induced covalent strengthening and generalization of intrinsic ductile-to-brittle criterion

    Science.gov (United States)

    Niu, Haiyang; Chen, Xing-Qiu; Liu, Peitao; Xing, Weiwei; Cheng, Xiyue; Li, Dianzhong; Li, Yiyi

    2012-10-01

    Traditional strengthening ways, such as strain, precipitation, and solid-solution, come into effect by pinning the motion of dislocation. Here, through first-principles calculations we report on an extra-electron induced covalent strengthening mechanism, which alters chemical bonding upon the introduction of extra-valence electrons in the matrix of parent materials. It is responsible for the brittle and high-strength properties of Al12W-type compounds featured by the typical fivefold icosahedral cages, which are common for quasicrystals and bulk metallic glasses (BMGs). In combination with this mechanism, we generalize ductile-to-brittle criterion in a universal hyperbolic form by integrating the classical Pettifor's Cauchy pressure with Pugh's modulus ratio for a wide variety of materials with cubic lattices. This study provides compelling evidence to correlate Pugh's modulus ratio with hardness of materials and may have implication for understanding the intrinsic brittleness of quasicrystals and BMGs.

  20. Relation between molecular electronic structure and nuclear spin-induced circular dichroism

    DEFF Research Database (Denmark)

    Štěpánek, Petr; Coriani, Sonia; Sundholm, Dage

    2017-01-01

    with the spatial distribution of the excited states and couplings between them, reflecting changes in molecular structure and conformation. This constitutes a marked difference to the nuclear magnetic resonance (NMR) chemical shift, which only reflects the local molecular structure in the ground electronic state......The recently theoretically described nuclear spin-induced circular dichroism (NSCD) is a promising method for the optical detection of nuclear magnetization. NSCD involves both optical excitations of the molecule and hyperfine interactions and, thus, it offers a means to realize a spectroscopy...... with spatially localized, high-resolution information. To survey the factors relating the molecular and electronic structure to the NSCD signal, we theoretically investigate NSCD of twenty structures of the four most common nucleic acid bases (adenine, guanine, thymine, cytosine). The NSCD signal correlates...

  1. Spectroscopic Evidence for Exceptional Thermal Contribution to Electron-Beam Induced Fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Caldwell, Marissa A.; Haynor, Ben; Aloni, Shaul; Ogletree, D. Frank; Wong, H.-S. Philip; Urban, Jeffrey J.; Milliron, Delia J.

    2010-11-16

    While electron beam induced fragmentation (EBIF) has been reported to result in the formation of nanocrystals of various compositions, the physical forces driving this phenomenon are still poorly understood. We report EBIF to be a much more general phenomenon than previously appreciated, operative across a wide variety of metals, semiconductors and insulators. In addition, we leverage the temperature dependent bandgap of several semiconductors to quantify -- using in situ cathodoluminescence spectroscopy -- the thermal contribution to EBIF, and find extreme temperature rises upwards of 1000K.

  2. Spin–orbit coupling induced magnetoresistance oscillation in a dc biased two-dimensional electron system

    International Nuclear Information System (INIS)

    Wang, C M; Lei, X L

    2014-01-01

    We study dc-current effects on the magnetoresistance oscillation in a two-dimensional electron gas with Rashba spin-orbit coupling, using the balance-equation approach to nonlinear magnetotransport. In the weak current limit the magnetoresistance exhibits periodical Shubnikov-de Haas oscillation with changing Rashba coupling strength for a fixed magnetic field. At finite dc bias, the period of the oscillation halves when the interbranch contribution to resistivity dominates. With further increasing current density, the oscillatory resistivity exhibits phase inversion, i.e., magnetoresistivity minima (maxima) invert to maxima (minima) at certain values of the dc bias, which is due to the current-induced magnetoresistance oscillation. (paper)

  3. Quantitative measurement of lightning-induced electron precipitation using VLF remote sensing

    Science.gov (United States)

    Peter, William Bolton

    This dissertation examines the detection of lightning-induced energetic electron precipitation via subionospheric Very Low Frequency (VLF) remote sensing. The primary measurement tool used is a distributed set of VLF observing sites, the Holographic Array for Ionospheric/Lightning Research (HAIL), located along the eastern side of the Rocky Mountains in the Central United States. Measurements of the VLF signal perturbations indicate that 90% of the precipitation occurs over a region ˜8 degrees in latitudinal extent, with the peak of the precipitation poleward displaced ˜7 degrees from the causative discharge. A comparison of the VLF signal perturbations recorded on the HAIL array with a comprehensive model of LEP events allows for the quantitative measurement of electron precipitation and ionospheric density enhancement with unprecedented quantitative detail. The model consists of three major components: a test-particle model of gyroresonant whistler-induced electron precipitation; a Monte Carlo simulation of energy deposition into the ionosphere; and a model of VLF subionospheric signal propagation. For the two representative LEP events studied, the model calculates peak VLF amplitude and phase perturbations within a factor of three of those observed, well within the expected variability of radiation belt flux levels. The modeled precipitated energy flux (E>45 keV) peaks at ˜1 x 10-2 [ergs s-1 cm -2], resulting in a peak loss of ˜0.001% from a single flux tube at L˜2.2, consistent with previous satellite measurements of LEP events. Metrics quantifying the ionospheric density enhancement (N ILDE) and the electron precipitation (Gamma) are strongly correlated with the VLF signal perturbations calculated by the model. A conversion ratio Psi relates VLF signal amplitude perturbations (DeltaA) to the time-integrated precipitation (100-300 keV) along the VLF path (Psi=Gamma / DeltaA). The total precipitation (100-300 keV) induced by one of the representative LEP

  4. Changes in the surface electronic states of semiconductor fine particles induced by high energy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Yamaki, Tetsuya; Asai, Keisuke; Ishigure, Kenkichi [Tokyo Univ. (Japan); Shibata, Hiromi

    1997-03-01

    The changes in the surface electronic states of Q-sized semiconductor particles in Langmuir-Blodgett (LB) films, induced by high energy ion irradiation, were examined by observation of ion induced emission and photoluminescence (PL). Various emission bands attributed to different defect sites in the band gap were observed at the initial irradiation stage. As the dose increased, the emissions via the trapping sites decreased in intensity while the band-edge emission developed. This suggests that the ion irradiation would remove almost all the trapping sites in the band gap. The low energy emissions, which show a multiexponential decay, were due to a donor-acceptor recombination between the deeply trapped carriers. It was found that the processes of formation, reaction, and stabilization of the trapping sites would predominantly occur under the photooxidizing conditions. (author)

  5. Tip-induced local strain on Mo S2/graphite detected by inelastic electron tunneling spectroscopy

    Science.gov (United States)

    Ko, Wonhee; Hus, Saban M.; Li, Xufan; Berlijn, Tom; Nguyen, Giang D.; Xiao, Kai; Li, An-Ping

    2018-03-01

    We report the detection of tip-induced local strain applied to the monolayer Mo S2 grown on a graphite substrate by scanning tunneling microscope. Monolayer Mo S2 behaves as both mechanical and tunneling barriers that prevent the tip from contacting the graphite while maintaining the tunneling current. Inelastic tunneling electron spectroscopy (IETS) is utilized to probe the phonon modes in graphite. As the tip pushes the sample, IETS reveals a continuous phonon softening in graphite, corroborated by a downward shift of the phonon energy as calculated by density-functional theory. Our results demonstrate a way to apply local mechanical strain and simultaneously detect the induced change in phonon modes by unitizing IETS with two-dimensional materials as a tunneling barrier.

  6. Extreme Ultraviolet Emission Spectrum of CO_2 Induced by Electron Impact at 200 eV

    Science.gov (United States)

    Kanik, I.; Ajello, J. M.; James, G. K.

    1993-01-01

    We present the extreme ultraviolet (EUV) emission spectrum of CO_2 induced by electronimpact at 200 eV. There are 36 spectral features which are identified with a resolution of 0.5 nmover the wavelength range of 40 to 125 nm. Absolute emission cross sections were obtained for eachof these features. The EUV emission spectrum induced by electron impact consist of atomicmultiplets of CI,II and OI,II,III as well as CO and CO^+ molecular band systems produced bydissociative excitation. The CI (119.4 nm) multiplet is the strongest feature of CI with a peak crosssection of 3.61 x 10^(-19) cm^2 at 200 eV. The strongest feature of OI in the EUV spectrum is theOI (99.0 nm) multiplet with a peak cross section of 3.59 x 10^(-19) cm^2 at 200 eV.

  7. Inhomogeneous width of oxygen-deficient centers induced by electron irradiation of silica

    International Nuclear Information System (INIS)

    D'Amico, Michele; Leone, Maurizio; Messina, Fabrizio; Cannas, Marco; Boscaino, Roberto

    2009-01-01

    We report a study of the luminescence activity of oxygen-deficient centers stabilized in as-grown synthetic silica, as compared with the same defects induced by β irradiation at increasing doses, ranging from 1.2x10 3 to 5x10 6 kGy. We experimentally observe a progressive broadening of the luminescence band with increasing total electron dose released on samples. By analyzing our data within a theoretical model capable of separating homogeneous and inhomogeneous contribution to the total luminescence linewidth, we observe that the increasing of the width is entirely ascribable to the inhomogeneous component which increases, in the most irradiated sample, of 60% with respect to the value in the as-grown sample. This effect can be due either to the progressive creation of new defects statistically exploring different sites of the matrix, or to a progressive structural transformation of silica host which affects the optical properties of induced point defects

  8. Impact of environmentally induced fluctuations on quantum mechanically mixed electronic and vibrational pigment states in photosynthetic energy transfer and 2D electronic spectra

    Energy Technology Data Exchange (ETDEWEB)

    Fujihashi, Yuta; Ishizaki, Akihito, E-mail: ishizaki@ims.ac.jp [Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585 (Japan); Fleming, Graham R. [Department of Chemistry, University of California, Berkeley and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2015-06-07

    Recently, nuclear vibrational contribution signatures in two-dimensional (2D) electronic spectroscopy have attracted considerable interest, in particular as regards interpretation of the oscillatory transients observed in light-harvesting complexes. These transients have dephasing times that persist for much longer than theoretically predicted electronic coherence lifetime. As a plausible explanation for this long-lived spectral beating in 2D electronic spectra, quantum-mechanically mixed electronic and vibrational states (vibronic excitons) were proposed by Christensson et al. [J. Phys. Chem. B 116, 7449 (2012)] and have since been explored. In this work, we address a dimer which produces little beating of electronic origin in the absence of vibronic contributions, and examine the impact of protein-induced fluctuations upon electronic-vibrational quantum mixtures by calculating the electronic energy transfer dynamics and 2D electronic spectra in a numerically accurate manner. It is found that, at cryogenic temperatures, the electronic-vibrational quantum mixtures are rather robust, even under the influence of the fluctuations and despite the small Huang-Rhys factors of the Franck-Condon active vibrational modes. This results in long-lasting beating behavior of vibrational origin in the 2D electronic spectra. At physiological temperatures, however, the fluctuations eradicate the mixing, and hence, the beating in the 2D spectra disappears. Further, it is demonstrated that such electronic-vibrational quantum mixtures do not necessarily play a significant role in electronic energy transfer dynamics, despite contributing to the enhancement of long-lived quantum beating in 2D electronic spectra, contrary to speculations in recent publications.

  9. Nanoscale Control of Molecular Self-Assembly Induced by Plasmonic Hot-Electron Dynamics.

    Science.gov (United States)

    Simoncelli, Sabrina; Li, Yi; Cortés, Emiliano; Maier, Stefan A

    2018-03-27

    Self-assembly processes allow designing and creating complex nanostructures using molecules as building blocks and surfaces as scaffolds. This autonomous driven construction is possible due to a complex thermodynamic balance of molecule-surface interactions. As such, nanoscale guidance and control over this process is hard to achieve. Here we use the highly localized light-to-chemical-energy conversion of plasmonic materials to spatially cleave Au-S bonds on predetermined locations within a single nanoparticle, enabling a high degree of control over this archetypal system for molecular self-assembly. Our method offers nanoscale precision and high-throughput light-induced tailoring of the surface chemistry of individual and packed nanosized metallic structures by simply varying wavelength and polarization of the incident light. Assisted by single-molecule super-resolution fluorescence microscopy, we image, quantify, and shed light onto the plasmon-induced desorption mechanism. Our results point toward localized distribution of hot electrons, contrary to uniformly distributed lattice heating, as the mechanism inducing Au-S bond breaking. We demonstrate that plasmon-induced photodesorption enables subdiffraction and even subparticle multiplexing. Finally, we explore possible routes to further exploit these concepts for the selective positioning of nanomaterials and the sorting and purification of colloidal nanoparticles.

  10. Dynamic molecular structure retrieval from low-energy laser-induced electron diffraction spectra

    Science.gov (United States)

    Vu, Dinh-Duy T.; Phan, Ngoc-Loan T.; Hoang, Van-Hung; Le, Van-Hoang

    2017-12-01

    A recently developed quantitative rescattering theory showed that a laser-free elastic cross section can be separated from laser-induced electron diffraction (LIED) spectra. Based upon this idea, Blaga et al investigated the possibility of reconstructing molecular structure from LIED spectra (2012 Nature 483 7388). In the above study, an independent atoms model (IAM) was used to interpret high-energy electron–molecule collisions induced by a mid-infrared laser. Our research aims to extend the application range of this structural retrieval method to low-energy spectra induced by more common near-infrared laser sources. The IAM is insufficient in this case, so we switch to a more comprehensive model—the multiple scattering (MS) theory. From the original version concerning only neutral targets, we upgrade the model so that it is compatible with electron–ion collisions at low energy. With available LIED experiment data of CO2 and O2, the upgraded MS is shown to be greatly effective as a tool for molecular imaging from spectra induced by a near-infrared laser. The captured image is at about 2 fs after the ionization, shorter than the period 4–6 fs by using the mid-infrared laser in Blaga’s experiment.

  11. Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Bäcke, Olof, E-mail: obacke@chalmers.se [Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg (Sweden); Lindqvist, Camilla; Diaz de Zerio Mendaza, Amaia [Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg (Sweden); Gustafsson, Stefan [Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg (Sweden); Wang, Ergang; Andersson, Mats R.; Müller, Christian [Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg (Sweden); Kristiansen, Per Magnus [Institute of Polymer Nanotechnology (INKA), FHNW University of Applied Science and Arts Northwestern Switzerland, 5210 Windisch (Switzerland); Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, 5232 Villigen (Switzerland); Olsson, Eva, E-mail: eva.olsson@chalmers.se [Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg (Sweden)

    2017-05-15

    We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices. To investigate how electron irradiation affects the thermal stability of polymer:fullerene films, a model bulk-heterojunction film based on a thiophene-quinoxaline copolymer and a fullerene derivative was heat-treated in-situ in a transmission electron microscope. In areas of the film that exposed to the electron beam the nanostructure of the film remained stable, while the nanostructure in areas not exposed to the electron beam underwent large phase separation and nucleation of fullerene crystals. UV–vis spectroscopy shows that the polymer:fullerene films are stable for electron doses up to 2000 kGy. - Highlights: • Thermal stability of a polymer: fullerne blend is increased using electron irradiation. • Using in-situ transmission electron microscopy the nanostructure is studied. • Electron irradiation stops phase separation between the polymer and fullerene. • Electron irradiation quenches the formation and nucleation of fullerene crystals.

  12. Mechanically induced intramolecular electron transfer in a mixed-valence molecular shuttle

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, J. C.; Fahrenbach, A. C.; Dyar, S. M.; Frasconi, M.; Giesener, M. A.; Zhu, Z.; Liu, Z.; Hartlieb, K. J.; Carmieli, R.; Wasielewski, M. R.; Stoddart, J. F.

    2012-06-08

    The kinetics and thermodynamics of intramolecular electron transfer (IET) can be subjected to redox control in a bistable [2]rotaxane comprised of a dumbbell component containing an electron-rich 1,5-dioxynaphthalene (DNP) unit and an electron-poor phenylene-bridged bipyridinium (P-BIPY2+) unit and a cyclobis (paraquat-p-phenylene) (CBPQT4+) ring component. The [2]rotaxane exists in the ground-state co-conformation (GSCC) wherein the CBPQT4+ ring encircles the DNP unit. Reduction of the CBPQT4+ leads to the CBPQT2(•+) diradical dication while the P-BIPY2+ unit is reduced to its P-BIPY•+ radical cation. A radical-state co-conformation (RSCC) results from movement of the CBPQT2(•+) ring along the dumbbell to surround the P-BIPY•+ unit. This shuttling event induces IET to occur between the pyridinium redox centers of the P-BIPY•+ unit, a property which is absent between these redox centers in the free dumbbell and in the 1:1 complex formed between the CBPQT2(•+) ring and the radical cation of methyl-phenylene-viologen (MPV•+). Using electron paramagnetic resonance (EPR) spectroscopy, the process of IET was investigated by monitoring the line broadening at varying temperatures and determining the rate constant (kET = 1.33 × 107 s-1) and activation energy (ΔG‡ = 1.01 kcal mol-1) for electron transfer. These values were compared to the corresponding values predicted, using the optical absorption spectra and Marcus–Hush theory.

  13. Superluminescence from an optically pumped molecular tunneling junction by injection of plasmon induced hot electrons

    Directory of Open Access Journals (Sweden)

    Kai Braun

    2015-05-01

    Full Text Available Here, we demonstrate a bias-driven superluminescent point light-source based on an optically pumped molecular junction (gold substrate/self-assembled molecular monolayer/gold tip of a scanning tunneling microscope, operating at ambient conditions and providing almost three orders of magnitude higher electron-to-photon conversion efficiency than electroluminescence induced by inelastic tunneling without optical pumping. A positive, steadily increasing bias voltage induces a step-like rise of the Stokes shifted optical signal emitted from the junction. This emission is strongly attenuated by reversing the applied bias voltage. At high bias voltage, the emission intensity depends non-linearly on the optical pump power. The enhanced emission can be modelled by rate equations taking into account hole injection from the tip (anode into the highest occupied orbital of the closest substrate-bound molecule (lower level and radiative recombination with an electron from above the Fermi level (upper level, hence feeding photons back by stimulated emission resonant with the gap mode. The system reflects many essential features of a superluminescent light emitting diode.

  14. Measurement of NdFeB permanent magnets demagnetization induced by high energy electron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Temnykh, Alexander B. [Wilson Lab, Cornell University, LEPP, Ithaca, NY 14850 (United States)], E-mail: abt6@cornell.edu

    2008-03-11

    Demagnetization of NdFeB permanent magnets has been measured as function of radiation dose induced by high energy electrons. The magnet samples were of different intrinsic coercive forces, {approx_equal}12 and {approx_equal}20KOe, dimensions and direction of magnetization. 5 GeV electron beam from 12 GeV Cornell Synchrotron was used as a radiation source. A calorimetric technique was employed for radiation dose measurement. Results indicated that depending on the sample intrinsic coercive force, shape and direction of magnetization the radiation dose causing 1% of demagnetization of the sample varies from 0.0765{+-}0.005Mrad to 11.3{+-}3.0Mrad, i.e., by more than a factor of 100. Experimental data analysis revealed that demagnetization of the given sample induced by radiation is strongly correlated with the sample demagnetizing temperature. This correlation was approximated by an exponential function with two parameters obtained from the data fitting. The function can be used to predict the critical radiation dose for permanent magnet assemblies like undulator magnets based on its demagnetizing temperature. The latter (demagnetization temperature) can be determined at the design stage from 3-D magnetic modeling and permanent magnet material properties.

  15. In Vivo Cytogenotoxicity and Oxidative Stress Induced by Electronic Waste Leachate and Contaminated Well Water

    Directory of Open Access Journals (Sweden)

    Adeyinka M. Gbadebo

    2013-07-01

    Full Text Available Environmental, plant and animal exposure to hazardous substances from electronic wastes (e-wastes in Nigeria is increasing. In this study, the potential cytogenotoxicity of e-wastes leachate and contaminated well water samples obtained from Alaba International Electronic Market in Lagos, Nigeria, using induction of chromosome and root growth anomalies in Allium cepa, and micronucleus (MN in peripheral erythrocytes of Clarias gariepinus, was evaluated. The possible cause of DNA damage via the assessments of liver malondialdehyde (MDA, catalase (CAT, reduced glutathione (GSH and superoxide dismutase (SOD as indicators of oxidative stress in mice was also investigated. There was significant (p < 0.05 inhibition of root growth and mitosis in A. cepa. Cytological aberrations such as spindle disturbance, C-mitosis and binucleated cells, and morphological alterations like tumor and twisting roots were also induced. There was concentration-dependent, significant (p < 0.05 induction of micronucleated erythrocytes and nuclear abnormalities such as blebbed nuclei and binucleated erythrocytes in C. gariepinus. A significant increase (p < 0.001 in CAT, GSH and MDA with concomitant decrease in SOD concentrations were observed in the treated mice. Pb, As, Cu, Cr, and Cd analyzed in the tested samples contributed significantly to these observations. This shows that the well water samples and leachate contained substances capable of inducing somatic mutation and oxidative stress in living cells; and this is of health importance in countries with risk of e-wastes exposure.

  16. Radiation-induced energy migration within solid DNA: The role of misonidazole as an electron trap

    International Nuclear Information System (INIS)

    Al-Kazwini, A.T.; O'Neill, P.; Adams, G.E.; Fielden, E.M.

    1990-01-01

    The in-pulse luminescence emission from solid DNA produced upon irradiation with electron pulses of energy below 260 keV has been investigated in vacuo at 293 K to gain an insight into the existence of radiation-induced charge/energy migration within DNA. The DNA samples contained misonidazole in the range 3 to 330 base pairs per misonidazole molecule. Under these conditions greater than 90% of the total energy is deposited in the DNA. The in-pulse radiation-induced luminescence spectrum of DNA was found to be critically dependent upon the misonidazole content of DNA. The luminescence intensity from the mixtures decreases with increasing content of misonidazole, and at the highest concentration, the intensity at 550 nm is reduced to 50% of that from DNA only. In the presence of 1 atm of oxygen, the observed emission intensity from DNA in the wavelength region 350-575 was reduced by 35-40% compared to that from DNA in vacuo. It is concluded that electron migration can occur in solid mixtures of DNA over a distance of up to about 100 base pairs

  17. A quantitative comparison of lightning-induced electron precipitation and VLF signal perturbations

    Science.gov (United States)

    Peter, W. B.; Inan, U. S.

    2007-12-01

    VLF signal perturbations recorded on the Holographic Array for Ionospheric/Lightning Research (HAIL) are quantitatively related to a comprehensive model of lightning-induced electron precipitation (LEP) events. The model consists of three major components: a test-particle model of gyroresonant whistler-induced electron precipitation, a Monte Carlo simulation of energy deposition into the ionosphere, and a model of VLF subionospheric signal propagation. For the two representative LEP events studied, the model calculates peak VLF amplitude perturbations within a factor of three of those observed, well within the expected variability of radiation belt flux levels. The phase response of the observed VLF signal to precipitation varied dramatically over the course of the two nights and this variability in phase response is not properly reproduced by the model. The model calculates a peak in the precipitation that is poleward displaced ~6° from the causative lightning flash, consistent with observations. The modeled precipitated energy flux (E > 45 keV) peaks at ~1 × 10-2 (ergs s-1 cm-2), resulting in a peak loss of ~0.001% from a single flux tube at L ~ 2.2, consistent with previous satellite measurements of LEP events. The precipitation calculated by the model is highly dependent on the near-loss-cone trapped radiation belt flux levels assumed, and hence our main objective is not to compare the model calculations and the VLF signal observations on an absolute basis but is rather to develop metrics with which we can characterize the VLF signal perturbations recorded on HAIL in terms of the associated precipitation flux. Metrics quantifying the ionospheric density enhancement (N ILDE) and the electron precipitation (Γ) along a VLF signal path are strongly correlated with the VLF signal perturbations calculated by the model. A conversion ratio Ψ, relating VLF signal amplitude perturbations (ΔA) to the time-integrated precipitation (100-300 keV) along the VLF path (

  18. Gamma and electron beam radiation induced physico-chemical modifications of poly(propylene)

    Science.gov (United States)

    Yagoubi, N.; Peron, R.; Legendre, B.; Grossiord, J. L.; Ferrier, D.

    1999-05-01

    The homopolymer PP, a plastic material used as packaging and for medical products, must be subjected to a form of sterilization. Nowadays, one kind of this technology uses ionising radiation, which can be γ-rays or electron beams. In order to study the structural modifications of polymer syringes which could occur following these treatments at different doses (25-150 kGy), several analytical techniques have been used. DSC provided information on changes in the cristallinity of the polymer. The thermal evaluation was supplemented by testing the rheological properties of polypropylene. In addition, Reversed Phase Liquid Chromatography (HPLC) with a quaternary elution gradient was carried out for the evaluation of the degradation of the additives. Thermogravimetric analysis (TGA) coupled with Fourier transform infrared (TGA/FTIR) was used to measure the desorption of food simulating liquid (CH 2Cl 2). First, the results obtained proved that the γ-rays as well as the electron beam induced degradation of the polymer and its additives. Next, we compared the effects of gamma and electron beam irradiation to determine which of these two processes better maintained the integrity of the irradiated product.

  19. Natural and induced by gamma radiation electronic properties of phosphate and silica glasses

    International Nuclear Information System (INIS)

    Barthe, Th.

    1980-03-01

    The first part of the thesis concerns an experimental study of the electric and electronic properties of phosphate glasses activated with silver at different temperatures. The conductivity of these glasses shows an interesting aspect i.e. these are two characteristic temperature ranges. Above 230 K the model of Arrhenius is respected with an average activation energy of 0.80 eV. Below 230 K the activation energy falls rapidly to 50 meV. These results are compared with those obtained in the study of radio-photoluminescence under continuous gamma irradiation. The phenomena question the transitory kinetic processes, the linearity of which can be considered as the resultant of the stationary equilibrium of the population of the classes corresponding to the metastable states. These processes are thermically activated with the variation of the activation energy over the same temperature ranges. It would seen that the observed effects are due to a particular structure. The second part of this work deals with the conduction induced by gamma radiation in silica. The results can be explained by Onsager's theory of dissociation of the created electron-hole pairs. This method allows the determination of the yield of free electron-hole pairs at zero field and of the ionization energy: both are important parameters in the dosimetric study of ionizing radiation. (author)

  20. Time-of-flight MeV-SIMS with beam induced secondary electron trigger

    Energy Technology Data Exchange (ETDEWEB)

    Schulte-Borchers, Martina, E-mail: marschul@phys.ethz.ch; Döbeli, Max; Müller, Arnold Milenko; George, Matthias; Synal, Hans-Arno

    2016-08-01

    A new Time-of-flight MeV Secondary Ion Mass Spectrometry (MeV-SIMS) setup was developed to be used with a capillary microprobe for molecular imaging with heavy primary ions at MeV energies. Due to the low output current of the ion collimating capillary a Time-of-flight (ToF) measurement method with high duty cycle is necessary. Secondary electrons from the sample surface and transmitted ions were studied as start signals. They enable measurements with a continuous primary beam and unpulsed ToF spectrometer. Tests with various primary ion beams and sample types have shown that a secondary electron signal is obtained from 30% to 40% of incident MeV particles. This provides a ToF start signal with considerably better time resolution than the one obtained from transmitted primary ions detected in a radiation hard gas ionization detector. Beam induced secondary electrons therefore allow for MeV-SIMS measurements with reasonable mass resolution at primary ion beam currents in the low fA range.

  1. Radioautographic measurement of electron-induced epidermal kinetic effects in different aged rats

    International Nuclear Information System (INIS)

    Sargent, E.V.; Burns, F.J.

    1987-01-01

    We have previously shown that the ability of rat epidermal cells to repair electron-induced DNA damage decreases as a function of age. The present investigation was performed to examine the relationship between this finding and sensitivity of epidermal cells to the cytotoxic effects of the radiation. Male CD rats at ages 2, 28, 100, 200, 420, and 728 days were injected with [ 3 H]-thymidine [( 3 H]Thd) at a dose of 2 mu Ci/g body weight. One hour later, the rats were anesthetized and the dorsal skin irradiated with various doses of 0.8 meV electrons at a dose rate of 660 rads/min. At 24 h after irradiation, radioautographs were made of a sheet of epidermis that was separated by trypsinization from the underlying dermis. Labeled cells were scored either as singlets or doublets (adjacent labeled cells). The percent labeled cells and percent labeled cells as doublets were determined. The estimated labeling index (the proportion of cells labeled by a single exposure to [ 3 H]Thd) of the epidermal basal layer decreased as a function of age. The slope of the semilog plot of the percent labeled cells as doublets as a function of electron dose indicates that the Do value decreases with increasing age. The results show, however, that the greatest difference in sensitivity occurs between 2-day (neonatal) and 28-day (pubescent) animals and again between 420-day (adult) and 728-day (senescent) animals

  2. Various categories of defects after surface alloying induced by high current pulsed electron beam irradiation

    International Nuclear Information System (INIS)

    Luo, Dian; Tang, Guangze; Ma, Xinxin; Gu, Le; Sun, Mingren; Wang, Liqin

    2015-01-01

    Highlights: • Four kinds of defects are found during surface alloying by high current electron beam. • Exploring the mechanism how these defects appear after irradiation. • Increasing pulsing cycles will help to get good surface quality. • Choosing proper energy density will increase surface quality. - Abstract: High current pulsed electron beam (HCPEB) is an attractive advanced materials processing method which could highly increase the mechanical properties and corrosion resistance. However, how to eliminate different kinds of defects during irradiation by HCPEB especially in condition of adding new elements is a challenging task. In the present research, the titanium and TaNb-TiW composite films was deposited on the carburizing steel (SAE9310 steel) by DC magnetron sputtering before irradiation. The process of surface alloying was induced by HCPEB with pulse duration of 2.5 μs and energy density ranging from 3 to 9 J/cm 2 . Investigation of the microstructure indicated that there were several forms of defects after irradiation, such as surface unwetting, surface eruption, micro-cracks and layering. How the defects formed was explained by the results of electron microscopy and energy dispersive spectroscopy. The results also revealed that proper energy density (∼6 J/cm 2 ) and multi-number of irradiation (≥50 times) contributed to high quality of alloyed layers after irradiation

  3. Light-Induced Conversion of Chemical Permeability to Enhance Electron and Molecular Transfer in Nanoscale Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Balgley, Renata; de Ruiter, Graham; Evmenenko, Guennadi; Bendikov, Tatyana; Lahav, Michal; van der Boom, Milko E.

    2016-12-21

    In this paper, we demonstrate how photochemically enhancing the permeability of metal–organic assemblies results in a significant enhancement of the electrochemical activity of metal complexes located within the assembly. The molecular assemblies consist of different layers of redox-active metal complexes ([M(mbpy-py)3][PF6]2; M = Ru or Os) that are separated by redox-inactive spacers consisting of 1,4-bis[2-(4-pyridyl)ethenyl]benzene (BPEB) and PdCl2 of variable thicknesses (0–13.4 nm). UV-irradiation (λ = 254 nm) of our assemblies induces a photochemical reaction in the redox-inactive spacer increasing the permeability of the assembly. The observed increase was evident by trapping organic (nBu4NBF4) and inorganic (NiCl2) salts inside the assemblies, and by evaluating the electrochemical response of quinones absorbed inside the molecular assemblies before and after UV irradiation. The increase in permeability is reflected by higher currents and a change in the directionality of electron transfer, i.e., from mono- to bidirectional, between the redox-active metal complexes and the electrode surface. The supramolecular structure of the assemblies dominates the overall electron transfer properties and overrules possible electron transfer mediated by the extensive π-conjugation of its individual organic components.

  4. Electron heating mode transition induced by mixing radio frequency and ultrahigh frequency dual frequency powers in capacitive discharges

    International Nuclear Information System (INIS)

    Sahu, B. B.; Han, Jeon G.

    2016-01-01

    Electron heating mode transitions induced by mixing the low- and high-frequency power in dual-frequency nitrogen discharges at 400 mTorr pressure are presented. As the low-frequency (13.56 MHz) power decreases and high-frequency (320 MHz) power increases for the fixed power of 200 W, there is a transition of electron energy distribution function (EEDF) from Druyvesteyn to bi-Maxwellian type characterized by a distinguished warm electron population. It is shown that this EEDF evolution is attributed to the transition from collisional to collisionless stochastic heating of the low-energy electrons.

  5. Electron beam-induced Fries rearrangement of arylsulfonamides and arylsulfonates in the crystalline state

    International Nuclear Information System (INIS)

    Kato, Jun; Yuasa, Kanako; Yamashita, Takashi; Maekawa, Yasunari; Yoshida, Masaru

    2003-01-01

    Electron beam (EB)-induced reactions of organic crystals containing a carbonyl or a sulfonyl group have been investigated. The EB irradiation of benzenesulfonanilide (BSA) in the crystalline state induced the Fries rearrangement to yield o- and p-aminodiphenylsulfones as the major and minor products, respectively. Several BSA derivatives also had the same reactivity, while benzanilide as the corresponding carbonyl compound did not rearrange under the same conditions. These results showed that the S-N bond could be cleaved selectively by EB irradiation but the C-N bond couldn't, which could take place only by the use of EB. The EB irradiation of phenyl p-toluenesulfonate (PTS) crystals gave not only Fries-type products but also the oxidation product. By comparing with the reactivity of liquid phenyl benzenesulfonate, the EB-induced Fries rearrangement was suggested to proceed under crystalline lattice restrictions. The G-values of arylsulfonamides and arylsulfonates were in the range of ca. 1-2 molecules per 100 eV of absorbed energy. This is the first Fries rearrangement via direct excitation by EB irradiation. (author)

  6. 3D magnetic nanostructures grown by focused electron and ion beam induced deposition

    Science.gov (United States)

    Fernandez-Pacheco, Amalio

    Three-dimensional nanomagnetism is an emerging research area, where magnetic nanostructures extend along the whole space, presenting novel functionalities not limited to the substrate plane. The development of this field could have a revolutionary impact in fields such as electronics, the Internet of Things or bio-applications. In this contribution, I will show our recent work on 3D magnetic nanostructures grown by focused electron and ion beam induced deposition. This 3D nano-printing techniques, based on the local chemical vapor deposition of a gas via the interaction with electrons and ions, makes the fabrication of complex 3D magnetic nanostructures possible. First, I will show how by exploiting different growth regimes, suspended Cobalt nanowires with modulated diameter can be patterned, with potential as domain wall devices. Afterwards, I will show recent results where the synthesis of Iron-Gallium alloys can be exploited in the field of artificial multiferroics. Moreover, we are developing novel methodologies combining physical vapor deposition and 3D nano-printing, creating Permalloy 3D nanostrips with controllable widths and lengths up to a few microns. This approach has been extended to more complex geometries by exploiting advanced simulation growth techniques combining Monte Carlo and continuum model methods. Throughout the talk, I will show the methodology we are following to characterize 3D magnetic nanostructures, by combining magneto-optical Kerr effect, scanning probe microscopy and electron and X-R magnetic imaging, and I will highlight some of the challenges and opportunities when studying these structures. I acknowledge funding from EPSRC and the Winton Foundation.

  7. Angle-differential observation of plasmon electrons in the double-differential cross-section spectra of fast-ion-induced electron ejection from C60

    Science.gov (United States)

    Kelkar, A. H.; Gulyás, L.; Tribedi, Lokesh C.

    2015-11-01

    We report on the measurement of double-differential distribution of soft electron emission from C60 fullerene, induced by a fast-moving Coulomb field of 76 MeV energy bare fluorine ions. A broad "plasmon-electron" peak, riding on the Coulomb-ionization continuum, is observed due to the deexcitation of the giant dipole plasmon resonance state in C60. The angular distribution of the plasmon electrons goes through a dip around 90°, which is contrary to that observed in ion-atom collisions measured in situ, indicating the alignment of the induced dipole moment along the projectile beam direction. A model based on the photoelectron angular distribution which is modified due to the ion-induced postcollisional interaction provides an excellent agreement with the observed asymmetric distribution. The distribution smoothly changes from a dip at 90° to a peak with the variation of ejected electron energy indicating transition from a collective plasmon behavior of the whole system to a single ion-atom interaction. The single-differential cross section was also derived, which preserves the signature of the collective excitation.

  8. Band-offset-induced lateral shift of valley electrons in ferromagnetic MoS2/WS2 planar heterojunctions

    Science.gov (United States)

    Ghadiri, Hassan; Saffarzadeh, Alireza

    2018-03-01

    Low-energy coherent transport and a Goos-Hänchen (GH) lateral shift of valley electrons in planar heterojunctions composed of normal MoS2 and ferromagnetic WS2 monolayers are theoretically investigated. Two types of heterojunctions in the forms of WS2/MoS2/WS2 (type-A) and MoS2/WS2/MoS2 (type-B) with incident electrons in the MoS2 region are considered in which the lateral shift of electrons is induced by band alignments of the two constituent semiconductors. It is shown that the type-A heterojunction can act as an electron waveguide due to electron confinement between the two WS2/MoS2 interfaces which cause the incident electrons with an appropriate incidence angle to propagate along the interfaces. In this case, the spin- and valley-dependent GH shifts of totally reflected electrons from the interface lead to separated electrons with distinct spin-valley indexes after traveling a sufficiently long distance. In the type-B heterojunction, however, transmission resonances occur for incident electron beams passing through the structure, and large spin- and valley-dependent lateral shift values in propagating states can be achieved. Consequently, the transmitted electrons are spatially well-separated into electrons with distinct spin-valley indexes. Our findings reveal that the planar heterojunctions of transition metal dichalcogenides can be utilized as spin-valley beam filters and/or splitters without external gating.

  9. Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope.

    Science.gov (United States)

    Bäcke, Olof; Lindqvist, Camilla; de Zerio Mendaza, Amaia Diaz; Gustafsson, Stefan; Wang, Ergang; Andersson, Mats R; Müller, Christian; Kristiansen, Per Magnus; Olsson, Eva

    2017-05-01

    We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices. To investigate how electron irradiation affects the thermal stability of polymer:fullerene films, a model bulk-heterojunction film based on a thiophene-quinoxaline copolymer and a fullerene derivative was heat-treated in-situ in a transmission electron microscope. In areas of the film that exposed to the electron beam the nanostructure of the film remained stable, while the nanostructure in areas not exposed to the electron beam underwent large phase separation and nucleation of fullerene crystals. UV-vis spectroscopy shows that the polymer:fullerene films are stable for electron doses up to 2000kGy. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. FEL induced electron bunch heating observed by a method based on synchronous phase detection

    CERN Document Server

    Hosaka, M; Katoh, M; Yamazaki, J; Hama, H

    2001-01-01

    A new method for monitoring instantaneous bunch length has been developed on the UVSOR storage ring. Based on the bunch length dependence of the loss factor, the bunch length can be derived from the synchronous phase shift. Experiments using this method were performed to observe the bunch lengthening associated with the free electron laser (FEL) power variation. From the detuning dependence of the bunch heating, it was found that additional energy spread mostly has a constant ratio to the intracavity laser power normalized by the beam current. However, at the best synchronism region, the induced energy spread exhibits a strong non-linearity against the normalized FEL power and hence the power saturation is accomplished.

  11. Low temperature annealing of electron irradiation induced defects in 4H-SiC

    International Nuclear Information System (INIS)

    Castaldini, Antonio; Cavallini, Anna; Rigutti, Lorenzo; Nava, Filippo

    2004-01-01

    Low temperature annealing of electron irradiation-induced deep levels in 4H-SiC is reported. The major deep level transient spectroscopy peak S2 associated with the energy level at E c -0.39 eV disappears in the temperature range 360-400 K, and some rearrangement of the peak S3, associated with the defect Z 1 /Z 2 with energy level at E c -0.5/E c -0.65 eV occurs in the temperature interval 400-470 K. A net free charge carrier concentration increase goes along with the disappearance of peak S2 at E c -0.39 eV, whereas the charge collection efficiency of the diode does not experience any significant change. An interpretation of the annealing of peak S2 on a microscopic scale is given

  12. Electron microscopy study of Ni induced crystallization in amorphous Si thin films

    Energy Technology Data Exchange (ETDEWEB)

    Radnóczi, G. Z.; Battistig, G.; Pécz, B., E-mail: pecz.bela@ttk.mta.hu [Institute for Technical Physics and Matl. Sci., Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1121 Budapest, Konkoly-Thege u. 29-33 (Hungary); Dodony, E. [Institute for Technical Physics and Matl. Sci., Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1121 Budapest, Konkoly-Thege u. 29-33, Hungary and Doctoral School of Physics at Eötvös Loránd University, 1117 (Hungary); Vouroutzis, N.; Stoemenos, J.; Frangis, N. [Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Kovács, A. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 (Germany)

    2015-02-17

    The crystallization of amorphous silicon is studied by transmission electron microscopy. The effect of Ni on the crystallization is studied in a wide temperature range heating thinned samples in-situ inside the microscope. Two cases of limited Ni source and unlimited Ni source are studied and compared. NiSi{sub 2} phase started to form at a temperature as low as 250°C in the limited Ni source case. In-situ observation gives a clear view on the crystallization of silicon through small NiSi{sub 2} grain formation. The same phase is observed at the crystallization front in the unlimited Ni source case, where a second region is also observed with large grains of Ni{sub 3}Si{sub 2}. Low temperature experiments show, that long annealing of amorphous silicon at 410 °C already results in large crystallized Si regions due to the Ni induced crystallization.

  13. Collisions induced dissociation and Ab initio study of azobenzene derivatives bond structure and electronic configuration

    Science.gov (United States)

    Rezaee, Mohammadreza; Compton, Robert

    2015-05-01

    Collision induced dissociation (CID) and ab initio calculations were utilized to study a few derivatives of azobenzene molecule and their product ions. High level computational methods along with large basis set size yield values in close agreement with the experimental results. Möller-Plesset and coupled-cluster theory including perturbative triple excitations, CCSD(T), method were performed to obtain a high accuracy estimation of the bond dissociation energy value. The electron affinities have been studied experimentally using the photoelectron spectroscopy method as well as theoretically using ab inito calculations. For the trans-2,2',6,6' tetra-fluoro azobenzene the bond dissociation has been experimentally determined to be 1.88 eV and the vertical detachment energy is 1.78 eV.

  14. Flow injection fluorescence determination of dopamine using a photo induced electron transfer (PET) boronic acid derivative

    International Nuclear Information System (INIS)

    Ebru Seckin, Z.; Volkan, Muervet

    2005-01-01

    An automated flow injection analysis system was developed for the fluorometric determination of dopamine in pharmaceutical injections. The method is based on the quenching effect of dopamine on m-dansylaminophenyl boronic acid (DAPB) fluorescence due to the reverse photo induced electron transfer (PET) mechanism. Effects of pH and interfering species on the determination of dopamine were examined. Calibration for dopamine, based on quenching data, was linear in the concentration range of 1.0 x 10 -5 to 1.0 x 10 -4 M. Detection limit (3 s) of the method was found to be 3.7 x 10 -6 M. Relative standard deviation of 1.2% (n = 10) was obtained with 1.0 x 10 -5 M dopamine standard solution. The proposed method was applied successfully for the determination of dopamine in pharmaceutical injection sample. The sampling rate was determined as 24 samples per hour

  15. Pressure-induced Novel Electronic State of Fe70Ni30 Invar Alloy

    Science.gov (United States)

    Oomi, Gendo; Saito, Ryohei; Ohashi, Masashi; Nakano, Tomohito

    The electrical resistance and magnetoresistance of Fe70Ni30 Invar alloy have been measured at high pressure up to 15 GPa. It is found that the coefficients of T2 term in the electrical resistance increases with increasing pressure but tends to saturate above 12 GPa suggesting a peak above 15 GPa, which implies a pressure-induced quantum phase transition. We found for the first time that the magnetoresistance at 4.2 K is negative below 11 GPa but becomes positive above 12 GPa. This corresponds to a crossover in the electronic state from localized moment regime to a paramagnetic or new magnetic state. The origins will be discussed briefly in connection with the recent experimental results and theoretical calculation.

  16. Parallel ion flow velocity measurement using laser induced fluorescence method in an electron cyclotron resonance plasma

    International Nuclear Information System (INIS)

    Yoshimura, Shinji; Okamoto, Atsushi; Terasaka, Kenichiro; Ogiwara, Kohei; Tanaka, Masayoshi Y.; Aramaki, Mitsutoshi

    2010-01-01

    Parallel ion flow velocity along a magnetic field has been measured using a laser induced fluorescence (LIF) method in an electron cyclotron resonance (ECR) argon plasma with a weakly-diverging magnetic field. To measure parallel flow velocity in a cylindrical plasma using the LIF method, the laser beam should be injected along device axis; however, the reflection of the incident beam causes interference between the LIF emission of the incident and reflected beams. Here we present a method of quasi-parallel laser injection at a small angle, which utilizes the reflected beam as well as the incident beam to obtain the parallel ion flow velocity. Using this method, we observed an increase in parallel ion flow velocity along the magnetic field. The acceleration mechanism is briefly discussed on the basis of the ion fluid model. (author)

  17. Electron microscopy study of Ni induced crystallization in amorphous Si thin films

    International Nuclear Information System (INIS)

    Radnóczi, G. Z.; Battistig, G.; Pécz, B.; Dodony, E.; Vouroutzis, N.; Stoemenos, J.; Frangis, N.; Kovács, A.

    2015-01-01

    The crystallization of amorphous silicon is studied by transmission electron microscopy. The effect of Ni on the crystallization is studied in a wide temperature range heating thinned samples in-situ inside the microscope. Two cases of limited Ni source and unlimited Ni source are studied and compared. NiSi 2 phase started to form at a temperature as low as 250°C in the limited Ni source case. In-situ observation gives a clear view on the crystallization of silicon through small NiSi 2 grain formation. The same phase is observed at the crystallization front in the unlimited Ni source case, where a second region is also observed with large grains of Ni 3 Si 2 . Low temperature experiments show, that long annealing of amorphous silicon at 410 °C already results in large crystallized Si regions due to the Ni induced crystallization

  18. Theory of current-induced spin polarization in an electron gas

    Science.gov (United States)

    Gorini, Cosimo; Maleki Sheikhabadi, Amin; Shen, Ka; Tokatly, Ilya V.; Vignale, Giovanni; Raimondi, Roberto

    2017-05-01

    We derive the Bloch equations for the spin dynamics of a two-dimensional electron gas in the presence of spin-orbit coupling. For the latter we consider both the intrinsic mechanisms of structure inversion asymmetry (Rashba) and bulk inversion asymmetry (Dresselhaus), and the extrinsic ones arising from the scattering from impurities. The derivation is based on the SU(2) gauge-field formulation of the Rashba-Dresselhaus spin-orbit coupling. Our main result is the identification of a spin-generation torque arising from Elliot-Yafet scattering, which opposes a similar term arising from Dyakonov-Perel relaxation. Such a torque, which to the best of our knowledge has gone unnoticed so far, is of basic nature, i.e., should be effective whenever Elliott-Yafet processes are present in a system with intrinsic spin-orbit coupling, irrespective of further specific details. The spin-generation torque contributes to the current-induced spin polarization (CISP), also known as inverse spin-galvanic or Edelstein effect. As a result, the behavior of the CISP turns out to be more complex than one would surmise from consideration of the internal Rashba-Dresselhaus fields alone. In particular, the symmetry of the current-induced spin polarization does not necessarily coincide with that of the internal Rashba-Dresselhaus field, and an out-of-plane component of the CISP is generally predicted, as observed in recent experiments. We also discuss the extension to the three-dimensional electron gas, which may be relevant for the interpretation of experiments in thin films.

  19. Kinetics of radiation-induced structural alterations in electron-irradiated polymer-based composites

    International Nuclear Information System (INIS)

    Zaikin, Yu.A.; Potanin, A.S.; Koztaeva, U.P.

    2002-01-01

    Complete text of publication follows. In our previous studies measurements of internal friction temperature dependence were used for characterization of thermally activated and radiation-induced structural evolution in different types of polymer-based composites. This paper supplements these measurements with kinetic studies of internal friction (IF) parameters and EPR signals in a glass-cloth epoxy-filled laminate ST-ETF after electron irradiation up to doses of 1-10 MGy. Experiment have shown that the lifetime of free radicals in this composite considerably exceeds the characteristic time of molecular structural rearrangement due to scission and cross-linking after irradiation, as determined from IF measurements. This result is explained by slow proceeding of sterically hindered disproportionation reactions that stabilize the end groups of the macro-chain disrupt during irradiation and finally fix the act of scission. A mathematical model is formulated for description of structural evolution and alterations of IF parameters in polymer-based composites during and after electron irradiation. The description is based on the track model of radiation damage in polymers and phenomenological theory of radiation-induced structural transformations. General description does not give details of radiation-chemical conversion in different structural components of composites but indicates the direction of their structural evolution. In the model considered a composite material was divided into three parts (binder, filler, and a boundary layer). It was supposed that after primary distribution of radiation energy radiation-chemical conversion proceeds independently in each of these regions. It was also suggested that all the radical reactions were of the second order. On the example of glass-cloth laminate ST-ETF it is shown that this model allows to describe alterations in composite structural characteristics during irradiation and in the course of their self-organization after

  20. Electronic cigarette aerosols and copper nanoparticles induce mitochondrial stress and promote DNA fragmentation in lung fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Lerner, Chad A.; Rutagarama, Pierrot; Ahmad, Tanveer; Sundar, Isaac K.; Elder, Alison; Rahman, Irfan, E-mail: irfan_rahman@urmc.rochester.edu

    2016-09-02

    Oxidants or nanoparticles have recently been identified as constituents of aerosols released from various styles of electronic cigarettes (E-cigs). Cells in the lung may be directly exposed to these constituents and harbor reactive properties capable of incurring acute cell injury. Our results show mitochondria are sensitive to both E-cig aerosols and aerosol containing copper nanoparticles when exposed to human lung fibroblasts (HFL-1) using an Air-Liquid Interface culture system, evident by elevated levels of mitochondrial ROS (mtROS). Increased mtROS after aerosol exposure is associated with reduced stability of OxPhos electron transport chain (ETC) complex IV subunit and nuclear DNA fragmentation. Increased levels of IL-8 and IL-6 in HFL-1 conditioned media were also observed. These findings reveal both mitochondrial, genotoxic, and inflammatory stresses are features of direct cell exposure to E-cig aerosols which are ensued by inflammatory duress, raising a concern on deleterious effect of vaping. - Graphical abstract: Oxidants and possibly reactive properties of metal particles in E-cig aerosols impart mitochondrial oxidative stress and DNA damage. These biological effects accompany inflammatory response which may raise concern regarding long term E-cig use. Mitochondria may be particularly sensitive to reactive properties of E-cig aerosols in addition to the potential for them to induce genotoxic stress by generating increased ROS. - Highlights: • Mitochondria are sensitive to both E-cig aerosols and metal nanoparticles. • Increased mtROS by E-cig aerosol is associated with disrupted mitochondrial energy. • E-cig causes nuclear DNA fragmentation. • E-cig aerosols induce pro-inflammatory response in human fibroblasts.

  1. Radiation-Induced Graft Polymerization: Gamma Radiation and Electron Beam Technology for Materials Development

    International Nuclear Information System (INIS)

    Madrid, Jordan F.; Cabalar, Patrick Jay; Lopez, Girlie Eunice; Abad, Lucille V.

    2015-01-01

    The formation of functional hybrid materials by attaching polymer chains with advantageous tailored properties to the surface of a base polymer with desirable bulk character is an attractive application of graft copolymerization. Radiation-induced graft polymerization (RIGP) has been a popular approach for surface modification of polymers because of its merits over conventional chemical processes. RIGP, which proceeds primarily via free radical polymerization process, has the advantages such as simplicity, low cost, control over process and adjustment of the materials composition and structure. RIGP can be performed using either electron beam or gamma radiation and it can be applied to both synthetic and natural polymers. These merits make RIGP a popular research topic worldwide. Moreover, the materials synthesized and produced via RIGP has found applications, and were proposed to produce continuous impact, in the fields of medicine, agriculture, pollution remediation, rare earth and valuable metals recovery, fuel cell membrane synthesis and catalysis to name a few. From 2012 our group has performed electron beam and gamma radiation-induced graft polymerization of various monomers onto polymers of natural and synthetic origins (e.g. monomers - glycidyl methacrylate, styrene, acrylonitrile, N,N-dimethylaminoethyl methacrylate; base polymers – polyethylene/polypropylene nonwoven fabric, polypropylene nonwoven fabric pineapple fibers, cellulose nonwoven fabric microcrystalline cellulose). We tested these grafted materials for heavy metals (Pb, Ni, Cu) and organic molecule removal from aqueous solutions and E. coli activity (using reversible addition fragmentation chain transfer RAFT mediated grafting). The results clearly showed the success of materials modified via FIGP in these applications. Currently, we are studying the applications of grafted materials on treatment of waste waters from tanning industry, value addition to abaca nonwoven fabrics cell sheet

  2. Real-time observation of intersystem crossing induced by charge recombination during bimolecular electron transfer reactions

    KAUST Repository

    Alsam, Amani Abdu

    2016-09-21

    Real-time probing of intersystem crossing (ISC) and triplet-state formation after photoinduced electron transfer (ET) is a particularly challenging task that can be achieved by time-resolved spectroscopy with broadband capability. Here, we examine the mechanism of charge separation (CS), charge recombination (CR) and ISC of bimolecular photoinduced electron transfer (PET) between poly[(9,9-di(3,3′-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and dicyanobenzene (DCB) using time-resolved spectroscopy. PET from PFN to DCB is confirmed by monitoring the transient absorption (TA) and infrared spectroscopic signatures for the radical ion pair (DCB─•-PFN+•). In addition, our time-resolved results clearly demonstrate that CS takes place within picoseconds followed by CR within nanoseconds. The ns-TA data exhibit the clear spectroscopic signature of PFN triplet-triplet absorption, induced by the CR of the radical ion pairs (DCB─•-PFN+•). As a result, the triplet state of PFN (3PFN*) forms and subsequently, the ground singlet state is replenished within microseconds. © 2016

  3. Transformation of methano[60]fullerenes in dihydrofullerofuranes induced by electron transfer

    International Nuclear Information System (INIS)

    Yanilkin, V.V.; Toropchina, A.V.; Morozov, V.I.; Nastapova, N.V.; Gubskaya, V.P.; Sibgatullina, F.G.; Azancheev, N.M.; Efremov, Yu.Ya.; Nuretdinov, I.A.

    2004-01-01

    The electrochemical reduction of methano[60]fullerenes (61-acetyl-61-(diethoxyphosphoryl)methano-60-fullerene 1, 61-acetyl-61-(diisopropoxyphosphoryl)methano-60-fullerene 2, 61-(2,2-diethoxyacetyl)-61-(diethoxy-phosphoryl)methano-60-fullerene 3, 61-phenyl-61-(1,2-dioxo-3,3-dimethyl-buthyl)methano-60-fullerene 4) in o-dichlorobenzene-DMF (3:1 v/v)/0.1 M Bu 4 NBF 4 on a glass-carbon electrode proceeds in a few steps. The reversible transfer of the first electron results in the formation of radical anions registered by ESR method. The subsequent reduction proceeds differently because of the various stability of anionic intermediates. The radical anions of the methanofullerenes 3 and 4 are less stable than the radical anions of compounds 1 and 2 and less stable than the radical anions of methanofullerenes, which contain an ester and/or a phosphonate group. The opening of a cyclopropane ring occurs during the stage of the formation of radical trianions of methanofullerenes 1, 2. The same process for compounds 3, 4 proceeds slowly in radical anions and fast in dianions. The opening of cyclopropane ring for all compounds is not accompanied by the elimination of methanogroup and results in the formation of dihydrofullerenofurane derivatives. The transformation of methanofullerene 3 induced by single electron transfer proceeds via a chain reaction mechanism

  4. Radiation induced coloring of glasses measured during and after electron irradiation

    International Nuclear Information System (INIS)

    Swyler, K.J.; Hardy, W.H. II; Levy, P.W.

    1975-01-01

    The growth of color centers during irradiation, and the decay after irradiation, were studied in two glasses using recently developed equipment for making optical absorption and luminescence measurements during and after electron irradiation. The glasses studied were NBS 710, a soda-lime silicate glass, and NBS 711, a lead silicate glass. Both glasses exhibit similar coloring characteristics. The radiation-induced absorption spectra consists of a weak gaussian shaped band in the visible, a stronger gaussian band in the ultraviolet, and a band edge ''shift'' which may be accurately approximated by a third gaussian band. For all absorption bands, the color center vs dose (or irradiation time) curves can be accurately resolved into two saturating exponential and one linear component. The decay curves obtained after the irradiation is terminated can be accurately expressed by three exponential components. Coloring and decay curves made at different dose rates indicate that the processes responsible for decay after irradiation and electron hole recombination during irradiation play important roles in determining the rate and extent of coloring. Results are qualitatively in agreement with some very simple kinetic treatments for color center formation. In some, but not all, respects the quantitative agreement is also good. Lastly, the results indicate that it is necessary to make measurements during irradiation to establish the formation kinetics of color centers that are unstable at the bombardment temperature. (U.S.)

  5. Electronic energy loss effects on chemical modification of polyimide induced by high energy xenon ions

    International Nuclear Information System (INIS)

    Sun Youmei; Zhu Zhiyong; Jin Yunfan; Wang Zhiguang; Hou Mingdong

    2004-01-01

    Stacked polyimide (PI) films of about 25 μm in thickness were irradiated with 1.755 GeV xenon ions under vacuum at room temperature. The chemical changes of modified PI films were studied by Fourier transform infrared (FTIR) and ultraviolet/visible (UV/Vis) absorption spectroscopy. The FTIR results show that the absorbance of the typical function groups decreases exponentially as a function of fluence. Under 8.8 keV/nm (minimum) and 11.5 keV/nm (maximum) electronic energy loss of 136 Xe irradiation, the mean degradation radius of all function groups in PI is 3.6 and 4.1 nm, respectively. The alkyne end group was found after irradiation and its formation radius was 5.6 nm and 5.9 nm corresponding to 8.8 keV/nm and 11.5 keV/nm, respectively. the UV/Vis analysis indicates the radiation induced absorbance change follows a linear relation with fluence, and the production efficiency of chromospheres depends strongly on the electronic energy loss (dE/dX) e . (authors)

  6. Quantitative Global Estimates of Lightning-Induced Electron Precipitation from the Radiation Belts

    Science.gov (United States)

    Sousa, A. P.

    2017-12-01

    Pitch-angle scattering by radio waves in the VLF ( 3-30kHz) band is thought to be a major loss mechanism for energetic radiation-belt electrons. Resonant interactions with Whistler-mode VLF waves can alter the reflection altitude of trapped electrons 100keV - 1MeV; when a particle reflects at a low enough altitude, it can be removed from the magnetosphere through collisions with ionospheric constituents. Terrestrial lightning provides a natural and constantly-occurring source of VLF waves. Here we present a three-dimensional forward model of lightning-induced electron precipitation (LEP) due to resonant pitch-angle scattering from a single lightning stroke. Previous efforts (Lauben 1998, Bortnik 2006) have used two-dimensional raytracing combined with analytical expressions of pitch-angle scattering to forward model precipitation from a single stroke as a function of input and output latitude. However, these models are limited in geospatial accuracy by their use of ideal plasmasphere and magnetic field models. We relax several model assumptions by incorporating a realistic plasmasphere parameterized by Kp, to better capture the spatial dependence of LEP. We then combine our end-to-end model of the LEP process with terrestrial lightning activity data from the GLD360 sensor network to construct a real-time geospatial model of LEP-driven energy deposition into the ionosphere. We explore global and seasonal statistics, provide precipitation estimates for maximally-and-minimally-filled conditions, and compute timescales on which a populated flux tube could be depleted by LEP alone.

  7. Low-Temperature Electron Beam-Induced Transformations of Cesium Lead Halide Perovskite Nanocrystals

    Science.gov (United States)

    2017-01-01

    Cesium lead halide perovskite (CsPbX3, with X = Br, Cl, I) nanocrystals have been found to undergo severe modifications under the high-energy electron beam irradiation of a transmission electron microscope (80/200 keV). In particular, in our previous work, together with halogen desorption, Pb2+ ions were found to be reduced to Pb0 and then diffused to form lead nanoparticles at temperatures above −40 °C. Here, we present a detailed irradiation study of CsPbBr3 nanocrystals at temperatures below −40 °C, a range in which the diffusion of Pb0 atoms/clusters is drastically suppressed. Under these conditions, the irradiation instead induces the nucleation of randomly oriented CsBr, CsPb, and PbBr2 crystalline domains. In addition to the Br desorption, which accompanies Pb2+ reduction at all the temperatures, Br is also desorbed from the CsBr and PbBr2 domains at low temperatures, leading to a more pronounced Br loss, thus the final products are mainly composed of Cs and Pb. The overall transformation involves the creation of voids, which coalesce upon further exposure, as demonstrated in both nanosheets and nanocuboids. Our results show that although low temperatures hinder the formation of Pb nanoparticles in CsPbBr3 nanocrystals when irradiated, the nanocrystals are nevertheless unstable. Consequently, we suggest that an optimum combination of temperature range, electron energy, and dose rate needs to be carefully chosen for the characterization of halide perovskite nanocrystals to minimize both the Pb nanoparticle formation and the structural decomposition. PMID:28983524

  8. Tunneling induced electron transfer in SiNx/AlGaN/GaN based metal-insulator-semiconductor structures

    International Nuclear Information System (INIS)

    Wang, M.J.; Shen, B.; Wang, Y.; Huang, S.; Xu, F.J.; Xu, J.; Qin, Z.X.; Yang, Z.J.; Zhang, G.Y.

    2007-01-01

    Tunneling induced electron transfer in SiN x /Al 0.22 Ga 0.78 N/GaN based metal-insulator-semiconductor (MIS) structures has been investigated by means of capacitance-voltage (C-V) measurements at various temperatures. Large clock-wise hysteresis window in C-V profiles indicates the injection of electrons from the two-dimensional electron gas (2DEG) channel to the SiN x layer. Depletion of the 2DEG at positive bias in the negative sweeping direction indicates that the charges injected have a long decay time, which was also observed in the recovery process of the capacitance after injection. The tunneling induced electron transfer effect in SiN x /Al 0.22 Ga 0.78 N/GaN based MIS structure opens up a way to design Al x Ga 1-x N/GaN based variable capacitors and memory devices

  9. Beam Energy Scaling of Ion-Induced Electron Yield from K+ Ions Impact on Stainless Steel Surfaces

    CERN Document Server

    Kireeff-Covo, Michel; Barnard, John J; Bieniosek, Frank; Celata, C M; Cohen, Ronald; Friedman, Alex; Grote, D P; Kwan, Joe W; Lund, Steven M; Molvik, Arthur; Seidl, Peter; Vay, Jean-Luc; Vujic, Jasmina L; Westenskow, Glen

    2005-01-01

    The cost of accelerators for heavy-ion inertial fusion energy (HIF) can be reduced by using the smallest possible clearance between the beam and the wall from the beamline. This increases beam loss to the walls, generating ion-induced electrons that could be trapped by beam space charge potential into an "electron cloud," which can cause degradation or loss of the ion beam. In order to understand the physical mechanism of production of ion-induced electrons we have measured impact of K+ ions with energies up to 400 KeV on stainless steel surfaces near grazing incidence, using the ion source test stand (STS-500) at LLNL. The electron yield will be discussed and compared with experimental measurements from 1 MeV K+ ions in the High-Current Experiment at LBNL.*

  10. Heat-induced antigen retrieval of epoxy sections for electron microscopy.

    Science.gov (United States)

    Brorson, S H

    2001-07-01

    The purpose of this manuscript is to review the literature on the use of heat-induced antigen retrieval methods to enhance the immunolabeling of epoxy sections at the electron microscopical level. The history of the development of antigen retrieval by heating formaldehyde fixed paraffin sections in a buffer solution is given in short, and how this technique has been extended to resin sections and in particular epoxy sections is explained. Theories for the mechanism of enhancement of the immunolabeling of epoxy sections by the heat-retrieval method are discussed, and it is finally speculated whether most of the mechanisms for antigen retrieval on epoxy sections in heated buffer solution are essentially the same as for conventional immunoenhancing by deplastizing and etching. The more accelerator used in the processing of the tissue the more intense the immunolabeling of the heated epoxy sections becomes. The intensity of immunolabeling of the epoxy sections increases with the temperature in the heated buffer solution, and the intensity is significantly higher at high autoclave temperatures than at 95 degrees C, Heat-induced antigen retrieval is also compared with other, conventional techniques for enhancing the immunolabeling of epoxy sections.

  11. Techniques to distinguish between electron and photon induced events using segmented germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kroeninger, K.

    2007-06-05

    Two techniques to distinguish between electron and photon induced events in germanium detectors were studied: (1) anti-coincidence requirements between the segments of segmented germanium detectors and (2) the analysis of the time structure of the detector response. An 18-fold segmented germanium prototype detector for the GERDA neutrinoless double beta-decay experiment was characterized. The rejection of photon induced events was measured for the strongest lines in {sup 60}Co, {sup 152}Eu and {sup 228}Th. An accompanying Monte Carlo simulation was performed and the results were compared to data. An overall agreement with deviations of the order of 5-10% was obtained. The expected background index of the GERDA experiment was estimated. The sensitivity of the GERDA experiment was determined. Special statistical tools were developed to correctly treat the small number of events expected. The GERDA experiment uses a cryogenic liquid as the operational medium for the germanium detectors. It was shown that germanium detectors can be reliably operated through several cooling cycles. (orig.)

  12. In situ growth optimization in focused electron-beam induced deposition

    Directory of Open Access Journals (Sweden)

    Paul M. Weirich

    2013-12-01

    Full Text Available We present the application of an evolutionary genetic algorithm for the in situ optimization of nanostructures that are prepared by focused electron-beam-induced deposition (FEBID. It allows us to tune the properties of the deposits towards the highest conductivity by using the time gradient of the measured in situ rate of change of conductance as the fitness parameter for the algorithm. The effectiveness of the procedure is presented for the precursor W(CO6 as well as for post-treatment of Pt–C deposits, which were obtained by the dissociation of MeCpPt(Me3. For W(CO6-based structures an increase of conductivity by one order of magnitude can be achieved, whereas the effect for MeCpPt(Me3 is largely suppressed. The presented technique can be applied to all beam-induced deposition processes and has great potential for a further optimization or tuning of parameters for nanostructures that are prepared by FEBID or related techniques.

  13. Study on Nanostructures Induced by High-Current Pulsed Electron Beam

    Directory of Open Access Journals (Sweden)

    Bo Gao

    2012-01-01

    Full Text Available Four techniques using high-current pulsed electron beam (HCPEB were proposed to obtain surface nanostructure of metal and alloys. The first method involves the distribution of several fine Mg nanoparticles on the top surface of treated samples by evaporation of pure Mg with low boiling point. The second technique uses superfast heating, melting, and cooling induced by HCPEB irradiation to refine the primary phase or the second phase in alloys to nanosized uniform distributed phases in the matrix, such as the quasicrystal phase Mg30Zn60Y10 in the quasicrystal alloy Mg67Zn30Y3. The third technique involves the refinement of eutectic silicon phase in hypereutectic Al-15Si alloys to fine particles with the size of several nanometers through solid solution and precipitation refinement. Finally, in the deformation zone induced by HCPEB irradiation, the grain size can be refined to several hundred nanometers, such as the grain size of the hypereutectic Al-15Si alloys in the deformation zone, which can reach ~400 nm after HCPEB treatment for 25 pulses. Therefore, HCPEB technology is an efficient way to obtain surface nanostructure.

  14. Electron induced conformational changes of an imine-based molecular switch on a Au(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Lotze, Christian; Henningsen, Nils; Franke, Katharina; Schulze, Gunnar; Pascual, Jose Ignacio [Inst. f. Experimentalphysik, Freie Universitaet Berlin (Germany); Luo, Ying; Haag, Rainer [Inst. f. Organische Chemie, Freie Universitaet Berlin (Germany)

    2009-07-01

    Azobenzene-based molecules exhibit a cis-trans configurational photoisomerisation in solution. Recently, the adsorption properties of azobenzene derivatives have been investigated on different metal surfaces in order to explore the possible changes in the film properties induced by external stimuli. In azobenzene, the diazo-bridge is a key group for the isomerization process. Its interaction with a metal surface is dominated through the N lone-pair electrons, which reduces the efficiency of the conformational change. In order to reduce the molecule-surface interaction, we explore an alternative molecular architecture by substituting the diazo-bridge (-N=N-) of azobenzene by an imine-group (-N=CH-). We have investigated the imine-based compound para-carboxyl-di-benzene-imine (PCI) adsorbed on a Au(111) surface. The carboxylic terminations mediates the formation of strongly bonded molecular dimers, which align in ordered rows preferentially following the fcc regions of the Au(111) herringbone reconstruction. Low temperature scanning tunneling microscopy was used to induce conformational changes between trans and cis state of individual molecules in a molecular monolayer.

  15. Electron beam induced cationic polymerization of epoxy resins. Dependence of Tg on conversion

    International Nuclear Information System (INIS)

    Degrand, H.; Cazaux, F.; Coqueret, X.

    2002-01-01

    Complete text of publication follows. The high-energy radiation curing of monomer blends polymerizing by a free radical or by a cationic mechanism receives increasing attention in the perspective of high performance composite materials. In the present work, we have focused our attention on epoxy formulations as models of the matrices polymerizing by a cationic mechanism that could be used in fiber-reinforced composites for aerospace applications. We have examined the progress of the electron beam (EB) induced polymerization of diglycidylether of bisphenol A (DGEBA) in the presence of a diaryliodonium salt (DAIS) by FTIR spectroscopy and by dynamic mechanical thermal analysis (DMA). The obtained results allow to draw the gradual increase of the temperature for the network thermomechanical transition (T a , associated with the glass transition temperature T g ) over a broad range of conversion (p) and reveal a peculiar behavior at high conversion. In this domain (p > 0.90), the material's T g is shown to decrease when conversion approaches unity. Moreover, the post-irradiation thermal treatment of the materials, that generally yields effective 'dark curing', appears to induce a decrease of T g , with an amplitude correlated with the amount of DAIS in the formulation. Owing to the particular nature of the propagating centers in cationic polymerisation, the thermal relaxation of ionic clusters trapped in the glassy matrix can be reasonably invoked as a possible cause for this behavior

  16. Microscopic kinetic analysis of space-charge induced optical microbunching in a relativistic electron beam

    Directory of Open Access Journals (Sweden)

    Agostino Marinelli

    2010-11-01

    Full Text Available Longitudinal space-charge forces from density fluctuations generated by shot noise can be a major source of microbunching instability in relativistic high brightness electron beams. The gain in microbunching due to this effect is broadband, extending at least up to optical frequencies, where the induced structure on the beam distribution gives rise to effects such as coherent optical transition radiation. In the high-frequency regime, theoretical and computational analyses of microbunching formation require a full three-dimensional treatment. In this paper we address the problem of space-charge induced optical microbunching formation in the high-frequency limit when transverse thermal motion due to finite emittance is included for the first time. We derive an analytical description of this process based on the beam’s plasma dielectric function. We discuss the effect of transverse temperature on the angular distribution of microbunching gain and its connection to the physics of Landau damping in longitudinal plasma oscillations. Application of the theory to a relevant experimental scenario is discussed. The analytical results obtained are then compared to the predictions arising from high resolution three-dimensional molecular dynamics simulations.

  17. Electron transfer-induced four-membered cyclic intermediate formation: Olefin cross-coupling vs. olefin cross-metathesis

    International Nuclear Information System (INIS)

    Okada, Yohei; Chiba, Kazuhiro

    2011-01-01

    An electron transfer-induced four-membered cyclic intermediate, formed between a radical cation of an enol ether and an unactivated olefin, played a key role in the pathway toward either cross-coupling or cross-metathesis. The presence of an alkoxy group on the phenyl ring of the olefin entirely determined the synthetic outcome of the reaction, which mirrored the efficiency of the intramolecular electron transfer.

  18. Fried-Yennie gauge recalculation of the electron line induced radiative-recoil corrections to muonium hyperfine splitting

    International Nuclear Information System (INIS)

    Brook, V.Yu.; Eides, M.I.; Karshenboim, S.G.; Shelyuto, V.A.

    1989-01-01

    A new analytic calculation of radiative-recoil corrections to muonium ground-state hyperfine splitting induced by electron line insertions is performed. The starting point of this calculation is presented by the Fried-Yennie gauge expression for the electron line factor. The final result confirms the one obtained previously from the apparently different expression in the Feynman gauge and removes the slight discrepancy which existed in the literature between the calculations in different gauges. (orig.)

  19. High energy resolution and first time-dependent positron annihilation induced Auger electron spectroscopty

    International Nuclear Information System (INIS)

    Mayer, Jakob

    2010-01-01

    It was the aim of this thesis to improve the existing positron annihilation induced Auger spectrometer at the highly intense positron source NEPOMUC (NEutron induced POsitron source MUniCh) in several ways: Firstly, the measurement time for a single spectrum should be reduced from typically 12 h to roughly 1 h or even less. Secondly, the energy resolution, which amounted to ΔE/E∼10%, should be increased by at least one order of magnitude in order to make high resolution positron annihilation induced Auger spectroscopy (PAES)-measurements of Auger transitions possible and thus deliver more information about the nature of the Auger process. In order to achieve these objectives, the PAES spectrometer was equipped with a new electron energy analyzer. For its ideal operation all other components of the Auger analysis chamber had to be adapted. Particularly the sample manipulation and the positron beam guidance had to be renewed. Simulations with SIMION registered ensured the optimal positron lens parameters. After the adjustment of the new analyzer and its components, first measurements illustrated the improved performance of the PAES setup: Firstly, the measurement time for short overview measurements was reduced from 3 h to 420 s. The measurement time for more detailed Auger spectra was shortened from 12 h to 80 min. Secondly, even with the reduced measurement time, the signal to noise ratio was also enhanced by one order of magnitude. Finally, the energy resolution was improved to ΔE/E 2,3 VV-transition with PAES. Thus, within this thesis two objectives were achieved: Firstly, the PAES spectrometer was renewed and improved by at least one order of magnitude with respect to the signal to noise ratio, the measurement time and the energy resolution. Secondly, several measurements have been carried out, demonstrating the high performance of the spectrometer. Amongst them are first dynamic PAES measurements and a high resolution measurement of the CuM 2,3 VV

  20. Electronic cigarette aerosols suppress cellular antioxidant defenses and induce significant oxidative DNA damage.

    Directory of Open Access Journals (Sweden)

    Vengatesh Ganapathy

    Full Text Available Electronic cigarette (EC aerosols contain unique compounds in addition to toxicants and carcinogens traditionally found in tobacco smoke. Studies are warranted to understand the public health risks of ECs.The aim of this study was to determine the genotoxicity and the mechanisms induced by EC aerosol extracts on human oral and lung epithelial cells.Cells were exposed to EC aerosol or mainstream smoke extracts and DNA damage was measured using the primer anchored DNA damage detection assay (q-PADDA and 8-oxo-dG ELISA assay. Cell viability, reactive oxygen species (ROS and total antioxidant capacity (TAC were measured using standard methods. mRNA and protein expression were evaluated by RT-PCR and western blot, respectively.EC aerosol extracts induced DNA damage in a dose-dependent manner, but independently of nicotine concentration. Overall, EC aerosol extracts induced significantly less DNA damage than mainstream smoke extracts, as measured by q-PADDA. However, the levels of oxidative DNA damage, as indicated by the presence of 8-oxo-dG, a highly mutagenic DNA lesion, were similar or slightly higher after exposure to EC aerosol compared to mainstream smoke extracts. Mechanistically, while exposure to EC extracts significantly increased ROS, it decreased TAC as well as the expression of 8-oxoguanine DNA glycosylase (OGG1, an enzyme essential for the removal of oxidative DNA damage.Exposure to EC aerosol extracts suppressed the cellular antioxidant defenses and led to significant DNA damage. These findings emphasize the urgent need to investigate the potential long-term cancer risk of exposure to EC aerosol for vapers and the general public.

  1. Electron-beam induced RAFT-graft polymerization of poly(acrylic acid) onto PVDF

    International Nuclear Information System (INIS)

    Grasselli, M.; Betz, N.

    2005-01-01

    This paper explores for the first time the post-radiation-induced-graft polymerization on solid substrate using reversible addition-fragmentation transfer (RAFT) mechanism. Radiation-induced graft polymerization onto polymers is a potentially interesting technique to create easily new materials from highly resistant polymers, e.g. surface graft polymerization of acrylic acid (AA) onto poly(vinylidene difluoride) (PVDF) improves its surface properties without losing its excellent mechanical properties. As a consequence of the radical nature of the polymerization processes it is difficult to control molecular weight of grafted chains, and therefore design and standardize the properties of the final product. RAFT polymerization is a suitable method to obtain monodisperse polymers. The ability of the RAFT agents to control the polymer chain length could be an interesting approach to improve the grafted polymers obtained by post-radiation-induced-graft polymerization technique. In this way, graft polymerization of AA onto electron-beam irradiated α-PVDF was performed using trithiocarbonic acid bis(1-phenylethyl) ester as a RAFT agent to control the radical polymerization. We studied several grafting parameters such as solvent, monomer concentration and grafting time in order to achieve a poly(acrylic acid) (PAA) layer onto PVDF surface. Acetic acid was found to be the best solvent for many reasons, as to drive graft polymerization mainly to the polymer surface, complete solubility and stability of all reactants. Hydrolysis of PAA chains was also studied in order to remove the trithiocarbonate functionality from the grafted polymer. A mild chemical condition was achieved in order to have thiol groups that were detected onto the modified PVDF by specific enzymatic reaction

  2. Calculation of induced current densities for humans by magnetic fields from electronic article surveillance devices

    Science.gov (United States)

    Gandhi, Om P.; Kang, Gang

    2001-11-01

    This paper illustrates the use of the impedance method to calculate the electric fields and current densities induced in millimetre resolution anatomic models of the human body, namely an adult and 10- and 5-year-old children, for exposure to nonuniform magnetic fields typical of two assumed but representative electronic article surveillance (EAS) devices at 1 and 30 kHz, respectively. The devices assumed for the calculations are a solenoid type magnetic deactivator used at store checkouts and a pass-by panel-type EAS system consisting of two overlapping rectangular current-carrying coils used at entry and exit from a store. The impedance method code is modified to obtain induced current densities averaged over a cross section of 1 cm2 perpendicular to the direction of induced currents. This is done to compare the peak current densities with the limits or the basic restrictions given in the ICNIRP safety guidelines. Because of the stronger magnetic fields at lower heights for both the assumed devices, the peak 1 cm2 area-averaged current densities for the CNS tissues such as the brain and the spinal cord are increasingly larger for smaller models and are the highest for the model of the 5-year-old child. For both the EAS devices, the maximum 1 cm2 area-averaged current densities for the brain of the model of the adult are lower than the ICNIRP safety guideline, but may approach or exceed the ICNIRP basic restrictions for models of 10- and 5-year-old children if sufficiently strong magnetic fields are used.

  3. Antigenotoxic potential of Asparagus racemosus root extract against electron beam radiation induced micronuclei formation in Swiss albino mice

    International Nuclear Information System (INIS)

    Bhandary, B. Satheesh Kumar; Sharmila, K.P.; Suchetha Kumari, N.; Bhat, Vadish S.; Shetty, Jayaram; Peter, Alex John; Jose, Jerish M.; Fernandes, Ronald

    2016-01-01

    To evaluate the antigenotoxic potential of Asparagus Racemosus Root ethanolic extract (ARE) against electron beam radiation induced micronuclei formation in Swiss albino mice. Micronucleus assay was performed in the bone marrow of Swiss albino mice according to the method of Hosseinimehr et al., 2003. The experimental animals were orally administered 200 mg/kg body weight of ARE once daily for 15 consecutive days. At the end of experimental period, the animals were euthanized and the bone marrow was collected from the femur. Control (C), Radiation control (RC) and drug control (DC) group was also maintained. The number of radiation induced Micronucleated Polychromatic Erythrocytes (MnPCE) and Micronucleated Normochromatic Erythrocytes were decreased in the ARE treated mice which was statistically significant (p<0.05) compared to radiation control group. Present findings demonstrate the antigenotoxic potential of ARE against electron beam radiation induced micronuclei formation which may be attributed to scavenging of radiation-induced free radicals

  4. High energy resolution and first time-dependent positron annihilation induced Auger electron spectroscopty

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Jakob

    2010-04-03

    It was the aim of this thesis to improve the existing positron annihilation induced Auger spectrometer at the highly intense positron source NEPOMUC (NEutron induced POsitron source MUniCh) in several ways: Firstly, the measurement time for a single spectrum should be reduced from typically 12 h to roughly 1 h or even less. Secondly, the energy resolution, which amounted to {delta}E/E{approx}10%, should be increased by at least one order of magnitude in order to make high resolution positron annihilation induced Auger spectroscopy (PAES)-measurements of Auger transitions possible and thus deliver more information about the nature of the Auger process. In order to achieve these objectives, the PAES spectrometer was equipped with a new electron energy analyzer. For its ideal operation all other components of the Auger analysis chamber had to be adapted. Particularly the sample manipulation and the positron beam guidance had to be renewed. Simulations with SIMION {sup registered} ensured the optimal positron lens parameters. After the adjustment of the new analyzer and its components, first measurements illustrated the improved performance of the PAES setup: Firstly, the measurement time for short overview measurements was reduced from 3 h to 420 s. The measurement time for more detailed Auger spectra was shortened from 12 h to 80 min. Secondly, even with the reduced measurement time, the signal to noise ratio was also enhanced by one order of magnitude. Finally, the energy resolution was improved to {delta}E/E < 1. The exceptional surface sensitivity and elemental selectivity of PAES was demonstrated in measurements of Pd and Fe, both coated with Cu layers of varying thickness. PAES showed that with 0.96 monolayer of Cu on Fe, more than 55% of the detected Auger electrons stem from Cu. In the case of the Cu coated Pd sample 0.96 monolayer of Cu resulted in a Cu Auger fraction of more than 30% with PAES and less than 5% with electron induced Auger spectroscopy

  5. Electron-beam-assisted oxygen purification at low temperatures for electron-beam-induced pt deposits: towards pure and high-fidelity nanostructures.

    Science.gov (United States)

    Plank, Harald; Noh, Joo Hyon; Fowlkes, Jason D; Lester, Kevin; Lewis, Brett B; Rack, Philip D

    2014-01-22

    Nanoscale metal deposits written directly by electron-beam-induced deposition, or EBID, are typically contaminated because of the incomplete removal of the original organometallic precursor. This has greatly limited the applicability of EBID materials synthesis, constraining the otherwise powerful direct-write synthesis paradigm. We demonstrate a low-temperature purification method in which platinum-carbon nanostructures deposited from MeCpPtIVMe3 are purified by the presence of oxygen gas during a post-electron exposure treatment. Deposit thickness, oxygen pressure, and oxygen temperature studies suggest that the dominant mechanism is the electron-stimulated reaction of oxygen molecules adsorbed at the defective deposit surface. Notably, pure platinum deposits with low resistivity and retain the original deposit fidelity were accomplished at an oxygen temperature of only 50 °C.

  6. Overscreening-underscreening transition in the two-channel Kondo model induced by electron-electron repulsion

    International Nuclear Information System (INIS)

    Zhang Yumei; Chen Hong.

    1995-09-01

    The effects of the repulsion between the electrons on the two-channel Kondo problem are studied by use of the bosonization technique. Following Emery and Kivelson, we define a special case in the spin density wave sector, in which the impurity spin is actually detached from the dynamics of the electrons. The model is thus mapped to a local Sine-Gordon system. For weak repulsion, the basic features of the overscreening picture are maintained. However, at sufficient strong repulsion the system is driven into the weak coupling regime, hence an overscreening-underscreening transition emerges. (author). 22 refs

  7. Fabrication of FeSi and Fe{sub 3}Si compounds by electron beam induced mixing of [Fe/Si]{sub 2} and [Fe{sub 3}/Si]{sub 2} multilayers grown by focused electron beam induced deposition

    Energy Technology Data Exchange (ETDEWEB)

    Porrati, F.; Sachser, R.; Huth, M. [Physikalisches Institut, Goethe-Universität, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Gazzadi, G. C. [S3 Center, Nanoscience Institute-CNR, Via Campi 213/a, 41125 Modena (Italy); Frabboni, S. [S3 Center, Nanoscience Institute-CNR, Via Campi 213/a, 41125 Modena (Italy); FIM Department, University of Modena and Reggio Emilia, Via G. Campi 213/a, 41125 Modena (Italy)

    2016-06-21

    Fe-Si binary compounds have been fabricated by focused electron beam induced deposition by the alternating use of iron pentacarbonyl, Fe(CO){sub 5}, and neopentasilane, Si{sub 5}H{sub 12} as precursor gases. The fabrication procedure consisted in preparing multilayer structures which were treated by low-energy electron irradiation and annealing to induce atomic species intermixing. In this way, we are able to fabricate FeSi and Fe{sub 3}Si binary compounds from [Fe/Si]{sub 2} and [Fe{sub 3}/Si]{sub 2} multilayers, as shown by transmission electron microscopy investigations. This fabrication procedure is useful to obtain nanostructured binary alloys from precursors which compete for adsorption sites during growth and, therefore, cannot be used simultaneously.

  8. In Situ Transmission Electron Microscopy Study of Electron Beam-Induced Transformations in Colloidal Cesium Lead Halide Perovskite Nanocrystals

    Science.gov (United States)

    2017-01-01

    An increasing number of studies have recently reported the rapid degradation of hybrid and all-inorganic lead halide perovskite nanocrystals under electron beam irradiation in the transmission electron microscope, with the formation of nanometer size, high contrast particles. The nature of these nanoparticles and the involved transformations in the perovskite nanocrystals are still a matter of debate. Herein, we have studied the effects of high energy (80/200 keV) electron irradiation on colloidal cesium lead bromide (CsPbBr3) nanocrystals with different shapes and sizes, especially 3 nm thick nanosheets, a morphology that facilitated the analysis of the various ongoing processes. Our results show that the CsPbBr3 nanocrystals undergo a radiolysis process, with electron stimulated desorption of a fraction of bromine atoms and the reduction of a fraction of Pb2+ ions to Pb0. Subsequently Pb0 atoms diffuse and aggregate, giving rise to the high contrast particles, as previously reported by various groups. The diffusion is facilitated by both high temperature and electron beam irradiation. The early stage Pb nanoparticles are epitaxially bound to the parent CsPbBr3 lattice, and evolve into nonepitaxially bound Pb crystals upon further irradiation, leading to local amorphization and consequent dismantling of the CsPbBr3 lattice. The comparison among CsPbBr3 nanocrystals with various shapes and sizes evidences that the damage is particularly pronounced at the corners and edges of the surface, due to a lower diffusion barrier for Pb0 on the surface than inside the crystal and the presence of a larger fraction of under-coordinated atoms. PMID:28122188

  9. Head-tail instability caused by electron cloud in positron storage rings

    CERN Document Server

    Ohmi, K

    2000-01-01

    In positron or proton storage rings with many closely spaced bunches, a large number of electrons can be generated in the vacuum chamber due to photoemission or secondary emission. The density of this `electron cloud' increases along a bunch train, until the growth saturates under the influence of its own space charge field. In this report, we discuss the possibility of a single-bunch two-stream instability driven by the electron cloud, where any initial head-tail perturbation of the bunch is amplified by the coherent motion of cloud electrons near the beam. Depending on the strength of the beam-electron interaction, the chromaticity and the synchrotron oscillation frequency, this instability either resembles a linac beam break up, or a head-tail instability. We present computer simulations of beam break up and head-tail instabilities for the Low Energy Ring of the KEK B factory, and compare the simulation results with analytical estimates.

  10. Evidence for the enhancement of stress-induced ordering in Ag-27 at % Zn alloy due to electron irradiation

    International Nuclear Information System (INIS)

    Halbwachs, M.; Hillairet, J.

    1975-01-01

    Internal friction measurements of rate of stress-induced ordering in a silver-zinc alloy during bombardment by electrons are reported. This alloy exhibits a Zener relaxation, i.e. a change in the degree of order with a change in the applied stress, and the rate of relaxation can provide information concerning the enhancement of the rate of ordering [fr

  11. Creation of High Mobility Two-Dimensional Electron Gases via Strain Induced Polarization at an Otherwise Nonpolar Complex Oxide Interface

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Trier, Felix; Kasama, Takeshi

    2015-01-01

    The discovery of two-dimensional electron gases (2DEGs) in SrTiO3-based heterostructures provides new opportunities for nanoelectronics. Herein, we create a new type of oxide 2DEG by the epitaxial-strain-induced polarization at an otherwise nonpolar perovskite-type interface of CaZrO3/SrTiO3. Rem...

  12. The radiation-induced topotactic conversion of di-para anthracene to anthracene: an electron microscopic study

    International Nuclear Information System (INIS)

    Parkinson, G.M.; Goringe, M.J.; Thomas, J.M.

    1977-01-01

    A study was made of single crystals of di-para anthracene, the product of photodimerisation of anthracene. This undergoes an electron-induced topotactic conversion to anthracene, and the study of this reaction using low temperature TEM enabled the identification of separate stages in the conversion and the elucidation of probable mechanistic routes. (author)

  13. Nitrogen plasma formation through terahertz-induced ultrafast electron field emission

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Zalkovskij, Maksim; Strikwerda, Andrew

    2015-01-01

    Electron microscopy and electron diffraction techniques rely on electron sources. Those sources require strong electric fields to extract electrons from metals, either by the photoelectric effect, driven by multiphoton absorption of strong laser fields, or in the static field emission regime...

  14. Methylene Blue Ameliorates Ischemia/Reperfusion-Induced Cerebral Edema: An MRI and Transmission Electron Microscope Study.

    Science.gov (United States)

    Fang, Qing; Yan, Xu; Li, Shaowu; Sun, Yilin; Xu, Lixin; Shi, Zhongfang; Wu, Min; Lu, Yi; Dong, Liping; Liu, Ran; Yuan, Fang; Yang, Shao-Hua

    2016-01-01

    The neuroprotective effect of methylene blue (MB) has been identified against various brain disorders, including ischemic stroke. In the present study, we evaluated the effects of MB on postischemic brain edema using magnetic resonance imaging (MRI) and transmission electron microscopy (TEM). Adult male rats were subjected to transient focal cerebral ischemia induced by 1 h middle cerebral artery occlusion (MCAO), followed by reperfusion. MB was infused intravenously immediately after reperfusion (3 mg/kg) and again at 3 h post-occlusion (1.5 mg/kg). Normal saline was administered as vehicle control. Sequential MRIs, including apparent diffusion coefficient (ADC) and T2-weighted imaging (T2WI), were obtained at 0.5, 2.5, and 48 h after the onset of stroke. Separated groups of animals were sacrificed at 2.5 and 48 h after stroke for ultrastructural analysis by TEM. In addition, final lesion volumes were analyzed by triphenyltetrazolium chloride (TTC) staining at 48 h after stroke. Ischemic stroke induced ADC lesion volume at 0.5 h during MCAOs that were temporally recovered at 1.5 h after reperfusion. No significant difference in ADC-defined lesion was observed between vehicle and MB treatment groups. At 48 h after stroke, MB significantly reduced ADC lesion and T2WI lesion volume and attenuated cerebral swelling. Consistently, MB treatment significantly decreased TTC-defined lesion volume at 48 h after stroke. TEM revealed remarkable swollen astrocytes, astrocytic perivascular end-feet, and concurrent shrunken neurons in the penumbra at 2.5 and 48 h after MCAO. MB treatment attenuated astrocyte swelling, the perivascular astrocytic foot process, and endothelium and also alleviated neuron degeneration. This study demonstrated that MB could decrease postischemic brain edema and provided additional evidence that future clinical investigation of MB for the treatment of ischemic stroke is warrented.

  15. Electron-beam-induced post-grafting polymerization of acrylic acid onto the surface of Kevlar fibers

    Science.gov (United States)

    Xu, Lu; Hu, Jiangtao; Ma, Hongjuan; Wu, Guozhong

    2018-04-01

    The surface of Kevlar fibers was successfully modified by electron beam (EB)-induced post-grafting of acrylic acid (AA). The generation of radicals in the fibers was confirmed by electron spin resonance (ESR) measurements, and the concentration of radicals was shown to increase as the absorbed dose increased, but decrease with increasing temperature. The influence of the synthesis conditions on the degree of grafting was also investigated. The surface microstructure and chemical composition of the modified Kevlar fibers were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The SEM images revealed that the surface of the grafted fibers was rougher than those of the pristine and irradiated fibers. XPS analysis confirmed an increase in C(O)OH groups on the surface of the Kevlar fibers, suggesting successful grafting of AA. These results indicate that EB-induced post-grafting polymerization is effective for modifying the surface properties of Kevlar fibers.

  16. Electron-spin-resonance study of radiation-induced paramagnetic defects in oxides grown on (100) silicon substrates

    International Nuclear Information System (INIS)

    Kim, Y.Y.; Lenahan, P.M.

    1988-01-01

    We have used electron-spin resonance to investigate radiation-induced point defects in Si/SiO 2 structures with (100) silicon substrates. We find that the radiation-induced point defects are quite similar to defects generated in Si/SiO 2 structures grown on (111) silicon substrates. In both cases, an oxygen-deficient silicon center, the E' defect, appears to be responsible for trapped positive charge. In both cases trivalent silicon (P/sub b/ centers) defects are primarily responsible for radiation-induced interface states. In earlier electron-spin-resonance studies of unirradiated (100) substrate capacitors two types of P/sub b/ centers were observed; in oxides prepared in three different ways only one of these centers, the P/sub b/ 0 defect, is generated in large numbers by ionizing radiation

  17. Evaluation of induced radioactivity in 10 MeV-electron irradiated spices, (1); [gamma]-ray measurement

    Energy Technology Data Exchange (ETDEWEB)

    Furuta, Masakazu; Katayama, Tadashi; Ito, Norio; Mizohata, Akira; Matsunami, Tadao; Shibata, Setsuko; Toratani, Hirokazu (Osaka Prefectural Univ., Sakai (Japan). Research Inst. for Advanced Science and Technology); Takeda, Atsuhiko

    1994-02-01

    Black pepper, white pepper, red pepper, ginger and turmeric were irradiated with 10 MeV electrons from a linear accelerator to a dose of 100 kGy and radioactivity was measured in order to estimate induced radioactivity in the irradiated foods. Induced radioactivity could not be detected significantly by [gamma]-ray spectrometry in the irradiated samples except for spiked samples which contain some photonuclear target nuclides in the list of photonuclear reactions which could produce radioactivity below 10 MeV. From the amount of observed radioactivities of short-lived photonuclear products in the spiked samples and calculation of H[sub 50] according to ICRP Publication 30, it was concluded that the induced radioactivity and its biological effects in the 10 MeV electron-irradiated natural samples were negligible in comparison with natural radioactivity from [sup 40]K contained in the samples. (author).

  18. Reconstruction of Laser-Induced Surface Topography from Electron Backscatter Diffraction Patterns.

    Science.gov (United States)

    Callahan, Patrick G; Echlin, McLean P; Pollock, Tresa M; De Graef, Marc

    2017-08-01

    We demonstrate that the surface topography of a sample can be reconstructed from electron backscatter diffraction (EBSD) patterns collected with a commercial EBSD system. This technique combines the location of the maximum background intensity with a correction from Monte Carlo simulations to determine the local surface normals at each point in an EBSD scan. A surface height map is then reconstructed from the local surface normals. In this study, a Ni sample was machined with a femtosecond laser, which causes the formation of a laser-induced periodic surface structure (LIPSS). The topography of the LIPSS was analyzed using atomic force microscopy (AFM) and reconstructions from EBSD patterns collected at 5 and 20 kV. The LIPSS consisted of a combination of low frequency waviness due to curtaining and high frequency ridges. The morphology of the reconstructed low frequency waviness and high frequency ridges matched the AFM data. The reconstruction technique does not require any modification to existing EBSD systems and so can be particularly useful for measuring topography and its evolution during in situ experiments.

  19. SEPERATION OF IKONOS SENSOR’S ELECTRONIC NOISE FROM ATMOSPHERIC INDUCED EFFECTS

    Directory of Open Access Journals (Sweden)

    M. R. Mobashery

    2013-09-01

    Full Text Available The quality of satellite images has always been of particular importance in remote sensing. Signals received from satellite sensors include some signals other than those of target signal that may be classified totally as the atmospheric effect and the sensor induced noise. Separating non-target signals and attempting in removing them from images is essential. One method for measuring and removing non-target signals is that of atmospheric correction by Dark Object Subtraction (DOS. This method is based on the sensor’s output for the targets that should have almost zero reflectance in a given band. Next, the obtained value will be deducted from the remaining pixels values; regardless of the type of the sensors. Each Charge-Coupled Device (CCD has its own noise behavior; therefore, the amount deducted values from each pixel can be different for each CCD unit and type. Among the various noises of the CCD and their related electronic circuits, dark current noise, non-uniform pixels noise and read noise were selected to be studied in this paper. The data were obtained from multispectral sensor images of IKONOS. This sensor can provide images in two forms of Panchromatic (PAN and Multispectral (MS. The results of this study showed that the amount of dark object pixels and the total amount of CCD noises in each band are different. Separation of the noises introduced in this paper from the amount of dark object pixel values can result in an upgraded method for image atmosphere corrections.

  20. An electron induced two-dimensional switch made of azobenzene derivatives anchored in supramolecular assemblies.

    Science.gov (United States)

    Henzl, Jörg; Morgenstern, Karina

    2010-06-21

    Supramolecular assemblies of 4-anilino-4'-nitroazobenzene are investigated on the Au(111) surface by low temperature scanning tunneling microscopy and spectroscopy with submolecular resolution. Adsorption at 250 K leads to three different structures that are formed via hydrogen bonds: a star structure and two types of line structures: a meandering and a zigzag line. The formation of these supramolecular assemblies is affected by the available space on the fcc domains of the reconstructed Au(111) substrate as well as by the two-dimensional chirality of the molecules on the surface. The star structure is enantiomerically pure, while both types of lines consist of a racemic mixture. Bonding between homochiral pairs differ from the one between heterochiral pairs in the position of the hydrogen bonds. Inside these supramolecular assemblies two configurations of the molecules are identified: An almost straight trans-configuration and a slightly bent cis*-configuration. The trans-configuration largely reflects the structure of this isomer in gas phase, while the cis*-configuration is two-dimensional on the surface in contrast to the three-dimensional gas phase cis-configuration. The reversible trans-cis* isomerization is induced by electron tunneling through the LUMO+1 state of the molecule, which is located at +2.9 V.

  1. Laser-Induced Graphene by Multiple Lasing: Toward Electronics on Cloth, Paper, and Food.

    Science.gov (United States)

    Chyan, Yieu; Ye, Ruquan; Li, Yilun; Singh, Swatantra Pratap; Arnusch, Christopher J; Tour, James M

    2018-03-27

    A simple and facile method for obtaining patterned graphene under ambient conditions on the surface of diverse materials ranging from renewable precursors such as food, cloth, paper, and cardboard to high-performance polymers like Kevlar or even on natural coal would be highly desirable. Here, we report a method of using multiple pulsed-laser scribing to convert a wide range of substrates into laser-induced graphene (LIG). With the increased versatility of the multiple lase process, highly conductive patterns can be achieved on the surface of a diverse number of substrates in ambient atmosphere. The use of a defocus method results in multiple lases in a single pass of the laser, further simplifying the procedure. This method can be implemented without increasing processing times when compared with laser induction of graphene on polyimide (Kapton) substrates as previously reported. In fact, any carbon precursor that can be converted into amorphous carbon can be converted into graphene using this multiple lase method. This may be a generally applicable technique for forming graphene on diverse substrates in applications such as flexible or even biodegradable and edible electronics.

  2. Electron Beam-Induced Deposition for Atom Probe Tomography Specimen Capping Layers.

    Science.gov (United States)

    Diercks, David R; Gorman, Brian P; Mulders, Johannes J L

    2017-04-01

    Six precursors were evaluated for use as in situ electron beam-induced deposition capping layers in the preparation of atom probe tomography specimens with a focus on near-surface features where some of the deposition is retained at the specimen apex. Specimens were prepared by deposition of each precursor onto silicon posts and shaped into sub-70-nm radii needles using a focused ion beam. The utility of the depositions was assessed using several criteria including composition and uniformity, evaporation behavior and evaporation fields, and depth of Ga+ ion penetration. Atom probe analyses through depositions of methyl cyclopentadienyl platinum trimethyl, palladium hexafluoroacetylacetonate, and dimethyl-gold-acetylacetonate [Me2Au(acac)] were all found to result in tip fracture at voltages exceeding 3 kV. Examination of the deposition using Me2Au(acac) plus flowing O2 was inconclusive due to evaporation of surface silicon from below the deposition under all analysis conditions. Dicobalt octacarbonyl [Co2(CO)8] and diiron nonacarbonyl [Fe2(CO)9] depositions were found to be effective as in situ capping materials for the silicon specimens. Their very different evaporation fields [36 V/nm for Co2(CO)8 and 21 V/nm for Fe2(CO)9] provide options for achieving reasonably close matching of the evaporation field between the capping material and many materials of interest.

  3. Resonant antineutrino induced electron capture with low energy bound-beta beams

    Energy Technology Data Exchange (ETDEWEB)

    Oldeman, R.G.C.; Meloni, M.; Saitta, B. [Universita degli Studi di Cagliari (Italy); INFN, Sezione di Cagliari, Dipartimento di Fisica, Cagliari (Italy)

    2010-01-15

    Antineutrino induced electron capture is a resonant process that can have a large cross-section for beams of monochromatic antineutrinos. We calculate the cross-section of this process and investigate an experimental setup where monochromatic antineutrinos are produced from the bound-beta decay of fully ionized radioactive atoms in a storage ring. If the energy between the source and the target is well matched, the cross-sections can be significantly larger than the cross-sections of commonly used non-resonant processes. The rate that can be achieved at a small distance between the source and two targets of 10{sup 3} kg is up to one interaction per 8.3.10{sup 18} decaying atoms. For a source-target distance corresponding to the first atmospheric neutrino oscillation maximum, the largest rate is one interaction per 3.2.10{sup 21} decaying atoms, provided that extremely stringent monochromaticity conditions (10{sup -7} or better) are achieved in future ion beams. (orig.)

  4. S-Matrix theory of laser-induced nonsequential double ionization: from electron-electron dynamics to absolute-phase diagnosis

    International Nuclear Information System (INIS)

    Figueira de Morisson Faria, C.; Sanpera, A.; Lewenstein, M.; Schomerus, H.; Liu, X.; Becker, W.

    2005-01-01

    Full text: We provide a summarizing account of a series of investigations, in which laser-induced nonsequential double ionization (NSDI) is described as the inelastic collision of an electron with its parent ion, and treated quantummechanically, within the strong-field approximation. In particular, we employ a specific uniform saddle-point approximation whose only validity requirement is that the saddles occur in pairs. As a first step, we address the question of how the type of the interaction by which the second electron is dislodged, as well as final-state electron-electron repulsion, influences the NDSI differential electron momentum distributions. We found that a contact-type interaction and uncorrelated final electron states yields the best agreement with the experimental results, namely circular-shaped distributions peaked at p 1II = p 2II = ±2 √U p , where p nII (n = 1,2) denotes the electron momentum components parallel to the laser-field polarization and U p the ponderomotive energy. Final-state repulsion leads to a broadening in such distributions, with respect to p 1II = p 2II , whereas a Coulomb-type interaction favors unequal momenta. The influence of the interaction and of final-state electron-electron repulsion is most extreme if at least one of the transverse momentum components is kept small, while, for large transverse momenta, different types of interaction or two-electron final states lead to minor discrepancies. In all cases, we obtain very similar results as compared to a classical ensemble computation, in which electrons are released with a quasi-static tunneling rate, apart from minor differences near the boundary of the momentum region for which the collision process in question is classically allowed. Such results suggest that the residual ion has a strong influence on the dynamics of both electrons in NSDI, screening the long-range interaction and the final-state Coulomb repulsion. This interpretation is strengthened by more recent

  5. Nanobiotechnology in energy, environment and electronics methods and applications

    CERN Document Server

    Nicolini, Claudio

    2015-01-01

    Introduction: Present Challenges and Future Solutions via Nanotechnology for Electronics, Environment and Energy; Claudio NicoliniPart A: MethodsInfluence of Chromosome Translocation on Yeast Life Span: Implications for Long-Term Industrial Biofermentation; Jason Sims, Dmitri Nikitin, and Carlo V. BruschiPulsed Power Nanotechnologies for Disintegration and Breaking Up of Refractory Precious Metals Ores; Valentin A. Chanturiya and Igor Zh. BuninModeling of Software Sensors in Bioprocess; Luca Belmonte and Claudio NicoliniN

  6. Generation and characterization of warm dense matter isochorically heated by laser-induced relativistic electrons in a wire target

    Science.gov (United States)

    Schönlein, A.; Boutoux, G.; Pikuz, S.; Antonelli, L.; Batani, D.; Debayle, A.; Franz, A.; Giuffrida, L.; Honrubia, J. J.; Jacoby, J.; Khaghani, D.; Neumayer, P.; Rosmej, O. N.; Sakaki, T.; Santos, J. J.; Sauteray, A.

    2016-05-01

    We studied the interaction of a high-intensity laser with mass-limited Ti-wires. The laser was focused up to 7× 1020 \\text{W/cm}2 , with contrast of 10-10 to produce relativistic electrons. High-spatial-resolution X-ray spectroscopy was used to measure isochoric heating induced by hot electrons propagating along the wire up to 1 mm depth. For the first time it was possible to distinguish surface target regions heated by mixed plasma mechanisms from those heated only by the hot electrons that generate warm dense matter with temperatures up to 50 eV. Our results are compared to simulations that highlight both the role of electron confinement inside the wire and the importance of resistive stopping powers in warm dense matter.

  7. The electronic origin of shear-induced direct to indirect gap transition and anisotropy diminution in phosphorene.

    Science.gov (United States)

    Sa, Baisheng; Li, Yan-Ling; Sun, Zhimei; Qi, Jingshan; Wen, Cuilian; Wu, Bo

    2015-05-29

    Artificial monolayer black phosphorus, so-called phosphorene, has attracted global interest with its distinguished anisotropic, optoelectronic, and electronic properties. Here, we unraveled the shear-induced direct-to-indirect gap transition and anisotropy diminution in phosphorene based on first-principles calculations. Lattice dynamic analysis demonstrates that phosphorene can sustain up to 10% applied shear strain. The bandgap of phosphorene experiences a direct-to- indirect transition when 5% shear strain is applied. The electronic origin of the direct-to-indirect gap transition from 1.54 eV at ambient conditions to 1.22 eV at 10% shear strain for phosphorene is explored. In addition, the anisotropy diminution in phosphorene is discussed by calculating the maximum sound velocities, effective mass, and decomposed charge density, which signals the undesired shear-induced direct-to-indirect gap transition in applications of phosphorene for electronics and optoelectronics. On the other hand, the shear-induced electronic anisotropy properties suggest that phosphorene can be applied as the switcher in nanoelectronic applications.

  8. THE EFFECTS OF ELECTRON-BEAM-INDUCED ELECTRIC FIELD ON THE GENERATION OF LANGMUIR TURBULENCE IN FLARING ATMOSPHERES

    International Nuclear Information System (INIS)

    Zharkova, Valentina V.; Siversky, Taras V.

    2011-01-01

    The precipitation of an electron beam injected into the solar atmosphere is studied for the generation of Langmuir wave turbulence in the presence of collisional and Ohmic losses. The system of quasi-linear time-dependent kinetic equations describing the evolution of beams and Langmuir waves is solved by using the summary approximation method. It is found that at upper atmospheric levels the self-induced electric field suppresses the generation of Langmuir turbulence to very small regions below injection. With further precipitation into deeper atmosphere the initial single power-law distributions of beam electrons are transformed into energy distributions with maxima at lower energies formed by collisional and Ohmic energy depletion. The electrons with lower energies (<20 keV) generate on large spatial scales intense low-hybrid and high-hybrid Langmuir waves with well-defined patterns in the corona while higher energy electrons generate moderate low-hybrid waves in the chromosphere. The maximum wave density appears at the maximum of the ambient density. The self-induced electric field reduces the level and makes the regions with low-hybrid Langmuir turbulence narrower in the corona and upper chromosphere. The higher the beam energy flux or its self-induced electric field, the narrower the regions with Langmuir turbulence. High-hybrid Langmuir waves in the form of multiple patterns in space (in the corona) and energy (below 20 keV) are found to be generated only by a very intense electron beam. The number of patterns in both dimensions is also shown to be significantly reduced by the self-induced electric field.

  9. Neutron yield and induced radioactivity: a study of 235-MeV proton and 3-GeV electron accelerators

    International Nuclear Information System (INIS)

    Hsu, Yung-Cheng; Lai, Bo-Lun; Sheu, Rong-Jiun

    2016-01-01

    This study evaluated the magnitude of potential neutron yield and induced radioactivity of two new accelerators in Taiwan: a 235-MeV proton cyclotron for radiation therapy and a 3-GeV electron synchrotron serving as the injector for the Taiwan Photon Source. From a nuclear interaction point of view, neutron production from targets bombarded with high-energy particles is intrinsically related to the resulting target activation. Two multi-particle interaction and transport codes, FLUKA and MCNPX, were used in this study. To ensure prediction quality, much effort was devoted to the associated benchmark calculations. Comparisons of the accelerators' results for three target materials (copper, stainless steel and tissue) are presented. Although the proton-induced neutron yields were higher than those induced by electrons, the maximal neutron production rates of both accelerators were comparable according to their respective beam outputs during typical operation. Activation products in the targets of the two accelerators were unexpectedly similar because the primary reaction channels for proton- and electron-induced activation are (p,pn) and (γ,n), respectively. The resulting residual activities and remnant dose rates as a function of time were examined and discussed. (authors)

  10. Neutron yield and induced radioactivity: a study of 235-MeV proton and 3-GeV electron accelerators.

    Science.gov (United States)

    Hsu, Yung-Cheng; Lai, Bo-Lun; Sheu, Rong-Jiun

    2016-01-01

    This study evaluated the magnitude of potential neutron yield and induced radioactivity of two new accelerators in Taiwan: a 235-MeV proton cyclotron for radiation therapy and a 3-GeV electron synchrotron serving as the injector for the Taiwan Photon Source. From a nuclear interaction point of view, neutron production from targets bombarded with high-energy particles is intrinsically related to the resulting target activation. Two multi-particle interaction and transport codes, FLUKA and MCNPX, were used in this study. To ensure prediction quality, much effort was devoted to the associated benchmark calculations. Comparisons of the accelerators' results for three target materials (copper, stainless steel and tissue) are presented. Although the proton-induced neutron yields were higher than those induced by electrons, the maximal neutron production rates of both accelerators were comparable according to their respective beam outputs during typical operation. Activation products in the targets of the two accelerators were unexpectedly similar because the primary reaction channels for proton- and electron-induced activation are (p,pn) and (γ,n), respectively. The resulting residual activities and remnant dose rates as a function of time were examined and discussed. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Exploring ultrashort high-energy electron-induced damage in human carcinoma cells

    International Nuclear Information System (INIS)

    Rigaud, O.; Fortunel, N.O.; Vaigot, P.; Cadio, E.; Martin, M.T.; Lundh, O.; Faure, J.; Rechatin, C.; Malka, V.; Gauduel, Y.A.

    2010-01-01

    In conventional cancer therapy or fundamental radiobiology research, the accumulated knowledge on the complex responses of healthy or diseased cells to ionizing radiation is generally obtained with low-dose rates. Under these radiation conditions, the time spent for energy deposition is very long compared with the dynamics of early molecular and cellular responses. The use of ultrashort pulsed radiation would offer new perspectives for exploring the 'black box' aspects of long irradiation profiles and favouring the selective control of early damage in living targets. Several attempts were previously performed using nanosecond or picosecond pulsed irradiations on various mammalian cells and radiosensitive mutants at high dose rate. The effects of single or multi-pulsed radiations on cell populations were generally analyzed in the framework of dose survival curves or characterized by 2D imaging of γ-H2AX foci and no increase in cytotoxicity was shown compared with a delivery at a conventional dose rate. Moreover, when multi-shot irradiations were performed, the overall time needed to obtain an integrated dose of several Grays again overlapped with the multi-scale dynamics of bio-molecular damage-repair sequences and cell signalling steps. Ideally, a single-shot irradiation delivering a well-defined energy profile, via a very short temporal window, would permit the approach of a real-time investigation of early radiation induced molecular damage within the confined spaces of cell compartments. Owing to the potential applications of intense ultrashort laser for radiation therapy, the model of the A431 carcinoma cell line was chosen. An ultrafast single-shot irradiation strategy was carried out with these radio-resistant human skin carcinoma cells, using the capacity of an innovating laser-plasma accelerator to generate quasi mono-energetic femtosecond electron bunches in the MeV domain and to deliver a very high dose rate of 10 13 Gy s -1 per pulse. The alkaline comet

  12. Dynamical coupling of electrons and ions in Xray-induced dynamics

    International Nuclear Information System (INIS)

    Saalmann, Ulf; Camacho, Abraham; Rost, Jan-Michael

    2015-01-01

    Photo-absorption from short and intense Xray pulses by a molecule or a cluster triggers a complicated electron and ion dynamics. Whereas the excitation process concerns largely core-shell electrons, there are various subsequent relaxation channels like electronic decays and ionic Coulomb explosion. We will discuss the interplay of those processes for molecular clusters and fullerenes. (paper)

  13. Production and stability of radiation-induced defects in MgAl2O4 under electronic excitation

    International Nuclear Information System (INIS)

    Yasuda, K.; Yamamoto, T.; Seki, S.; Shiiyama, K.; Matsumura, S.

    2008-01-01

    This paper investigates the formation process of radiation-induced defects in magnesium aluminate spinel and their stability using transmission electron microscopy, with emphasis on the effects of electronic excitation. Small interstitial-type dislocation loops disappeared under electron-induced electronic excitation. The elimination rate of the loops was found to be one order higher than for α-alumina. The disappearance of dislocation loops by a dissociation mechanism into isolated interstitials is discussed through analysis of the growth-and-shrink process of the loops. HARECXS analysis on cross section specimens irradiated with 350 MeV Au ions has shown the progress of cation disordering along ion tracks to be a function of electronic stopping power, (dE/dx) e . Cations were found to exchange their sites toward a random configuration. Such disordering appears from (dE/dx) e = 10 keV/nm, and increases in size with increasing (dE/dx) e to reach nearly 10 nm in diameter at 30 keV/nm, under an assumption of a fully disordered configuration

  14. Radiation-Induced α' Phase Formation on Dislocation Loops in Fe-Cr Alloys During Electron Irradiation

    OpenAIRE

    Wakai, E.; Hishinuma, A.; Kato, Y.; Yano, H.; Takaki, S.; Abiko, K.

    1995-01-01

    Radiation-induced precipitates on dislocation loops in low and high purity Fe-9, -18 and -50 % Cr alloys were examined under electron irradiation in a high voltage electron microscope operated at 1 MV. Two types of dislocation loops on {100} planes with a Burgers vectors and on {111} planes with a /2 are formed in high purity Fe-Cr alloys. However, only a type loops are formed in low purity alloys, i.e. where carbon concentration is greater than about 60 wt.ppm. The growth rate of the loops...

  15. Development of phosphonic acid chelating fibers by means of electron beam irradiation induced graft polymerization technique

    International Nuclear Information System (INIS)

    Jyo, Akinori; Aoki, Shoji; Yamabe, Kazunori; Shuto, Taketomi

    2001-01-01

    Chloromethylstyrene was graft-polymerized onto polyethylene coated polypropylene fibers (0.9 denier) and its nonwoven cloth (1.5 denier) by means of electron beam irradiation induced graft polymerization technique. The grafted fiber and cloth were reacted with phosphorus trichloride in the presence of anhydrous aluminum trichloride under reflux of phosphorus trichloride, and the followed hydrolysis gave the objective phosphonic acid fibrous chelating exchangers FCSP-c (cloth type) and FCSP-f (fiber type) with phosphorus contents of 3.3 ± 0.2 mmol/g and acid capacities of 5.5 ± 0.2 meq/g. Adsorption rates of Pb(II), Cu(II) and Cd(II) by FCSP-c and FCSP-f were evaluated by batchwise and columnar methods, and compared with those by a chelating resin RCSP having the same functional groups. In batchwise and columnar adsorption of these metal ions, both FCSP-c and FCSP-f exhibited extremely higher adsorption rates than did the resin RCSP. For instance, FCSP-f packed columns exhibited flow rate independent breakthrough capacities of ca. 0.7-0.8 mmol/g for Cu(II) and Cd(II) within the tested range of flow rates from 50 to 1000 h -1 in space velocity, whereas breakthrough capacities of a RCSP resin packed one for Cu(II) decreased markedly with an increase in flow rate. For example, the breakthrough capacity of RCSP column at the flow rate of 500 h -1 was only ca. 0.2 mmol/g. (author)

  16. Electron Transfer Dissociation and Collision-Induced Dissociation of Underivatized Metallated Oligosaccharides

    Science.gov (United States)

    Schaller-Duke, Ranelle M.; Bogala, Mallikharjuna R.; Cassady, Carolyn J.

    2018-02-01

    Electron transfer dissociation (ETD) and collision-induced dissociation (CID) were used to investigate underivatized, metal-cationized oligosaccharides formed via electrospray ionization (ESI). Reducing and non-reducing sugars were studied including the tetrasaccharides maltotetraose, 3α,4β,3α-galactotetraose, stachyose, nystose, and a heptasaccharide, maltoheptaose. Univalent alkali, divalent alkaline earth, divalent and trivalent transition metal ions, and a boron group trivalent metal ion were adducted to the non-permethylated oligosaccharides. ESI generated [M + Met]+, [M + 2Met]2+, [M + Met]2+, [M + Met - H]+, and [M + Met - 2H]+ most intensely along with low intensity nitrate adducts, depending on the metal and sugar ionized. The ability of these metal ions to produce oligosaccharide adduct ions by ESI had the general trend: Ca(II) > Mg(II) > Ni(II) > Co(II) > Zn(II) > Cu(II) > Na(I) > K(I) > Al(III) ≈ Fe(III) ≈ Cr(III). Although trivalent metals were utilized, no triply charged ions were formed. Metal cations allowed for high ESI signal intensity without permethylation. ETD and CID on [M + Met]2+ produced various glycosidic and cross-ring cleavages, with ETD producing more cross-ring and internal ions, which are useful for structural analysis. Product ion intensities varied based on glycosidic-bond linkage and identity of monosaccharide sub-unit, and metal adducts. ETD and CID showed high fragmentation efficiency, often with complete precursor dissociation, depending on the identity of the adducted metal ion. Loss of water was occasionally observed, but elimination of small neutral molecules was not prevalent. For both ETD and CID, [M + Co]2+ produced the most uniform structurally informative dissociation with all oligosaccharides studied. The ETD and CID spectra were complementary. [Figure not available: see fulltext.

  17. Electron microscopic observations and DNA chain fragmentation studies on apoptosis in bone tumor cells induced by 153Sm-EDTMP

    International Nuclear Information System (INIS)

    Zhu Shoupeng; Xiao Dong; Han Xiaofeng

    1997-01-01

    The morphological changes observed by electron microscopy indicate that after internal irradiation with 153 Sm-EDTMP bone tumor cells displayed feature of apoptosis, such as margination of condensed chromatin, chromatin fragmentation, as well as the membrane bounded apoptotic bodies formation. The quantification analysis of fragmentation DNA for bone tumor cells induced by 153 Sm-EDTMP shows that the DNA fragmentation is enhanced with the prolongation of internally irradiated time. These characteristics suggest that 153 Sm-EDTMP internal irradiation could induce bone tumor cells to go to apoptosis

  18. Role of Mitochondrial Electron Transport Chain Dysfunction in Cr(VI-Induced Cytotoxicity in L-02 Hepatocytes

    Directory of Open Access Journals (Sweden)

    Fang Xiao

    2014-04-01

    Full Text Available Background: Hexavalent chromium [Cr(VI] and its compounds (e.g. chromates, which are extensively used in numerous industrial processes including leather tanning and steel manufacturing, are considered as priority pollutants. There is growing evidence supporting that Cr(VI could be a human carcinogen that induces primary liver cancer after oral exposure, and this sheds light on the importance of the investigation of Cr(VI-induced hepatotoxicity. Although it is known that mitochondria are major targets for heavy metals, the mechanisms of electron transfer chain (ETC dysfunction involved in Cr(VI-induced cytotoxicity are unclear. Methods: In the present study, by using mitochondrial respiratory chain complex (MRCC I inhibitor rotenone (ROT and its substrates glutamate/malate (Glu/Mal, MRCC III inhibitor antimycin A (AA and its substrate coenzyme Q (CoQ, and the antioxidant Vitamin C (Vit C, we aimed to elucidate the role of mitochondrial ETC dysfunction in Cr(VI-induced cytotoxicity. Results: We found that Cr(VI targeted and inhibited MRCC I and III to induce ETC dysfunction, which played an important role in Cr(VI-induced cytotoxicity. Conclusion: Our current data provides novel important insight into the mechanisms of mitochondrial ETC dysfunction in Cr(VI-induced cytotoxicity in the hepatocytes, and we will be poised to develop new methods in the prevention and treatment of liver diseases involving mitochondrial ETC dysfunction for the occupational exposure population.

  19. Tensile strain-induced magnetism transition in multilayer graphene with excess electrons: Stability of the edge-quantum well

    Directory of Open Access Journals (Sweden)

    Lei Yang

    2015-12-01

    Full Text Available The stability of edge-quantum well-induced strong magnetism of multilayer armchair graphene nanoribbon (AGNR with excess electrons was investigated under applied tensile strain by density functional theory (DFT calculations. The results indicated that: (1 The strain along the armchair edge direction led to a transition of the multilayer AGNRs from ferromagnetic state to nonmagnetic state when the strain increased to a critical value; (2 The strain induced bond length changes reduced the stability of the edge-quantum well in terms of the reduction of the electrons capturing capacity; and (3 The spin splitting of the energy bands near the Fermi level reduced with the increase of the strain, resulting in the decrease of the spin moment. This finding suggests that the magnetic properties of graphene have strong dependence on its strain states, which is crucial to the design of graphene-based magnetic devices.

  20. Evaluation of induced radioactivity in 10 MeV-Electron irradiated spices, (2); [beta]-ray counting

    Energy Technology Data Exchange (ETDEWEB)

    Katayama, Tadashi; Furuta, Masakazu; Shibata, Setsuko; Matsunami, Tadao; Ito, Norio; Mizohata, Akira; Toratani, Hirokazu (Osaka Prefectural Univ., Sakai (Japan). Research Inst. for Advanced Science and Technology); Takeda, Atsuhiko

    1994-02-01

    In order to check radioactivity of beta-emmitters produced by ([gamma], n) reactions which could occur at energies up to 10 MeV, black pepper, white pepper, red pepper, ginger and turmeric were irradiated with 10 MeV electron from a linear accelerator to a dose of 100 kGy. Beta-rays were counted using a 2[pi] gas flow counter and a liquid scintillation counter. Any induced radioactivity could not be detected in irradiated samples. When inorganic compounds containing the nuclides in the list were artificially added in the samples and were irradiated, the [beta]-activities were detected. From the amount of observed radioactivities of [beta]-emmitters produced in the compounds as photonuclear products, it is concluded that the induced radioactivity in natural samples by 10 MeV-electron irradiation were far smaller than natural radioactivity from [sup 40]K contained in the samples and, hence, its biological effects should be negligible. (author).

  1. Thon rings from amorphous ice and implications of beam-induced Brownian motion in single particle electron cryo-microscopy.

    Science.gov (United States)

    McMullan, G; Vinothkumar, K R; Henderson, R

    2015-11-01

    We have recorded dose-fractionated electron cryo-microscope images of thin films of pure flash-frozen amorphous ice and pre-irradiated amorphous carbon on a Falcon II direct electron detector using 300 keV electrons. We observe Thon rings [1] in both the power spectrum of the summed frames and the sum of power spectra from the individual frames. The Thon rings from amorphous carbon images are always more visible in the power spectrum of the summed frames whereas those of amorphous ice are more visible in the sum of power spectra from the individual frames. This difference indicates that while pre-irradiated carbon behaves like a solid during the exposure, amorphous ice behaves like a fluid with the individual water molecules undergoing beam-induced motion. Using the measured variation in the power spectra amplitude with number of electrons per image we deduce that water molecules are randomly displaced by a mean squared distance of ∼1.1 Å(2) for every incident 300 keV e(-)/Å(2). The induced motion leads to an optimal exposure with 300 keV electrons of 4.0 e(-)/Å(2) per image with which to observe Thon rings centred around the strong 3.7 Å scattering peak from amorphous ice. The beam-induced movement of the water molecules generates pseudo-Brownian motion of embedded macromolecules. The resulting blurring of single particle images contributes an additional term, on top of that from radiation damage, to the minimum achievable B-factor for macromolecular structure determination. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  2. Proton Irradiation-Induced Metal Voids in Gallium Nitride High Electron Mobility Transistors

    Science.gov (United States)

    2015-09-01

    13. ABSTRACT (maximum 200 words) Gallium nitride / aluminum gallium nitride high electron mobility transistors with nickel/gold (Ni/Au) and...Engineering iv THIS PAGE INTENTIONALLY LEFT BLANK v ABSTRACT Gallium nitride / aluminum gallium nitride high electron mobility transistors with...ABBREVIATIONS 2DEG two-dimensional electron gas AlGaN aluminum gallium nitride AlOx aluminum oxide CCD charged coupled device CTE coefficient of

  3. Photoelectric charging of dust particles: Effect of spontaneous and light induced field emission of electrons

    International Nuclear Information System (INIS)

    Sodha, M. S.; Dixit, A.

    2009-01-01

    The authors have analyzed the charging of dust particles in a plasma, taking into account the electron/ion currents to the particles, electron/ion generation and recombination, electric field emission, photoelectric emission and photoelectric field emission of electrons under the influence of light irradiation; the irradiance has been assumed to be at a level, which lets the particles retain the negative sign of the charge. Numerical results and discussion conclude the papers.

  4. Phonon-induced renormalization of the electron spectrum of biased bilayer graphene

    Science.gov (United States)

    Kryuchkov, S. V.; Kukhar, E. I.

    2018-05-01

    The effect of the electron-phonon interaction on the electron subsystem of the bilayer graphene has been investigated in the case when there is a potential bias between the graphene layers. The electron-phonon interaction has been shown to lead to increasing of the curvature of the lower dispersion branch of the conduction band of the bigraphene in the vicinity of the Dirac point. The latter corresponds to the decreasing of the absolute value of the electron effective mass. The corresponding correction to the effective mass has been calculated. Dependence of this correction on the bias has been investigated. Influence of such effect on the bigraphene conductivity is discussed.

  5. Contribution of charge-transfer processes to ion-induced electron emission

    International Nuclear Information System (INIS)

    Roesler, M.; Garcia de Abajo, F.J.

    1996-01-01

    Charge changing events of ions moving inside metals are shown to contribute significantly to electron emission in the intermediate velocity regime via electrons coming from projectile ionization. Inclusion of equilibrium charge state fractions, together with two-electron Auger processes and resonant-coherent electron loss from the projectile, results in reasonable agreement with previous calculations for frozen protons, though a significant part of the emission is now interpreted in terms of charge exchange. The quantal character of the surface barrier transmission is shown to play an important role. The theory compares well with experimental observations for H projectiles. copyright 1996 The American Physical Society

  6. Unified first principles description from warm dense matter to ideal ionized gas plasma: electron-ion collisions induced friction.

    Science.gov (United States)

    Dai, Jiayu; Hou, Yong; Yuan, Jianmin

    2010-06-18

    Electron-ion interactions are central to numerous phenomena in the warm dense matter (WDM) regime and at higher temperature. The electron-ion collisions induced friction at high temperature is introduced in the procedure of ab initio molecular dynamics using the Langevin equation based on density functional theory. In this framework, as a test for Fe and H up to 1000 eV, the equation of state and the transition of electronic structures of the materials with very wide density and temperature can be described, which covers a full range of WDM up to high energy density physics. A unified first principles description from condensed matter to ideal ionized gas plasma is constructed.

  7. Laser Induced Forward Transfer of High Viscosity Silver Paste for New Metallization Methods in Photovoltaic and Flexible Electronics Industry

    Science.gov (United States)

    Chen, Y.; Munoz-Martin, D.; Morales, M.; Molpeceres, C.; Sánchez-Cortezon, E.; Murillo-Gutierrez, J.

    Laser Induced Forward Transfer (LIFT) has been studied in the past as a promising approach for precise metallization in electronics using metallic inks and pastes. In this work we present large area metallization using LIFT of fully commercial silver-based pastes initially designed for solar cell screen-printing. We discuss the mechanisms for the material transfer both in ns and ps regimes of irradiation of these high viscosity materials, and the potential use of this technique in the photovoltaic industry (both in standard c-Si solar cells and thin film technologies) and flexible electronics devices. In particular we summarize the results of our group in this field, demonstrating that our approach is capable of improving the aspect ratio of the standard metallization patterns achieved with screen-printing technologies in those technological fields and, in addition, of fulfilling the requirements imposed by the mechanical properties of the substrates in flexible electronic applications.

  8. Dynamics of surface-migration: Electron-induced reaction of 1,2-dihaloethanes on Si(100)

    Science.gov (United States)

    Huang, Kai; MacLean, Oliver; Guo, Si Yue; McNab, Iain R.; Ning, Zhanyu; Wang, Chen-Guang; Ji, Wei; Polanyi, John C.

    2016-10-01

    Scanning Tunneling Microscopy was used to investigate the electron-induced reaction of 1,2-dibromoethane (DBE) and 1,2-dichloroethane (DCE) on Si(100).We observed a long-lived physisorbed molecular state of DBE at 75 K and of DCE at 110 K. As a result we were able to characterize by experiment and also by ab initio theory the dynamics of ethylene production in the electron-induced surface-reaction of these physisorbed species. For both DBE and DCE the ethylene product was observed to migrate across the surface. In the case of DBE the recoil of the ethylene favored the silicon rows, migrating by an average distance of 22 Å, and up to 100 Å. Trajectory calculations were performed for this electron-induced reaction, using an 'Impulsive Two-State' model involving an anionic excited state and a neutral ground-potential. The model agreed with experiment in reproducing both migration and desorption of the ethylene product. The computed migration exhibited a 'ballistic' launch and subsequent 'bounces', thereby accounting for the observed long-range migratory dynamics.

  9. The effects of various gate oxidation conditions on intrinsic and radiation-induced extrinsic charged defects and neutral electron traps

    International Nuclear Information System (INIS)

    Walters, M.; Reisman, A.

    1990-01-01

    In this paper the influence of the oxidation temperature, ambient atmosphere, and oxidation rate on intrinsic and Al Kα x-ray radiation-induced extrinsic gate oxide defect levels in insulated-gate field effect transistors (IGFETs) is studied. Using optically assisted electron injection into n-channel polysilicon-gated IGFETs, neutral electron trap and fixed negative charge defect densities were measured, in addition to the fixed positive charge density. The results indicate that radiation-induced defect densities in the gate oxide decrease with increasing oxidation temperature in the 800 degrees C to 1000 degrees C range, and are lower for dry/wet/dry oxides than for dry oxides when the oxidation temperature is below 950 degrees C, but higher when the oxidation temperature is above 950 degrees C. The oxidation rate had no effect on defect levels in dry oxides grown at 1000 degrees CX, while at an oxidation temperature of 800 degrees C, the extrinsic defect densities were observed to increase when the oxidation rate was decreased. In all cases, the radiation-induced fixed positive charge and neutral electron trap defect densities were observed to be dependent upon the gate oxidation conditions in the same fashion

  10. Electronic excitation-induced structural, optical, and magnetic properties of Ni-doped HoFeO3 thin films

    International Nuclear Information System (INIS)

    Habib, Zubida; Ikram, Mohd; Mir, Sajad A.; Sultan, Khalid; Abida; Majid, Kowsar; Asokan, K.

    2017-01-01

    Present study investigates the electronic excitation-induced modifications in the structural, optical, and magnetic properties of Ni-doped HoFeO 3 thin films grown by pulsed laser deposition on LaAlO 3 substrates. Electronic excitations were induced by 200 MeV Ag 12+ ion beam. These thin films were then characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), UV-Vis spectroscopy, and magnetic measurements. X-ray diffraction analysis confirms that the crystallite growth occurs in the preferred (111) orientation with orthorhombic structure. The XRD results also show that the crystallite size decreases with ion irradiation. AFM results after irradiation show significant changes in the surface roughness and morphology of these films. The optical parameters measured from absorption measurements reveal reduction in the band gap with Ni doping and enhancement of band gap after irradiation. The magnetization vs field measurement at 75 K shows enhancement in saturation magnetization after irradiation for HoFe 1-x Ni x O 3 (x = 0.1 and 0.3) films compared to HoFeO 3 film. Present study shows electronic excitation induces significant changes in the physical properties of these films. (orig.)

  11. Synthesis of ZnO nanocoatings by decomposition of zinc acetate induced by electrons emitted by indium

    Energy Technology Data Exchange (ETDEWEB)

    Svoboda, Ladislav [Department of Chemistry, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, Ostrava 708 33 (Czech Republic); Institute of Environmental Technologies, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, Ostrava 708 33 (Czech Republic); Dvorský, Richard [Department of Physics, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, Ostrava 708 33 (Czech Republic); Regional Materials Science and Technology Centre, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, Ostrava 708 33 (Czech Republic); Nanotechnology Centre, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, Ostrava 708 33 (Czech Republic); Praus, Petr, E-mail: petr.praus@vsb.cz [Department of Chemistry, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, Ostrava 708 33 (Czech Republic); Institute of Environmental Technologies, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, Ostrava 708 33 (Czech Republic); Matýsek, Dalibor [Institute of Geological Engineering, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, Ostrava 708 33 (Czech Republic); Bednář, Jiří [Nanotechnology Centre, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, Ostrava 708 33 (Czech Republic)

    2016-12-01

    Graphical abstract: - Highlights: • Hexagonal ZnO was synthetized by the decomposition of zinc acetate under UV light. • Source of photogenerated electron was an indium plate. • ZnO nanocoatings were deposited on surface of silica nanoparticles. • Mean thickness of the ZnO nanocoatings was estimated by DLS at 13 nm. - Abstract: In this work, a new method for the synthesis of ZnO nanocoatings is presented. It was tested for the nanocoating of silica nanoparticles forming core/shell SiO{sub 2}/ZnO nanoparticles by the decomposition of zinc acetate in silica aqueous nanodispersions induced by electrons generated by a plate indium photocathode, which was irradiated with a UV Hg lamp with maximum intensity at the wavelength of 245 nm. The ZnO nanocoatings were examined by X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PLS), dynamic light scattering (DLS) and transmission electron microscopy (TEM). It was found that ZnO of hexagonal structure formed nanocoatings with the mean thickness of 13 nm. The photocatalytic activity of ZnO nanocoatings was verified by the photocatalytic decomposition of methylene blue (MB). Such nanocoating procedure based on the electron-induced decomposition of suitable metal salts could be a promising method for various applications in nanotechnology.h.

  12. In situ transmission electron microscope studies of ion irradiation-induced and irradiation-enhanced phase changes

    International Nuclear Information System (INIS)

    Allen, C.W.

    1992-01-01

    Motivated at least initially by materials needs for nuclear reactor development, extensive irradiation effects studies employing transmission electron microscopes (TEM) have been performed for several decades, involving irradiation-induced and irradiation-enhanced microstructural changes, including phase transformations such as precipitation, dissolution, crystallization, amorphization, and order-disorder phenomena. From the introduction of commercial high voltage electron microscopes (HVEM) in the mid-1960s, studies of electron irradiation effects have constituted a major aspect of HVEM application in materials science. For irradiation effects studies two additional developments have had particularly significant impact; the development of TEM specimen holder sin which specimen temperature can be controlled in the range 10-2200 K and the interfacing of ion accelerators which allows in situ TEM studies of irradiation effects and the ion beam modification of materials within this broad temperature range. This paper treats several aspects of in situ studies of electron and ion beam-induced and enhanced phase changes and presents two case studies involving in situ experiments performed in an HVEM to illustrate the strategies of such an approach of the materials research of irradiation effects

  13. Low-energy electron-induced chemistry of condensed methanol: implications for the interstellar synthesis of prebiotic molecules.

    Science.gov (United States)

    Boamah, Mavis D; Sullivan, Kristal K; Shulenberger, Katie E; Soe, ChanMyae M; Jacob, Lisa M; Yhee, Farrah C; Atkinson, Karen E; Boyer, Michael C; Haines, David R; Arumainayagam, Christopher R

    2014-01-01

    In the interstellar medium, UV photolysis of condensed methanol (CH3OH), contained in ice mantles surrounding dust grains, is thought to be the mechanism that drives the formation of "complex" molecules, such as methyl formate (HCOOCH3), dimethyl ether (CH3OCH3), acetic acid (CH3COOH), and glycolaldehyde (HOCH2CHO). The source of this reaction-initiating UV light is assumed to be local because externally sourced UV radiation cannot penetrate the ice-containing dark, dense molecular clouds. Specifically, exceedingly penetrative high-energy cosmic rays generate secondary electrons within the clouds through molecular ionizations. Hydrogen molecules, present within these dense molecular clouds, are excited in collisions with these secondary electrons. It is the UV light, emitted by these electronically excited hydrogen molecules, that is generally thought to photoprocess interstellar icy grain mantles to generate "complex" molecules. In addition to producing UV light, the large numbers of low-energy (methanol, a precursor of several prebiotic species, is the most abundant organic species. Using post-irradiation temperature-programmed desorption, we have investigated the radiolysis initiated by low-energy (7 eV and 20 eV) electrons in condensed methanol at - 85 K under ultrahigh vacuum (5 x 10(-10) Torr) conditions. We have identified eleven electron-induced methanol radiolysis products, which include many that have been previously identified as being formed by methanol UV photolysis in the interstellar medium. These experimental results suggest that low-energy, electron-induced condensed phase reactions may contribute to the interstellar synthesis of "complex" molecules previously thought to form exclusively via UV photons.

  14. Investigations of a Cretaceous limestone with spectral induced polarization and scanning electron microscopy

    Science.gov (United States)

    Johansson, Sara; Sparrenbom, Charlotte; Fiandaca, Gianluca; Lindskog, Anders; Olsson, Per-Ivar; Dahlin, Torleif; Rosqvist, Håkan

    2017-02-01

    Characterization of varying bedrock properties is a common need in various contexts, ranging from large infrastructure pre-investigations to environmental protection. A direct current resistivity and time domain induced polarization (IP) survey aiming to characterize properties of a Cretaceous limestone was carried out in the Kristianstad basin, Sweden. The time domain IP data was processed with a recently developed method in order to suppress noise from the challenging urban setting in the survey area. The processing also enabled extraction of early decay times resulting in broader spectra of the time decays and inversion for Cole-Cole parameters. The aims of this study is to investigate if large-scale geoelectrical variations as well as small-scale structural and compositional variations exist within the Kristianstad limestone, and to evaluate the usefulness of Cole-Cole inverted IP data in early time ranges for bedrock characterization. The inverted sections showed variations within the limestone that could be caused by variations in texture and composition. Samples from a deep drilling in the Kristianstad basin were investigated with scanning electron microscopy and energy dispersive X-ray spectroscopy, and the results showed that varying amounts of pyrite, glauconite and clay matrix were present at different levels in the limestone. The local high IP anomalies in the limestone could be caused by these minerals otherwise the IP responses were generally weak. There were also differences in the texture of the limestone at different levels, governed by fossil shapes and composition, proportions of calcareous cement and matrix as well as amount of silicate grains. Textural variations may have implications on the variation in Cole-Cole relaxation time and frequency factor. However, more research is needed in order to directly connect microgeometrical properties in limestone to spectral IP responses. The results from this study show that it is possible to recover

  15. A single-electron reducing quinone oxidoreductase is necessary to induce haustorium development in the root parasitic plant Triphysaria.

    Science.gov (United States)

    Bandaranayake, Pradeepa C G; Filappova, Tatiana; Tomilov, Alexey; Tomilova, Natalya B; Jamison-McClung, Denneal; Ngo, Quy; Inoue, Kentaro; Yoder, John I

    2010-04-01

    Parasitic plants in the Orobanchaceae develop haustoria in response to contact with host roots or chemical haustoria-inducing factors. Experiments in this manuscript test the hypothesis that quinolic-inducing factors activate haustorium development via a signal mechanism initiated by redox cycling between quinone and hydroquinone states. Two cDNAs were previously isolated from roots of the parasitic plant Triphysaria versicolor that encode distinct quinone oxidoreductases. QR1 encodes a single-electron reducing NADPH quinone oxidoreductase similar to zeta-crystallin. The QR2 enzyme catalyzes two electron reductions typical of xenobiotic detoxification. QR1 and QR2 transcripts are upregulated in a primary response to chemical-inducing factors, but only QR1 was upregulated in response to host roots. RNA interference technology was used to reduce QR1 and QR2 transcripts in Triphysaria roots that were evaluated for their ability to form haustoria. There was a significant decrease in haustorium development in roots silenced for QR1 but not in roots silenced for QR2. The infrequent QR1 transgenic roots that did develop haustoria had levels of QR1 similar to those of nontransgenic roots. These experiments implicate QR1 as one of the earliest genes on the haustorium signal transduction pathway, encoding a quinone oxidoreductase necessary for the redox bioactivation of haustorial inducing factors.

  16. Nanocrystal ghosting: Extensive radiation damage in MgO induced by low-energy electrons

    Energy Technology Data Exchange (ETDEWEB)

    Frankenfield, Zackery [Department of Physics, West Chester University of PA, West Chester, PA 19382 (United States); Kane, Kenneth [Department of Physics, West Chester University of PA, West Chester, PA 19382 (United States); Current address: Department of Physics, Virginia Commonwealth University, Richmond, VA 23228 (United States); Sawyer, William H., E-mail: wsawyer@wcupa.edu [Department of Physics, West Chester University of PA, West Chester, PA 19382 (United States)

    2017-03-15

    We report direct evidence of extensive radiation damage in MgO nanocrystals due to intense bombardment (2 × 10 electrons/nm sec) by electrons with beam energies between 60 keV and 120 keV. Based upon a minimum intensity necessary to produce the observed damage, we present an explanation based on the Knotek-Feibelman process.

  17. Anisotropic Shape Changes of Silica Nanoparticles Induced in Liquid with Scanning Transmission Electron Microscopy

    NARCIS (Netherlands)

    Zecevic, J.; Hermannsdorfer, Justus; Schuh, Tobias; de Jong, Krijn P.; de Jonge, Niels

    2017-01-01

    Liquid-phase transmission electron microscopy (TEM) is used for in-situ imaging of nanoscale processes taking place in liquid, such as the evolution of nanoparticles during synthesis or structural changes of nanomaterials in liquid environment. Here, it is shown that the focused electron beam of

  18. A novel electron beam-induced reaction of sulfonium salt in the crystalline state

    Energy Technology Data Exchange (ETDEWEB)

    Moon, S.; Maekawa, Yasunari; Yoshida, Masaru [Department of Material Development, Takasaki Radiation Chemistry Research Establishment, Japan Atomic Energy Research Institute, Takasaki, Gunma (Japan)

    2001-05-01

    The electron beam irradiation of triphenylsulfonium methanesulfonate in the crystalline state provides a new benzene-substitute sulfonium salt. This product has not been observed either by photolysis in the crystalline state nor by electron beam irradiation in a solution. The formation of the substitution product was confirmed by GC-MS analysis. (author)

  19. Prompt injections of highly relativistic electrons induced by interplanetary shocks: A statistical study of Van Allen Probes observations

    Science.gov (United States)

    Schiller, Q.; Kanekal, S. G.; Jian, L. K.; Li, X.; Jones, A.; Baker, D. N.; Jaynes, A.; Spence, H. E.

    2016-12-01

    We conduct a statistical study on the sudden response of outer radiation belt electrons due to interplanetary (IP) shocks during the Van Allen Probes era, i.e., 2012 to 2015. Data from the Relativistic Electron-Proton Telescope instrument on board Van Allen Probes are used to investigate the highly relativistic electron response (E > 1.8 MeV) within the first few minutes after shock impact. We investigate the relationship of IP shock parameters, such as Mach number, with the highly relativistic electron response, including spectral properties and radial location of the shock-induced injection. We find that the driving solar wind structure of the shock does not affect occurrence for enhancement events, 25% of IP shocks are associated with prompt energization, and 14% are associated with MeV electron depletion. Parameters that represent IP shock strength are found to correlate best with highest levels of energization, suggesting that shock strength may play a key role in the severity of the enhancements. However, not every shock results in an enhancement, indicating that magnetospheric preconditioning may be required.

  20. Photo-induced regeneration of hormones by electron transfer processes: Potential biological and medical consequences

    Energy Technology Data Exchange (ETDEWEB)

    Getoff, Nikola, E-mail: nikola.getoff@univie.ac.a [Section of Radiation Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna (Austria); Hartmann, Johannes [Department of Gynecologic Endocrinology and Reproduction, Medical University of Vienna, A-1090 Vienna (Austria); Schittl, Heike [Section of Radiation Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna (Austria); Gerschpacher, Marion [Department of Gynecologic Endocrinology and Reproduction, Medical University of Vienna, A-1090 Vienna (Austria); Quint, Ruth Maria [Section of Radiation Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna (Austria)

    2011-08-15

    Based on the previous results concerning electron transfer processes in biological substances, it was of interest to investigate if hormone transients resulting by e.g. electron emission can be regenerated. The presented results prove for the first time that the hormone transients originating by the electron emission process can be successfully regenerated by the transfer of electrons from a potent electron donor, such as vitamin C (VitC). Investigations were performed using progesterone (PRG), testosterone (TES) and estrone (E1) as representatives of hormones. By irradiation with monochromatic UV light ({lambda}=254 nm) in a media of 40% water and 60% ethanol, the degradation as well as the regeneration of the hormones was studied with each hormone individually and in the mixture with VitC as a function of the absorbed UV dose, using HPLC. Calculated from the obtained initial yields, the determined regeneration of PRG amounted to 52.7%, for TES to 58.6% and for E1 to 90.9%. The consumption of VitC was determined in the same way. The reported results concerning the regeneration of hormones by the transfer of electrons from an electron donor offer a new, promising method for the therapy with hormones. As a consequence of the regeneration of hormones, a decreased formation of carcinogenic metabolites is expected.

  1. Photo-induced regeneration of hormones by electron transfer processes: Potential biological and medical consequences

    International Nuclear Information System (INIS)

    Getoff, Nikola; Hartmann, Johannes; Schittl, Heike; Gerschpacher, Marion; Quint, Ruth Maria

    2011-01-01

    Based on the previous results concerning electron transfer processes in biological substances, it was of interest to investigate if hormone transients resulting by e.g. electron emission can be regenerated. The presented results prove for the first time that the hormone transients originating by the electron emission process can be successfully regenerated by the transfer of electrons from a potent electron donor, such as vitamin C (VitC). Investigations were performed using progesterone (PRG), testosterone (TES) and estrone (E1) as representatives of hormones. By irradiation with monochromatic UV light (λ=254 nm) in a media of 40% water and 60% ethanol, the degradation as well as the regeneration of the hormones was studied with each hormone individually and in the mixture with VitC as a function of the absorbed UV dose, using HPLC. Calculated from the obtained initial yields, the determined regeneration of PRG amounted to 52.7%, for TES to 58.6% and for E1 to 90.9%. The consumption of VitC was determined in the same way. The reported results concerning the regeneration of hormones by the transfer of electrons from an electron donor offer a new, promising method for the therapy with hormones. As a consequence of the regeneration of hormones, a decreased formation of carcinogenic metabolites is expected.

  2. Low-energy electron-induced chemistry of ethylene on clean and Cl- and D-covered Ag(111)

    International Nuclear Information System (INIS)

    Zhou, X.L.; White, J.M.

    1992-01-01

    The chemistry, induced by 50-eV electrons, of ethylene (C 2 H 4 ) on clean and Cl- and D-covered Ag(111) has been studied. In the absence of electron irradiation, C 2 H 4 is weakly π-bonded and desorbs, with no thermal decomposition, below 170 K. Consistent with π-donation and π-polarization, one monolayer of ethylene lowers the work function by 0.38 eV. Evidence is presented that adsorbed C 2 H 4 , exposed to low doses of electrons, is selectively decomposed to adsorbed H and vinyl (C 2 H 3 ). The latter leads exclusively to 1,3-butadiene (C 4 H 6 ) in subsequent temperature-programmed desorption (TPD). Besides C 4 H 6 , higher doses of electrons lead to acetylene (C 2 H 2 ), precursors to butene and tiny amounts of ethane, but no C 1 or C 3 products. In the presence of Cl, the parent ethylene is stabilized and the amount of C 4 H 6 produced in TPD is enhanced. For ethylene and coadsorbed D, there is, in the absence of electron irradiation, no reaction. With electron irradiation, isotopically labeled dihydrogen and partially deuterated ethylene and ethane form, but there are no C 1 , C 3 , or C 4 products. We propose that bond-specific decomposition, e.g., C-H bond cleavage, to form vinyl occurs when the weakly bound ethylene is ionized by low-energy electrons. That further C-H bond cleavage occurs with much lower cross section and that there is no C-C bond cleavage may result from relatively effective quenching of excited ionic states of the strongly chemisorbed primary product, C 2 H 3 . 28 refs., 8 figs

  3. Nanoscale Soldering of Positioned Carbon Nanotubes using Highly Conductive Electron Beam Induced Gold Deposition

    DEFF Research Database (Denmark)

    Madsen, Dorte Nørgaard; Mølhave, Kristian; Mateiu, Ramona Valentina

    2003-01-01

    We have developed an in-situ method for controlled positioning of carbon nanotubes followed by highly conductive contacting of the nanotubes, using electron beam assisted deposition of gold. The positioning and soldering process takes place inside an Environmental Scanning Electron Microscope (E......-SEM) in the presence of a source of gold-organic precursor gas. Bridges deposited between suspended microelectrodes show resistivities down to 10-4 Ωcm and Transmission Electron Microscopy (TEM) of the deposits reveals a dense core of gold particles surrounded by a crust of small gold nanoparticles embedded...

  4. In situ transmission electron microscopy of light-induced photocatalytic reactions

    DEFF Research Database (Denmark)

    Cavalca, Filippo; Laursen, Anders Bo; Kardynal, Beata

    2012-01-01

    Transmission electron microscopy (TEM) makes it possible to obtain insight into the structure, composition and reactivity of photocatalysts, which are of fundamental interest for sustainable energy research. Such insight can be used for further material optimization. Here, we combine conventional...

  5. Electron irradiation induced reduction of the permittivity in chalcogenide glass (As2S3) thin film

    KAUST Repository

    San Roman Alerigi, Damian

    2013-01-01

    In this paper, we investigate the effect of electron beam irradiation on the dielectric properties of As 2 S 3 chalcogenide glass. By means of low-loss electron energy loss spectroscopy, we derive the permittivity function, its dispersive relation, and calculate the refractive index and absorption coefficients under the constant permeability approximation. The measured and calculated results show a heretofore unseen phenomenon: a reduction in the permittivity of ? 40 %. Consequently a reduction of the refractive index of 20%, hence, suggests a conspicuous change in the optical properties of the material under irradiation with a 300 keV electron beam. The plausible physical phenomena leading to these observations are discussed in terms of the homopolar and heteropolar bond dynamics under high energy absorption. The reported phenomena, exhibited by As 2 S 3-thin film, can be crucial for the development of photonics integrated circuits using electron beam irradiation method. © 2013 American Institute of Physics.

  6. Novel approaches to study low-energy electron-induced damage to DNA oligonucleotides

    International Nuclear Information System (INIS)

    Rackwitz, Jenny; Bald, Ilko; Ranković, Miloš Lj; Milosavljević, Aleksandar R

    2015-01-01

    The novel approach of DNA origami structures as templates for precise quantification of various well- defined oligonucleotides provides the opportunity to determine the sensitivity of complex DNA sequences towards low-energy electrons. (paper)

  7. Electron transfer reactions induced by the triplet state of thiacarbocyanine dimers

    International Nuclear Information System (INIS)

    Chibisov, Alexander K.; Slavnova, Tatyana D.; Goerner, Helmut

    2004-01-01

    The photoinduced electron transfer between either cationic 5,5 ' -dichloro-3,3 ' ,9-triethylthiacarbocyanine (1) or a structurally similar anionic dye (2) and appropriate donors, e.g. ascorbic acid, and acceptors, e.g. methyl viologen, was studied by ns-laser photolysis. In aqueous solution the dyes in the ground state are present as an equilibrated mixture of dimers and monomers, whereas the triplet state is mainly populated from dimers. The triplet states of both dimers and monomers are quenched by electron donors or acceptors and the rate constant for quenching is generally 2-4 times higher for dimers than for monomers. The kinetics of triplet decay and radical formation and decay as a result of primary and secondary electron transfer were analyzed. While the one-electron reduced dimer decays due to back reactions, the one-electron oxidized dimer rapidly dissociates into the monomer and the monomeric dye radical. For the dimeric dye/donor/acceptor systems the primary photoinduced electron transfer occurs either from the donor or to the acceptor yielding the dimeric dye radicals. The one-electron reduced dimer can be efficiently oxidized by acceptors, e.g. the rate constant for reaction of the dimeric dye radical of 1 with methyl viologen (photoreductive pathway of sensitization) is 1.6x10 9 M -1 s -1 . The photooxidative pathway of sensitization is more complicated; after dissociation of the dimeric dye radical, the monomeric dye radical is reduced in a secondary electron transfer from ascorbic acid, e.g. with a rate constant of 1x10 9 M -1 s -1 for 2, yielding the monomer. On increasing the donor concentration the photooxidative pathway of sensitization is switched to a photoreductive one

  8. Electron Beam Induced Mass Loss Dependence on Stained Thin Epon Resin Sections

    Czech Academy of Sciences Publication Activity Database

    Skoupý, Radim; Nebesářová, Jana; Krzyžánek, Vladislav

    2016-01-01

    Roč. 22, S3 (2016), s. 926-927 ISSN 1431-9276 R&D Projects: GA ČR(CZ) GA14-20012S; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 ; RVO:60077344 Keywords : TEM * STEM * EFTEM Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering; JA - Electronics ; Optoelectronics, Electrical Engineering (BC-A) Impact factor: 1.891, year: 2016

  9. Electron beam induced oxygen in YBa2Cu3O7-x superconductors

    International Nuclear Information System (INIS)

    Basu, S.N.; Roy, T.; Mitchell, T.E.; Nastasi, M.

    1989-01-01

    Thin foils of bulk YBa 2 Cu 3 O 7-x (YBCO) superconductors were subjected to electron irradiation in a Transmission Electron Microscope (TEM). The resulting disordering of the oxygen atoms and vacancies in the Cu-O planes was monitored by measuring the splitting of the (110) diffraction spots in the [001] diffraction pattern. Samples were irradiated at 83K with 100, 150, 200 and 300kV electrons. The 100kV electrons did not cause any disordering, even after prolonged irradiation. The results of the higher energy irradiations showed an excellent fit to a disordering model, indicating a lack of radiation assisted ordering at 83K. This was further confirmed by the insensitivity of the disordering to the dose rate of 300kV electrons at 83K. However, at 300K, an increase in the dose rate of 300kV electrons increased the disordering rate, indicating that radiation assisted reordering was occurring at that temperature. 7 refs., 4 figs

  10. Resistivity of thin gold films on mica induced by electron-surface scattering: Application of quantitative scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Robles, Marcelo E.; Gonzalez-Fuentes, Claudio A.; Henriquez, Ricardo; Kremer, German; Moraga, Luis; Oyarzun, Simón; Suarez, Marco Antonio; Flores, Marcos; Munoz, Raul C.

    2012-01-01

    We report a comparison between the resistivity measured on thin gold films deposited on mica, with predictions based upon classical theories of size effects (Drude's, Sondheimer's and Calecki's), as well as predictions based upon quantum theories of electron-surface scattering (the modified theory of Sheng, Xing and Wang, the theory of Tesanovic, Jaric and Maekawa, and that of Trivedi and Aschroft). From topographic images of the surface recorded with a Scanning Tunneling Microscope, we determined the rms roughness amplitude, δ and the lateral correlation length, ξ corresponding to a Gaussian representation of the average height-height autocorrelation function, describing the roughness of each sample in the scale of length set by the Fermi wave length. Using (δ, ξ) as input data, we present a rigorous comparison between resistivity data and predictions based upon the theory of Calecki as well as quantum theoretical predictions without adjustable parameters. The resistivity was measured on gold films of different thickness evaporated onto mica substrates, between 4 K and 300 K. The resistivity data covers the range 0.1 < x(T) < 6.8, for 4 K < T < 300 K, where x(T) is the ratio between film thickness and electron mean free path in the bulk at temperature T. We experimentally identify electron-surface and electron-phonon scattering as the microscopic electron scattering mechanisms giving rise to the macroscopic resistivity. The different theories are all capable of estimating the thin film resistivity to an accuracy better than 10%; however the mean free path and the resistivity characterizing the bulk turn out to depend on film thickness. Surprisingly, only the Sondheimer theory and its quantum version, the modified theory of Sheng, Xing and Wang, predict and increase in resistivity induced by size effects that seems consistent with published galvanomagnetic phenomena also arising from electron-surface scattering measured at low temperatures.

  11. Study of the electron kinetic processes in laser-induced breakdown of electronegative gases over an extended wavelength range

    Science.gov (United States)

    Gamal, Yosr E. E.-D.; Omar, M. M.

    2001-12-01

    A theoretical investigation of laser-induced breakdown of electronegative gases is presented. The formulations are based on an electron cascade model previously developed by Evans and Gamal (J. Phys. D: Appl. Phys. 13 (1980) 1447-1458). This model solves numerically the time-dependent Boltzmann equation simultaneously with a set of rate equations describing the population density of the formed excited states. It includes the possible kinds of interactions between electrons, molecules and photons. Calculations are carried out under the experimental conditions of Davis et al. (Appl. Optics 30 (1991) 4358-4364) where molecular oxygen over a pressure range of 20-760 Torr is irradiated with the first four harmonics of a Nd : YAG laser source at wavelengths 1064, 532, 355 and 266 nm of pulse duration 8.5, 7.5, 6.5 and 5.5 ns, respectively, and peak irradiance varies between 3.6×10 10 and 3.7×10 11 W/cm 2. Computations revealed that the dependence of threshold irradiance on gas pressure is in quite close agreement with those measured by Davis et al. (1991) for the four laser wavelengths considered in this analysis. It is also shown that at laser wavelengths 532 and 266 nm oxygen breakdown is mainly governed by the combined effect of two and three-body attachment loss processes, while for the wavelengths 335and 1064 nm, the three-body attachment process dominates. In addition, calculation of the electron energy distribution function and its parameters, viz, electron density, ionization rate and electron mean energy predicted the importance of the photoionization of excited states as the main electron generation process over the short wavelength range.

  12. Electron emission induced by resonant coherent interaction in ion-surface scattering at grazing incidence

    International Nuclear Information System (INIS)

    Garcia de Abajo, F.J.; Ponce, V.H.; Echenique, P.M.

    1994-01-01

    The resonant coherent interaction of an ion with an oriented crystal surface, under grazing-incidence conditions with respect to a special direction of the crystal, gives rise to electron loss to the continuum from electronic bound states of the ion. The calculations presented below predict large probabilities for electron emission due to this mechanism. The electrons are emitted with well defined energies, expressed in terms of the condition of resonance. Furthermore, the emission takes place around certain preferential directions, which are determined by both the latter condition and the symmetry of the surface lattice. Our calculations for MeV He + ions scattered at a W(001) surface along the left-angle 100 right-angle direction with glancing angle of 0--2 mrad indicate a yield of emission close to 1. Using heavier projectiles, one obtains smaller yields, but still large enough to be measurable in some cases (e.g., ∼0.9 for 53 MeV B 4+ and an angle of incidence of 1 mrad). Besides, the initial bound state is energy shifted due to the interaction with both the crystal potential and the velocity-dependent image potential. This results in a slight shift of the peaks of emission, which suggests a possible spectroscopy for analyzing the dynamical interaction of electronic bound states with solid surfaces

  13. Flirting, Dating, and Breaking up within New Media Environments

    Science.gov (United States)

    Meenagh, Joni

    2015-01-01

    Although romantic and sexual relationships are an important aspect of young people's lives, research on how young people negotiate their love/sex relationships is lacking. New media environments provide a new context within which young people negotiate their love/sex relationships; however, what is negotiated is often not all that different from…

  14. Coping with Break-Ups: Rebound Relationships and Gender Socialization

    Directory of Open Access Journals (Sweden)

    Cassie Shimek

    2014-01-01

    Full Text Available When serious romantic relationships are terminated, partners are faced with convoluted and complex challenges of detachment from their previous partner, negative feelings about the overall situation, and the need to move forward in life. When faced with this relational upheaval, some individuals employ and find relief in superficial or noncommittal rebound relationships, which act as a means for coping with the loss of the previous relationship and the severed emotional attachment to an ex-partner, but which are under studied by empirical researchers. In a study of 201 participants, men were predicted and found to be more likely to enter rebound relationships in the aftermath of a relational termination based on lower levels of social support, more emotional attachment to an ex-partner, and displaying the ludus (or game playing love style. In addition to the measures of these variables, gender socialization and parental investment theory provide further support for the study’s claims. In sum, rebound relationships were employed by men as a distraction from their feelings of emotional attachment for their ex-partner, but also as a source of support and due to inherent ludic characteristics.

  15. Microfluidic droplet generator with controlled break-up mechanism

    KAUST Repository

    Gonzalez, David Conchouso

    2017-04-13

    Droplet generation devices and systems that parallelize droplet generation devices are provided. The droplet generation devices can include a symmetric block-and-break system and a tapered droplet generation zone. The symmetric block-and-break system can include a pair of break channels and a pair of bypass channels symmetrically arranged with respect to the dispersed-phase input channel and the output channel. The droplet generation devices can generate monodisperse droplets with a predefined volume over a range of flow rates, pressures, and fluid properties. The droplet generation devices are therefore capable of parallelization to achieve large-capacity droplet generation, e.g. greater than 1 L/hr, with small overall coefficients of variation.

  16. Energy education: breaking up the rational energy use barriers

    International Nuclear Information System (INIS)

    Dias, R.A.; Mattos, C.R.; Balestieri, J.A.P.

    2004-01-01

    Human development is associated directly or indirectly with the energy use, and because of this the energetic sources were dealt with in the recent past, as fully available to human necessities. The reality shows that the energy availability, considering the non-renewable sources, is limited, and beyond that, the exploration, the processing and the use of energy impose considerable impacts on the environment. There is not a system which operates with no losses and without imposing changes to the environment. Therefore, the energy conservation incorporates the concepts and the actions applied to the research of sustainable balance between nature and the energy availability and use. Such actions can be presented both in the short term, in which the energy system is close to a collapse, or in the medium/long term, in which those responsible for the energy policies are concerned with the structure of the socio-economic development. Such a situation requires more responsibility in the treatment of energy questions, mainly through education, which represents long-term investments. This paper discusses barriers that are present in the projects applied to energy conservation, by making clear that education is one of the best ways to transform the human behavior in for the rational use of energy

  17. Correlations for damage in diffused-junction InP solar cells induced by electron and proton irradiation

    International Nuclear Information System (INIS)

    Yamaguchi, M.; Takamoto, T.; Taylor, S.J.; Walters, R.J.; Summers, G.P.; Flood, D.J.; Ohmori, M.

    1997-01-01

    The damage to diffused-junction n + -p InP solar cells induced by electron and proton irradiations over a wide range of energy from 0.5 to 3 MeV and 0.015 to 20 MeV, respectively, has been examined. The experimental electron and proton damage coefficients have been analyzed in terms of displacement damage dose, which is the product of the particle fluence and the calculated nonionizing energy loss [G. P. Summers, E. A. Burke, R. Shapiro, S. R. Messenger, and R. J. Walters, IEEE Trans. Nucl. Sci. 40, 1300 (1993).] Degradation of InP cells due to irradiation with electrons and protons with energies of more than 0.5 MeV show a single curve as a function of displacement damage dose. Based on the deep-level transient spectroscopy analysis, damage equivalence between electron and proton irradiation is discussed. InP solar cells are confirmed to be substantially more radiation resistant than Si and GaAs-on-Ge cells. copyright 1997 American Institute of Physics

  18. Failure Analysis of a Nickel-Plated Electronic Connector Due to Salt-Induced Corrosion (ENGE 2014).

    Science.gov (United States)

    Lee, Na-Ri; Choi, Hyoung-Seuk; Choi, Duck-Kyun

    2015-10-01

    When electronic connectors in mobile devices are miniaturized, the thickness of plating decreases. However, this thin plating is expected to decrease the life of the connector due to problems with corrosion. In this study, salt spray aging tests were performed on miniaturized nickel-plated stainless steel electronic connectors to observe failure mechanisms in realistic environments. The tests were performed three times using a 5% NaCl solution in an atmosphere of 45 °C; each test included several cycles where one cycle was one 24-h period consisting of 8 h of salt spray and 16 h without salt spray. The nickel-plating layers were periodically observed by electron probe X-ray micro-analyzer, wavelength dispersive spectroscopy, and field-emission scanning electron microscopy to analyze and identify the corrosion mechanism. We found that the primary failure mode of the nickel plating is blistering and delamination. The corrosion mechanism is typically a chain reaction of several corrosion mechanisms: pitting corrosion --> stress corrosion cracking --> hydrogen-induced cracking --> blistering and delamination. Finally, we discuss countermeasures to prevent corrosion of the nickel layer based on the corrosion mechanisms identified in this study.

  19. Fast crystallization of amorphous Gd2Zr2O7 induced by thermally activated electron-beam irradiation

    Science.gov (United States)

    Huang, Zhangyi; Qi, Jianqi; Zhou, Li; Feng, Zhao; Yu, Xiaohe; Gong, Yichao; Yang, Mao; Shi, Qiwu; Wei, Nian; Lu, Tiecheng

    2015-12-01

    We investigate the ionization and displacement effects of an electron-beam (e-beam) on amorphous Gd2Zr2O7 synthesized by the co-precipitation and calcination methods. The as-received amorphous specimens were irradiated under electron beams at different energies (80 keV, 120 keV, and 2 MeV) and then characterized by X-ray diffraction and transmission electron microscopy. A metastable fluorite phase was observed in nanocrystalline Gd2Zr2O7 and is proposed to arise from the relatively lower surface and interface energy compared with the pyrochlore phase. Fast crystallization could be induced by 120 keV e-beam irradiation (beam current = 0.47 mA/cm2). The crystallization occurred on the nanoscale upon ionization irradiation at 400 °C after a dose of less than 1017 electrons/cm2. Under e-beam irradiation, the activation energy for the grain growth process was approximately 10 kJ/mol, but the activation energy was 135 kJ/mol by calcination in a furnace. The thermally activated ionization process was considered the fast crystallization mechanism.

  20. Automated quantum chemistry based molecular dynamics simulations of electron ionization induced fragmentations of the nucleobases Uracil, Thymine, Cytosine, and Guanine.

    Science.gov (United States)

    Grimme, Stefan; Bauer, Christopher Alexander

    2015-01-01

    The gas-phase decomposition pathways of electron ionization (EI)-induced radical cations of the nucleobases uracil, thymine, cytosine, and guanine are investigated by means of mixed quantum-classical molecular dynamics. No preconceived fragmentation channels are used in the calculations. The results compare well to a plethora of experimental and theoretical data for these important biomolecules. With our combined stochastic and dynamic approach, one can access in an unbiased way the energetically available decomposition mechanisms. Additionally, we are able to separate the EI mass spectra of different tautomers of cytosine and guanine. Our method (previously termed quantum chemistry electron ionization mass spectra) reproduces free nucleobase experimental mass spectra well and provides detailed mechanistic in-sight into high-energy unimolecular decomposition processes.

  1. Electron beam induced coloration and luminescence in layered structure of WO3 thin films grown by pulsed dc magnetron sputtering

    International Nuclear Information System (INIS)

    Karuppasamy, A.; Subrahmanyam, A.

    2007-01-01

    Tungsten oxide thin films have been deposited by pulsed dc magnetron sputtering of tungsten in argon and oxygen atmosphere. The as-deposited WO 3 film is amorphous, highly transparent, and shows a layered structure along the edges. In addition, the optical properties of the as-deposited film show a steplike behavior of extinction coefficient. However, the electron beam irradiation (3.0 keV) of the as-deposited films results in crystallization, coloration (deep blue), and luminescence (intense red emission). The above changes in physical properties are attributed to the extraction of oxygen atoms from the sample and the structural modifications induced by electron bombardment. The present method of coloration and luminescence has a potential for fabricating high-density optical data storage device

  2. Mobile interstitial model and mobile electron model of mechano-induced luminescence in coloured alkali halide crystals

    International Nuclear Information System (INIS)

    Chandra, B.P.; Singh, Seema; Ojha, Bharti; Shrivastava, R.G.

    1996-01-01

    A theoretical study is made on the mobile interstitial and mobile electron models of mechano-induced luminescence in coloured alkali halide crystals. Equations derived indicate that the mechanoluminescence intensity should depend on several factors like strain rate, applied stress, temperature, density of F-centres and volume of crystal. The equations also involve the efficiency and decay time of mechanoluminescence. Results of mobile interstitial and mobile electron models are compared with the experimental observations, which indicated that the latter is more suitable as compared to the former. From the temperature dependence of ML, the energy gaps between the dislocation band and ground state of F-centre is calculated which are 0.08, 0.072 and 0.09 eV for KCl, KBr and NaCl crystals, respectively. The theory predicts that the decay of ML intensity is related to the process of stress relaxation in crystals. (author). 33 refs., 5 figs., 1 tab

  3. Protective role of Carica papaya (Linn.) in electron beam radiation induced hematological and cytogenetic damages in Swiss albino mice

    International Nuclear Information System (INIS)

    Yogish Somayaji, T.; Suchetha Kumari, N.

    2014-01-01

    Carica papaya (Linn.) is known to possess various biomedical applications. It has remarkable antioxidant properties. The main objective of the study was to evaluate the leaf extracts of Carica papaya (Linn.) on hematologic and cytogenetic changes occurring due to irradiation of mice to sub-lethal doses of Electron Beam Radiation (EBR). Analysis of hematological changes occurring due to irradiation of mice to sub-lethal doses of EBR, and the effects of Carica papaya (Linn.) extract on the same. The Assessment of hematopoietic stress by spleen colony forming unit and spleen body weight index. The analysis of cell proliferation and immunomodulation with response to the effects of Carica papaya (Linn.) extract by estimation of IL-6. The estimation of serum total antioxidants, lipid peroxidation and analyzing the activities of enzymes like SOD, ALP, and AST. Male Swiss albino mice were fed orally with papaya aqueous leaf extract for 15 days. They were irradiated with a whole body dose of 6 Gy Electron Beam radiation. The mice were dissected for liver, kidney, bone marrow, spleen and brain. The hematological studies were done using blood cell count in an automated cell counter. The biochemical estimations like urea, creatinine, SGOT, SGPT, Total Protein, Albumin, Bilirubin were done using the serum and homogenates. The total antioxidant capacity, the antioxidant enzymes were estimated. The Interleukin-6 levels were estimated in serum to assess immune modulation. The results show a decrease in the hematological parameters in radiated animals. The papaya treated groups have shown modulation in the hematological parameters. The extract has also reduced the suppression of the bone marrow induced by radiation. The radiation induced liver damage is also reduced in papaya treated groups. The aqueous extract of Carica papaya (Linn.) has shown protective effects in electron beam radiation induced tissue damages in Swiss Albino mice (author)

  4. Electronic communication between two [10]cycloparaphenylenes and bisazafullerene (C59N)2 induced by cooperative complexation.

    Science.gov (United States)

    Rio, Jérémy; Beeck, Sebastian; Rotas, Georgios; Ahles, Sebastian; Jacquemin, Denis; Tagmatarchis, Nikos; Ewels, Chris; Wegner, Hermann Andreas

    2018-03-23

    The complex of [10]cycloparaphenylene ([10]CPP) with bisazafullerene (C59N)2 is investigated experimentally and computationally. Two [10]CPP rings are bound to the dimeric azafullerene giving [10]CPP⊃(C59N)2⊂[10]CPP. Photophysical and redox properties support an electronic interaction between the com-ponents especially with the second [10]CPP bound. Unlike [10]CPP⊃C60, where there is negligible electronic communication bet¬ween the two species, upon photoexcitation a partial charge trans¬fer phenomenon is revealed between [10]CPP and (C59N)2 reminiscent of CPP encapsulated metallofullerenes. Such an alternative electron-rich fullerene species demonstrates C60-like ground-state properties and metallofullerene-like excited-state properties opening new avenues for construction of functional supramolecular architectures with organic materials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Removing Contamination-Induced Reconstruction Artifacts from Cryo-electron Tomograms

    Science.gov (United States)

    Fernandez, Jose-Jesus; Laugks, Ulrike; Schaffer, Miroslava; Bäuerlein, Felix J.B.; Khoshouei, Maryam; Baumeister, Wolfgang; Lucic, Vladan

    2016-01-01

    Imaging of fully hydrated, vitrified biological samples by electron tomography yields structural information about cellular protein complexes in situ. Here we present a computational procedure that removes artifacts of three-dimensional reconstruction caused by contamination present in samples during imaging by electron microscopy. Applying the procedure to phantom data and electron tomograms of cellular samples significantly improved the resolution and the interpretability of tomograms. Artifacts caused by surface contamination associated with thinning by focused ion beam, as well as those arising from gold fiducial markers and from common, lower contrast contamination, could be removed. Our procedure is widely applicable and is especially suited for applications that strive to reach a higher resolution and involve the use of recently developed, state-of-the-art instrumentation. PMID:26743046

  6. Pulse electron beam-induced synthesis of CdTe printed films

    International Nuclear Information System (INIS)

    Houng, M.P.; Fu, S.L.; Wu, T.S.; Leu, J.T.; Cheng, K.Y.

    1987-01-01

    In an attempt to produce a high quality single crystal CdTe film with enhanced electrical properties, screen printed Cd + Te films were prepared on an aluminium oxide substrate and then irradiated with a pulsed electron beam over the energy range 12-15 KeV. Some samples were also vacuum annealed from 410-620 0 C after irradiation. The films were characterized by x-ray diffraction, scanning electron microscopy and photoluminescence. This showed that film quality and uniformity were limited by electron beam heating, although improvements can be made by vacuum annealing. Furthermore, only polycrystalline films were produced, possibly due to a too short pulse duration and the use of a polycrystalline substrate. (U.K.)

  7. Neutron-induced electronic failures around a high-energy linear accelerator

    International Nuclear Information System (INIS)

    Kry, Stephen F.; Johnson, Jennifer L.; White, R. Allen; Howell, Rebecca M.; Kudchadker, Rajat J.; Gillin, Michael T.

    2011-01-01

    Purpose: After a new in-vault CT-on-rails system repeatedly malfunctioned following use of a high-energy radiotherapy beam, we investigated the presence and impact of neutron radiation on this electronic system, as well as neutron shielding options. Methods: We first determined the CT scanner's failure rate as a function of the number of 18 MV monitor units (MUs) delivered. We then re-examined the failure rate with both 2.7-cm-thick and 7.6-cm-thick borated polyethylene (BPE) covering the linac head for neutron shielding. To further examine shielding options, as well as to explore which neutrons were relevant to the scanner failure, Monte Carlo simulations were used to calculate the neutron fluence and spectrum in the bore of the CT scanner. Simulations included BPE covering the CT scanner itself as well as covering the linac head. Results: We found that the CT scanner had a 57% chance of failure after the delivery of 200 MUs. While the addition of neutron shielding to the accelerator head reduced this risk of failure, the benefit was minimal and even 7.6 cm of BPE was still associated with a 29% chance of failure after the delivery of 200 MU. This shielding benefit was achieved regardless of whether the linac head or CT scanner was shielded. Additionally, it was determined that fast neutrons were primarily responsible for the electronic failures. Conclusions: As illustrated by the CT-on-rails system in the current study, physicists should be aware that electronic systems may be highly sensitive to neutron radiation. Medical physicists should therefore monitor electronic systems that have not been evaluated for potential neutron sensitivity. This is particularly relevant as electronics are increasingly common in the therapy vault and newer electronic systems may exhibit increased sensitivity.

  8. Pigment colors printing on cotton fabrics by surface coating induced by electron beam and thermal curing

    International Nuclear Information System (INIS)

    El-Naggar, Abdel Wahab M.; Zohdy, Maged H.; Said, Hossam M.; El-Din, Mahmoud S.; Noval, Dalia M.

    2005-01-01

    Cotton fabrics were coated from one surface with different pigment colors incorporated in formulations containing ethylene glycol (EG), methyl methacrylate (MMA) and poly(methyl methacrylate) (PMMA) oligomer as a base material. The coated fabrics were exposed to various doses of accelerated electrons generated from the 1.5 MeV (25 kW) electron beam accelerator machine. In order to find the suitable conditions that afford the highest performance of pigment printing, the effect of irradiation dose and formulation composition on the color strength of the printed fabrics was investigated. The durability of the printed fabrics in terms of color fastness, tensile mechanical, crease resistance and water absorption was also studied. The results of pigment printing by electron beam irradiation was compared with the conventional thermal printing method with the same pigment colors involving the use of pastes containing binder and thickener systems. It was found that cotton fabrics printed with the pigment colors under the effect of electron beam irradiation displayed higher color strength than those fabrics printed by the conventional thermal fixation at equal pigment color ratios. In this regard, the color strength on cotton fabrics printed with the Imperon violet, blue and yellow pigment colors was 85.2, 75.4 and 91.3 in the case of printing with electron beam and 63.5, 46.0 and 50.2 in the case of thermal curing, respectively. The results showed that the pigment printing by electron beam or thermal curing improves the crease recovery and mechanical properties of cotton fabrics and exhibited comparable durability properties in terms of washing, rubbing and handling

  9. Electron- and photon-induced plasmonic excitations in two-dimensional silver nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Hoang, C. V.; Rana, M. [International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Nagao, T., E-mail: Nagao.Tadaaki@nims.go.jp [International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2014-06-23

    Plasmons are the quasi particles of collective oscillations of electrons and form the basis of plasmonics and optical metamaterials. We combined electron spectroscopy and optical spectroscopy techniques to study plasmons in atomically smooth Ag films and in epitaxial Ag nanodisks to map the momentum-energy dispersion curves of the two-dimensional (2D) sheet plasmon and the quasi-2D plasmons to clarify the essential differences between them. Our experimental results combined with the results of numerical electromagnetic simulations showed that the bulk-like nature of the silver plasmon starts in layers that are only two atoms thick.

  10. Identification of defects in GaAs induced by 1 MeV electron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lai, S.T.; Nener, B.D.; Faraone, L.; Nassibian, A.G. [Western Australia Univ., Nedlands, WA (Australia); Hotchkis, M.A.C. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1993-12-31

    This paper shows that 1 MeV electron irradiation on n-type vapor phase epitaxial (VPE) GaAs creates three electron traps E1, E2 and EL6, and results in the splitting of the EL2 center into two levels EL2-A and EL2-B. A 15 minutes isochronal anneal results in the annihilation of the E1 and E2 traps, a reduction in EL6 trap concentration, and the return of EL2 to a single level EL2-A. A defect model is outlined which correlates with the observed results. 4 refs., 2 tabs., 3 figs.

  11. Microwave-induced co-tunneling in single electron tunneling transistors

    DEFF Research Database (Denmark)

    Ejrnaes, M.; Savolainen, M.; Manscher, M.

    2002-01-01

    on rubber bellows. Cross-talk was minimized by using individual coaxial lines between the sample and the room temperature electronics: The co-tunneling experiments were performed at zero DC bias current by measuring the voltage response to a very small amplitude 2 Hz current modulation with the gate voltage......The influence of microwaves on the co-tunneling in single electron tunneling transistors has been investigated as function of frequency and power in the temperature range from 150 to 500 mK. All 20 low frequency connections and the RF line were filtered, and the whole cryostat was suspended...

  12. Optical-phonon-induced frictional drag in coupled two-dimensional electron gases

    DEFF Research Database (Denmark)

    Hu, Ben Yu-Kuang

    1998-01-01

    The role of optical phonons in frictional drag between two adjacent but electrically isolated two-dimensional electron gases is investigated. Since the optical phonons in III-V materials have a considerably larger coupling to electrons than acoustic phonons (which are the dominant drag mechanism...... group velocity at the Brillouin zone center, and (ii) the typical momentum transfer for an optical-phonon-mediated scattering is relatively large. These considerations make optical-phonon-mediated drag difficult to see in single-subband GaAs systems, but it may be possible to see the effect in double...

  13. Orientational acoustic emission induced by electrons moving near a crystallographic axis in tungsten

    International Nuclear Information System (INIS)

    Alejnik, A.N.; Vorob'ev, S.A.; Zabaev, V.N.; Il'in, S.I.; Kalinin, B.N.; Potylitsyn, A.P.

    1988-01-01

    The measurement results of oriented acoustic irradiation of electrons with E 0 =900 MeV energies during their axial (along the direction) motion in tungsten monocrystal of 0.29 mm thickness are presented. The model describing the excitation of elastic waves in crystals as the consequence of the momentum transferred to the crystal by electrons during their motion near the axis is suggested. The model describes quite fully main laws of oriented acoustic irradiation. It permits to receive the information about the potential of the atom chain

  14. Sputter-induced formation of an electron accumulation layer in In0.52Al0.48As

    Science.gov (United States)

    Maslar, J. E.; Bohn, P. W.; Agarwala, S.; Adesida, I.; Caneau, C.; Bhat, R.

    1994-06-01

    Ar-sputtering of In0.52Al0.48As was investigated with room-temperature Raman and photoluminescence spectroscopy. A clear increase of carrier density in the near-surface region was observed in the Raman spectra. The PL intensity was found to depend in a complex way on plasma self-bias potential, incident laser irradiance, and InAlAs doping level, indicating that the recombination mechanisms dominating the PL response differ with changing experimental conditions. The observed trends can be explained by sputter-induced formation of an electron accumulation layer in the near-surface region.

  15. Electron beam-induced mass transport in As–Se thin films: compositional dependence and glass network topological effects

    International Nuclear Information System (INIS)

    Trunov, M L; Cserháti, C; Lytvyn, P M; Kaganovskii, Yu; Kökényesi, S

    2013-01-01

    Electron beam (e-beam)-induced changes of surface profile morphology in As c Se 1−c (0.2 0.2 Se 0.8 are connected with lateral mass transport, which increases drastically near rigidity transition, i.e. at a coordination number r ∼ 2.2 of the glass structures when the rigidity starts to percolate through the structure. The model of the process, which reflects the compositional dependence of the stimulated mass transport, is presented. (paper)

  16. Preparation of New Adsorbent Containing Hydroxamic Acid Groups by Electron Beam-Induced Grafting for Metal Ion Adsorption

    International Nuclear Information System (INIS)

    Suwanmala, Phiriyatorn; Hoshina, Hiroyuki; Seko, Noriaki; Tamada, Masao

    2007-08-01

    Full text: A new adsorbent containing hydroxamic acid groups was synthesized by electron beam-induced graft copolymerization of methyl acrylate (MA) onto nonwoven fabric composed of polyethylene-coated polypropylene fiber. Conversion of ester groups of the grafted copolymer into the hydroxamic groups was performed by treatment with an alkaline solution of hydroxylamine (HA). Adsorbent containing hydroxamic acid groups can adsorb 99% of UO2 2+ , 98% of V5+, 97% of Pb2+ and 96% of Al3+ at pH, 5, 4, 6, and 4, respectively, after coming into contact with 100 ppb metal solution for 24 h

  17. Protective effect of Asparagus racemosus root extract against lethal total - body electron beam radiation induced damage in Swiss albino mice

    International Nuclear Information System (INIS)

    Sharmila, K.P.; Bhandary, B. Satheesh Kumar; Suchetha Kumari, N.; Bhat, Vadish S.; Shetty, Jayaram; Peter, Alex John; Jose, Jerish M.; Fernandes, Ronald

    2016-01-01

    To investigate the protective effect of Asparagus Racemosus Root ethanolic extract (ARE) in Swiss albino mice against acute lethal total - body Electron beam irradiation. Swiss Albino mice were used for the assessment of radiation induced sickness and 30 day survival analysis. Survival studies were determined using the Kaplan-Meier survival curves. The maximum survival was observed in the experimental mice pretreated with 200 mg/kg.b.wt. of ARE which also reduced the radiation sickness characteristics. This dose was considered as an optimal dose for radioprotection. Treatment of mice with ARE before irradiation delayed the onset of mortality as compared with the untreated irradiated controls. Present findings demonstrate the potential of ARE in mitigating radiation-induced mortality, which may be attributed to its free radical scavenging and increased antioxidant potential

  18. Eliminating the microbunching-instability-induced sideband in a soft x-ray self-seeding free-electron laser

    Science.gov (United States)

    Zhang, Kaiqing; Zeng, Li; Qi, Zheng; Feng, Chao; Wang, Dong

    2018-02-01

    Soft x-ray self-seeding has been proved to be a feasible method to improve the longitudinal coherence of high gain free-electron laser. However, a pedestal-like sideband in the spectrum has been observed in the experiment, which generally limits the purity of the radiation pulse and the user's application. The previous theoretical study indicates that the pedestal-like sideband is mainly induced by microbunching instability generated from LINAC. In this paper, three dimensional simulations have been performed to confirm the analytical results and show the formation process of the spectral sideband. A probable method is proposed to eliminate the pedestal-like sideband by simply inserting a magnetic chicane before the self-seeding FEL undulator. Theoretical and numerical simulations have been performed and the results show that the proposed method can efficiently eliminate the microbunching-instability-induced sideband in a soft x-ray self-seeding FEL.

  19. Ultraviolet radiation and nanoparticle induced intracellular free radicals generation measured in human keratinocytes by electron paramagnetic resonance spectroscopy.

    Science.gov (United States)

    Rancan, F; Nazemi, B; Rautenberg, S; Ryll, M; Hadam, S; Gao, Q; Hackbarth, S; Haag, S F; Graf, C; Rühl, E; Blume-Peytavi, U; Lademann, J; Vogt, A; Meinke, M C

    2014-05-01

    Several nanoparticle-based formulations used in cosmetics and dermatology are exposed to sunlight once applied to the skin. Therefore, it is important to study possible synergistic effects of nanoparticles and ultraviolet radiation. Electron paramagnetic resonance spectroscopy (EPR) was used to detect intracellular free radicals induced by ultraviolet B (UVB) radiation and amorphous silica nanoparticle and to evaluate the influence of nanoparticle surface chemistry on particle cytotoxicity toward HaCaT cells. Uncoated titanium dioxide nanoparticles served as positive control. In addition, particle intracellular uptake, viability, and induction of interleukin-6 were measured. We found that photo-activated titanium dioxide particles induced a significant amount of intracellular free radicals. On the contrary, no intracellular free radicals were generated by the investigated silica nanoparticles in the dark as well as under UVB radiation. However, under UVB exposure, the non-functionalized silica nanoparticles altered the release of IL-6. At the same concentrations, the amino-functionalized silica nanoparticles had no influence on UVB-induced IL-6 release. EPR spectroscopy is a useful technique to measure nanoparticle-induced intracellular free radicals. Non-toxic concentrations of silica particles enhanced the toxicity of UVB radiation. This synergistic effect was not mediated by particle-generated free radicals and correlated with particle surface charge and intracellular distribution. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Large flexibility of high aspect ratio carbon nanostructures fabricated by electron-beam-induced deposition

    Energy Technology Data Exchange (ETDEWEB)

    Beard, J D; Gordeev, S N, E-mail: jdb28@bath.ac.uk [Department of Physics, University of Bath, Bath BA2 7AY (United Kingdom)

    2010-11-26

    The mechanical properties of free-standing electron beam deposited amorphous carbon structures have been studied using atomic force microscopy. The fabricated carbon blades are found to be extraordinarily flexible, capable of undergoing vertical deflection up to {approx} 75% of their total length without inelastic deformation. The elastic bending modulus of these structures was calculated to be 28 {+-} 10 GPa.

  1. Electron emission induced by atomic collisions in gaseous targets and solids

    International Nuclear Information System (INIS)

    Meckbach, W.

    1988-01-01

    In this work, it is considered only the process of single collision with gaseous targets. The possible inelastic processes are: excitation and ionization of both, target and incident beam. The attention was concentrated to the processes of direct ionization which may give rise to electron emission. (A.C.A.S.) [pt

  2. Dissociative electron attachment and anion-induced dimerization in pyruvic acid

    Czech Academy of Sciences Publication Activity Database

    Zawadzki, Mateusz; Ranković, Miloš; Kočišek, Jaroslav; Fedor, Juraj

    2018-01-01

    Roč. 20, č. 10 (2018), s. 6838-6844 ISSN 1463-9076 R&D Projects: GA ČR GA17-04844S; GA ČR GJ16-10995Y Institutional support: RVO:61388955 Keywords : pyruvic acid * electron attachment * dimerization Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.123, year: 2016

  3. Electron dynamics in CaB6 induced by one- and two-color femtosecond laser

    International Nuclear Information System (INIS)

    Jiao, Y.L.; Wang, F.; Hong, X.H.; Su, W.Y.; Chen, Q.H.; Zhang, F.S.

    2013-01-01

    We simulate nonlinear electron dynamics in CaB 6 crystal within the framework of time-dependent density functional theory (TDDFT) under one-color femtosecond laser fields (400 nm, 800 nm) and two-color cases (400 nm+800 nm) with different relative phases of ϕ=0, ϕ=π/4, ϕ=π/2. The time-dependent Kohn–Sham equation (TDKS) is solved in real-time and real-space evolution scheme. We investigate the energy absorption and the electron excitation of CaB 6 crystal in detail. Besides, the electron density distributions and occupations are shown after each external field ends. Computational results indicate that for one-color case, the excitation behaviors are distinct due to the different frequencies; for two-color laser, we adjust the phase and obtain the asymmetric field, which causes the change of the dynamics response comparing with the symmetric field. At the end of laser, the electron occupation is broadly distributed in the energy range of 2.4–42.4 eV, which means a high excitation rate in the narrow-gap semiconductor under intense laser field. The occurrence of the breakdown is also checked for each case in the Letter.

  4. Electron beam induced modifications in flexible biaxially oriented polyethylene terephthalate sheets: Improved mechanical and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhary, N. [Accelerator & Pulse Power Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Koiry, S.P. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Singh, A., E-mail: asb_barc@yahoo.com [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Tillu, A.R. [Accelerator & Pulse Power Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Jha, P.; Samanta, S.; Debnath, A.K. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Aswal, D.K., E-mail: dkaswal@yahoo.com [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Mondal, R.K. [Radiation Technology Development Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Acharya, S.; Mittal, K.C. [Accelerator & Pulse Power Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India)

    2017-03-01

    In the present work, we have studied the effects of electron beam irradiation (with dose ranging from 2 to 32 kGy) on mechanical and electrical properties of biaxially oriented polyethylene terephthalate (BOPET) sheets. The sol-gel analysis, Fourier transformation infra-red (FTIR), X-ray photoelectron spectroscopy (XPS) characterizations of the irradiated BOPET sheets suggest partial cross-linking of PET chains through the diethylene glycol (DEG). The mechanical properties of BOPET, such as, tensile strength, Young's modulus and electrical resistivity shows improvement with increasing dose and saturate for doses >10 kGy. The improved mechanical properties and high electrical resistivity of electron beam modified BOPET sheets may have additional advantages in applications, such as, packaging materials for food irradiation, medical product sterilization and electronic industries. - Graphical abstract: Irradiation of BOPET by electron beam leads to the formation of diethylene glycol that crosslink's the PET chains, resulting in improved mechanical properties and enhanced electrical resistivity. - Highlights: • BOPET exhibit improved tensile strength/Young's modulus after e-beam exposure. • Electrical resistivity of BOPET increases after e-beam exposure. • Cross-linking of PET chains through diethylene glycol was observed after e-beam exposure.

  5. Threshold velocity in the production of convoy electrons induced by protons crossing thin films

    International Nuclear Information System (INIS)

    Suarez, S.; Bernardi, G.

    1988-01-01

    In this work, results are presented for the measurements of convoy electrons Y (Vp) in function of velocity Vp of the emerging protons of the surface in the energy range.4 2 ), aluminium (180A) and gold (150A) using coaxial cylindric spectrometer. (A.C.A.S.) [pt

  6. Briefly on electronic excitation induced by radiation in a molecular target

    International Nuclear Information System (INIS)

    Bednar, J.

    1985-01-01

    Characteristic microscopic features of the absorption of photons and ionizing radiation by isolated molecules are called to mind of chemists and biologists. The elementary process of induction of electronic excitation localized on a single molecule has important bearing on collective excitation in condensed biological matter. (author)

  7. Cold-induced imbibition damage of lettuce embryos: A study using cryo-scanning electron microscopy

    NARCIS (Netherlands)

    Nijsse, J.; Walther, P.; Hoekstra, F.

    2004-01-01

    The impact of rehydration on a multicellular organism was studied in lettuce (Lactuca sativa L.) embryos, using cryo-scanning electron microscopy (cryo-SEM). Naked embryos were sensitive to imbibitional stress, whereas embryos with an intact, thick-walled endosperm were not. Imbibitional injury to

  8. Computational micromechanics analysis of electron hopping and interfacial damage induced piezoresistive response in carbon nanotube-polymer nanocomposites

    International Nuclear Information System (INIS)

    Chaurasia, A K; Seidel, G D; Ren, X

    2014-01-01

    Carbon nanotube (CNT)-polymer nanocomposites have been observed to exhibit an effective macroscale piezoresistive response, i.e., change in macroscale resistivity when subjected to applied deformation. The macroscale piezoresistive response of CNT-polymer nanocomposites leads to deformation/strain sensing capabilities. It is believed that the nanoscale phenomenon of electron hopping is the major driving force behind the observed macroscale piezoresistivity of such nanocomposites. Additionally, CNT-polymer nanocomposites provide damage sensing capabilities because of local changes in electron hopping pathways at the nanoscale because of initiation/evolution of damage. The primary focus of the current work is to explore the effect of interfacial separation and damage at the nanoscale CNT-polymer interface on the effective macroscale piezoresistive response. Interfacial separation and damage are allowed to evolve at the CNT-polymer interface through coupled electromechanical cohesive zones, within a finite element based computational micromechanics framework, resulting in electron hopping based current density across the separated CNT-polymer interface. The macroscale effective material properties and gauge factors are evaluated using micromechanics techniques based on electrostatic energy equivalence. The impact of the electron hopping mechanism, nanoscale interface separation and damage evolution on the effective nanocomposite electrostatic and piezoresistive response is studied in comparison with the perfectly bonded interface. The effective electrostatic/piezoresistive response for the perfectly bonded interface is obtained based on a computational micromechanics model developed in the authors’ earlier work. It is observed that the macroscale effective gauge factors are highly sensitive to strain induced formation/disruption of electron hopping pathways, interface separation and the initiation/evolution of interfacial damage. (paper)

  9. Management of amiodarone-induced thyrotoxicosis in Latin America: an electronic survey

    NARCIS (Netherlands)

    Diehl, Leandro Arthur; Romaldini, João Hamilton; Graf, Hans; Bartalena, Luigi; Martino, Enio; Albino, Claudio Cordeiro; Wiersinga, Wilmar M.

    2006-01-01

    OBJECTIVE: To assess diagnostic and therapeutic approaches to amiodarone-induced thyrotoxicosis (AIT) among members of the Latin American Thyroid Society (LATS). METHODS: LATS members responded to an online questionnaire that presented an index case (a 62-year-old man on amiodarone, with thyrotoxic

  10. Visualization of alcohol-induced rhabdomyolysis: a correlative radiotracer, histochemical, and electron-microscopic study

    International Nuclear Information System (INIS)

    Silberstein, E.B.; Bove, K.E.

    1979-01-01

    Technetium-99m diphosphonate was used to visualize the extent of alcohol-induced rhabdomyolysis and its resolution. Transient secondary hyperparathyroidism was documented. Histological and biochemical analyses of skeletal muscle obtained at biopsy 6 days postscan and 9 days after the onset of the illness did not show abnormal calcium content

  11. Quantitative determination of copper in a glass matrix using double pulse laser induced breakdown and electron paramagnetic resonance spectroscopic techniques.

    Science.gov (United States)

    Khalil, Ahmed A I; Morsy, Mohamed A

    2016-07-01

    A series of lithium-lead-borate glasses of a variable copper oxide loading were quantitatively analyzed in this work using two distinct spectroscopic techniques, namely double pulse laser induced breakdown spectroscopy (DP-LIBS) and electron paramagnetic resonance (EPR). DP-LIBS results measured upon a combined nanosecond lasers irradiation running at 266nm and 1064nm pulses of a collinear configuration directed to the surface of borate glass samples with a known composition. This arrangement was employed to predict the electron's temperature (Te) and density (Ne) of the excited plasma from the recorded spectra. The intensity of elements' responses using this scheme is higher than that of single-pulse laser induced breakdown spectroscopy (SP-LIBS) setup under the same experimental conditions. On the other hand, the EPR data shows typical Cu (II) EPR-signals in the borate glass system that is networked at a distorted tetragonal Borate-arrangement. The signal intensity of the Cu (II) peak at g⊥=2.0596 has been used to quantify the Cu-content accurately in the glass matrix. Both techniques produced linear calibration curves of Cu-metals in glasses with excellent linear regression coefficient (R(2)) values. This study establishes a good correlation between DP-LIBS analysis of glass and the results obtained using EPR spectroscopy. The proposed protocols prove the great advantage of DP-LIBS system for the detection of a trace copper on the surface of glasses. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Evaluation of Ultrasound-Induced Damage to Escherichia coli and Staphylococcus aureus by Flow Cytometry and Transmission Electron Microscopy.

    Science.gov (United States)

    Li, Jiao; Ahn, Juhee; Liu, Donghong; Chen, Shiguo; Ye, Xingqian; Ding, Tian

    2016-01-08

    As a nonthermal sterilization technique, ultrasound has attracted great interest in the field of food preservation. In this study, flow cytometry and transmission electron microscopy were employed to investigate ultrasound-induced damage to Escherichia coli and Staphylococcus aureus. For flow cytometry studies, single staining with propidium iodide (PI) or carboxyfluorescein diacetate (cFDA) revealed that ultrasound treatment caused cell death by compromising membrane integrity, inactivating intracellular esterases, and inhibiting metabolic performance. The results showed that ultrasound damage was independent of initial bacterial concentrations, while the mechanism of cellular damage differed according to the bacterial species. For the Gram-negative bacterium E. coli, ultrasound worked first on the outer membrane rather than the cytoplasmic membrane. Based on the double-staining results, we inferred that ultrasound treatment might be an all-or-nothing process: cells ruptured and disintegrated by ultrasound cannot be revived, which can be considered an advantage of ultrasound over other nonthermal techniques. Transmission electron microscopy studies revealed that the mechanism of ultrasound-induced damage was multitarget inactivation, involving the cell wall, cytoplasmic membrane, and inner structure. Understanding of the irreversible antibacterial action of ultrasound has great significance for its further utilization in the food industry. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  13. Electron-beam induced damage in thin insulating films on compound semiconductors. M.S. Thesis, 1988

    Science.gov (United States)

    Pantic, Dragan M.

    1989-01-01

    Phosphorus rich plasma enhanced chemical vapor deposition (PECVD) of silicon nitride and silicon dioxide films on n-type indium phosphide (InP) substrates were exposed to electron-beam irradiation in the 5 to 40 keV range for the purpose of characterizing the damage induced in the dielectric. The electron-beam exposure was on the range of 10(exp -7) to 10(exp -3) C/sq cm. The damage to the devices was characterized by capacitance-voltage (C-V) measurements of the metal insulator semiconductor (MIS) capacitors. These results were compared to results obtained for radiation damage of thermal silicon dioxide on silicon (Si) MOS capacitors with similar exposures. The radiation induced damage in the PECVD silicon nitride films on InP was successfully annealed out in an hydrogen/nitrogen (H2/N2) ambient at 400 C for 15 min. The PECVD silicon dioxide films on InP had the least radiation damage, while the thermal silicon dioxide films on Si had the most radiation damage.

  14. Multi-channel Andreev reflection in Co-W nanocontacts fabricated using focused electron/ion beam induced deposition.

    Science.gov (United States)

    Sharma, N; Vugts, P; Daniels, C; Keuning, W; Kohlhepp, J T; Kurnosikov, O; Koopmans, B

    2014-12-12

    We report multi-channel electron transport in nano-contacts fabricated using focused electron beam induced deposited (FEBID) cobalt and focused ion beam induced deposited (FIBID) tungsten. Anomalous Andreev reflection (AR) effect is observed to which the conventional Blonder-Tinkham-Klapwijk (BTK) fit cannot be applied. In specific, we have observed multiple number of shoulders near the AR peak, whose origin is unknown in literature. We explain this effect based on a simple model that takes into account the material properties of the FIBID grown W superconductor, as well as the specific interface properties that are an outcome of using FEBID/FIBID as a fabrication technique. We show that numerical calculations using the BTK approximation based on the consideration of multiple channels generate similar shoulders as we observed in the AR experiments. Electrical measurements and x-ray photoemission spectroscopy carried out on FIBID W deposits puts additional evidence towards multi-channel current transport occuring at the interface of the nanocontacts.

  15. Grafting and polymerisation processes induced by electron beams for antistatic treatment and hydrophilation of polyester textiles with polyethylene glycol dimethacrylates

    International Nuclear Information System (INIS)

    Clauss, B.

    1986-01-01

    According to dosimetric measurements on various textiles, the penetration behaviour of accelerated electrons in textile substrates corresponds to that found for homogeneous foils. A clear relationship is given between depth of penetration and degree of ionisation. Infrared spectroscopic investigation of the homopolymerisation of polyethylene glycol dimethacrylates induced by radiation makes it clear that cross-linked polymers are formed if the dose is increased. This effect can be supported by the addition of multi-functional acrylates. The measurement of bending stiffness proved to be a useful method for distinguishing between homopolymers and grafted polymers. It was found during comparative measurements on glass fibre and polyester weaves that methacrylates can only be changed to polyesters at a high dose (100 kGy). In the treatment of polyester textiles induced by electron beams, the length of the ethylene glycol chain in the monomer proved to be an important factor. With increasing length of chain, better degrees of fixing, better antistatic effects and better cross-linking properties are found. The limit is reached at a chain length of 12. The appropriate monomer (polyethylene glycol-600-dimethacrylate) gives surfaces resistances of 10 11 ohms. The spread of a drop of water on the textile surface occurs in less than 2 seconds. The antistatic effect of the polymer is based on water adsorption at the textile surface. (orig.) [de

  16. Investigation of metal coatings for the free electron laser

    International Nuclear Information System (INIS)

    Scott, M.L.; Arendt, P.N.; Springer, R.W.; Cordi, R.C.; McCreary, W.J.

    1985-01-01

    We are investigating the deposition and characteristics of metal coatings for use in environments such as the Free Electron Laser where the radiation resistance of metal coatings could prove to be of great benefit. We have concentrated our initial efforts on silver laminate coatings due to the high reflectance of silver at 1 micron wavelength. Our initial laminate coatings have utilized thin layers of titanium oxide to break up the columnar structure of the silver during electron-beam deposition on fused silica substrates. Our initial results on equal coating thickness samples indicate an improvement in damage threshold that ranges from 1.07 to 1.71 at 351 nm

  17. Electron-induced hydrogen loss in uracil in a water cluster environment

    International Nuclear Information System (INIS)

    Smyth, M.; Kohanoff, J.; Fabrikant, I. I.

    2014-01-01

    Low-energy electron-impact hydrogen loss due to dissociative electron attachment (DEA) to the uracil and thymine molecules in a water cluster environment is investigated theoretically. Only the A ′ -resonance contribution, describing the near-threshold behavior of DEA, is incorporated. Calculations are based on the nonlocal complex potential theory and the multiple scattering theory, and are performed for a model target with basic properties of uracil and thymine, surrounded by five water molecules. The DEA cross section is strongly enhanced when the attaching molecule is embedded in a water cluster. This growth is due to two effects: the increase of the resonance lifetime and the negative shift in the resonance position due to interaction of the intermediate negative ion with the surrounding water molecules. A similar effect was earlier found in DEA to chlorofluorocarbons

  18. Electron transfer mechanism and photochemistry of ferrioxalate induced by excitation in the charge transfer band.

    Science.gov (United States)

    Chen, Jie; Zhang, Hua; Tomov, Ivan V; Rentzepis, Peter M

    2008-03-17

    The photoredox reaction of ferrioxalate after 266/267 nm excitation in the charge transfer band has been studied by means of ultrafast extended X-ray absorption fine structure (EXAFS) analysis, optical transient spectroscopy, and quantum chemistry calculations. The Fe-O bond length changes combined with the transient spectra and kinetics have been measured and in combination with ultrahigh frequency density functional theory (UHF/DFT) calculations are used to determine the photochemical mechanism for the Fe(III) to Fe(II) redox reaction. The present data and the results obtained with 266/267 nm excitations strongly suggest that the primary reaction is the dissociation of the Fe-O bond before intramolecular electron transfer occurs. Low quantum yield electron photodetachment from ferrioxalate has also been observed.

  19. Intense source of spin-polarized electrons using laser-induced optical pumping

    International Nuclear Information System (INIS)

    Gray, L.G.; Giberson, K.W.; Cheng, C.; Keiffer, R.S.; Dunning, F.B.; Walters, G.K.

    1983-01-01

    A source of spin-polarized electrons based on a laser-pumped flowing helium afterglow is described. He(2 3 S) atoms contained in the afterglow are optically pumped using circularly polarized 1.08-μm (2 3 S→2 3 P) radiation provided by a NaF (F 2+ )( color-center laser. Spin angular momentum conservation in subsequent chemi-ionization reactions with CO 2 produces polarized electrons that are extracted from the afterglow. At low currents, < or approx. =1 μA, polarizations of approx.70%--80% are achieved. At higher currents the polarization decreases, falling to approx.40% at 50 μA. The spin polarization can be simply reversed (P→-P) and the source is suitable for use in the majority of low-energy spin-dependent scattering experiments proposed to date

  20. Electron microscope study of thallium-induced alterations in the oligodendrocytes of the rat area postrema.

    Science.gov (United States)

    Hasan, M; Bajpai, V K; Shipstone, A C

    1977-01-01

    Thallotoxicosis following accidental ingestion of thallium in rodenticides and in cases of homicidal and suicidal ingestion are well documented in the literature. The mechanism of action of thallium, in particular the pathogenesis of its neurotoxic manifestations, is not entirely clear. This is the first electron microscopic investigation dealing with the effect of thallium on the oligodendrocytes of the area postrema. The area postrema is devoid of a blood-brain barrier, indicating that the hemoneural transport of thallous ions may be quite substantial in this region. Rats weighing 155-175 g were given intraperitoneal injections of 5 mg/kg thallous acetate for 7 days (35 mg/kg total dose). Following perfusion-fixation, ultrathin sections of area postrema were examined with an electron microscope. The oligodendrocytes exhibited pleomorphic vacuolated dense bodies in their perikaryon. The findings were also suggestive of the fact that either the multiplication of oligodendrocytes or their aggregation to form "giant cell" was operative.