Electron capture in collisions of Al2+ ions with He atoms at intermediate energies

NASA Astrophysics Data System (ADS)

Watanabe, A.; Sato, H.; Gu, J. P.; Hirsch, G.; Buenker, R. J.; Kimura, M.

2001-09-01

Electron capture resulting from collisions of Al2+ ions with He atoms from 0.15 to 1000 keV/u is investigated using a molecular-orbital representation within a semiclassical frame. Molecular electronic states and corresponding couplings are determined by the ALCHEMY program. Sixteen molecular states all connecting to single-electron-capture processes are included, and hence radial and rotational couplings among these channels are fully considered. The trajectory effect arising from the straight-line, Coulomb, and ground-state potential trajectories for electron-capture and excitation processes is carefully assessed. The electron-capture cross section by ground-state Al2+(2S) ions slowly increases before it reaches a maximum of 1.3×10-16 cm2 at 100 keV/u. Those for metastable Al2+(2P) ions sharply increase with increasing energy, and reach a peak at 1 keV/u with a value of 1.5×10-16 cm2. The earlier experimental data are found to be larger by an order of magnitude although their energy dependence is in good accord with the present result. Excitation cross sections for both the ground and metastable states are found to be much larger by a factor of 2-3 than corresponding capture cross sections above 1 keV/u although they become comparable below this energy.

Electronic case report forms and electronic data capture within clinical trials and pharmacoepidemiology.

PubMed

Rorie, David A; Flynn, Robert W V; Grieve, Kerr; Doney, Alexander; Mackenzie, Isla; MacDonald, Thomas M; Rogers, Amy

2017-09-01

Researchers in clinical and pharmacoepidemiology fields have adopted information technology (IT) and electronic data capture, but these remain underused despite the benefits. This review discusses electronic case report forms and electronic data capture, specifically within pharmacoepidemiology and clinical research. The review used PubMed and the Institute of Electrical and Electronic Engineers library. Search terms used were agreed by the authors and documented. PubMed is medical and health based, whereas Institute of Electrical and Electronic Engineers is technology based. The review focuses on electronic case report forms and electronic data capture, but briefly considers other relevant topics; consent, ethics and security. There were 1126 papers found using the search terms. Manual filtering and reviewing of abstracts further condensed this number to 136 relevant manuscripts. The papers were further categorized: 17 contained study data; 40 observational data; 27 anecdotal data; 47 covering methodology or design of systems; one case study; one literature review; two feasibility studies; and one cost analysis. Electronic case report forms, electronic data capture and IT in general are viewed with enthusiasm and are seen as a cost-effective means of improving research efficiency, educating participants and improving trial recruitment, provided concerns about how data will be protected from misuse can be addressed. Clear operational guidelines and best practises are key for healthcare providers, and researchers adopting IT, and further work is needed on improving integration of new technologies with current systems. A robust method of evaluation for technical innovation is required. © 2017 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.

Electronic case report forms and electronic data capture within clinical trials and pharmacoepidemiology

PubMed Central

Flynn, Robert W. V.; Grieve, Kerr; Doney, Alexander; Mackenzie, Isla; MacDonald, Thomas M.; Rogers, Amy

2017-01-01

Aims Researchers in clinical and pharmacoepidemiology fields have adopted information technology (IT) and electronic data capture, but these remain underused despite the benefits. This review discusses electronic case report forms and electronic data capture, specifically within pharmacoepidemiology and clinical research. Methods The review used PubMed and the Institute of Electrical and Electronic Engineers library. Search terms used were agreed by the authors and documented. PubMed is medical and health based, whereas Institute of Electrical and Electronic Engineers is technology based. The review focuses on electronic case report forms and electronic data capture, but briefly considers other relevant topics; consent, ethics and security. Results There were 1126 papers found using the search terms. Manual filtering and reviewing of abstracts further condensed this number to 136 relevant manuscripts. The papers were further categorized: 17 contained study data; 40 observational data; 27 anecdotal data; 47 covering methodology or design of systems; one case study; one literature review; two feasibility studies; and one cost analysis. Conclusion Electronic case report forms, electronic data capture and IT in general are viewed with enthusiasm and are seen as a cost‐effective means of improving research efficiency, educating participants and improving trial recruitment, provided concerns about how data will be protected from misuse can be addressed. Clear operational guidelines and best practises are key for healthcare providers, and researchers adopting IT, and further work is needed on improving integration of new technologies with current systems. A robust method of evaluation for technical innovation is required. PMID:28276585

Scaling of cross sections for K-electron capture by high-energy protons and alpha-particles from the multielectron atoms

NASA Technical Reports Server (NTRS)

Omidvar, K.

1976-01-01

Electron capture by protons from H, He, and the K-shell of Ar, and alpha particles from He are considered. It is shown that when a certain function of the experimental cross sections is plotted versus the inverse of the collision energy, at high energies the function falls on a straight line. At lower energies the function concaves up or down, depending on the charge of the projectile, the effective charge and the ionization potential of the electron that is being captured. The plot can be used to predict cross sections where experimental data are not available, and as a guide in future experiments. High energy scaling formulas for K-electron capture by low-charge projectiles are given.

21 CFR 172.860 - Fatty acids.

Code of Federal Regulations, 2013 CFR

2013-04-01

... the gas chromatographic-electron capture method prescribed in paragraph (c)(3) of this section. If..._locations.html. (3) The gas chromatographic-electron capture method for testing fatty acids for chick-edema...

21 CFR 172.860 - Fatty acids.

Code of Federal Regulations, 2012 CFR

2012-04-01

... the gas chromatographic-electron capture method prescribed in paragraph (c)(3) of this section. If..._locations.html. (3) The gas chromatographic-electron capture method for testing fatty acids for chick-edema...

Radiative double electron capture in collisions of fully-stripped fluorine ions with thin carbon foils

NASA Astrophysics Data System (ADS)

Elkafrawy, Tamer Mohammad Samy

Radiative double electron capture (RDEC) is a one-step process in ion-atom collisions occurring when two target electrons are captured to a bound state of the projectile simultaneously with the emission of a single photon. The emitted photon has approximately double the energy of the photon emitted due to radiative electron capture (REC), which occurs when a target electron is captured to a projectile bound state with simultaneous emission of a photon. REC and RDEC can be treated as time-reversed photoionization (PI) and double photoionization (DPI), respectively, if loosely-bound target electrons are captured. This concept can be formulated with the principle of detailed balance, in which the processes of our interest can be described in terms of their time-reversed ones. Fully-stripped ions were used as projectiles in the performed RDEC experiments, providing a recipient system free of electron-related Coulomb fields. This allows the target electrons to be transferred without interaction with any of the projectile electrons, enabling accurate investigation of the electron-electron interaction in the vicinity of electromagnetic field. In this dissertation, RDEC was investigated during the collision of fully-stripped fluorine ions with a thin carbon foil and the results are compared with the recent experimental and theoretical studies. In the current work, x rays associated with projectile charge-changing by single and double electron capture and no charge change by F9+ ions were observed and compared with recent work for O8+ ions and with theory. Both the F 9+ and O8+ ions had energies in the ˜MeV/u range. REC, in turn, was investigated as a means to compare with the theoretical predictions of the RDEC/REC cross section ratio. The most significant background processes including various mechanisms of x-ray emission that may interfere with the energy region of interest are addressed in detail. This enables isolation of the contributions of REC and RDEC from the entire continuous spectrum of x-ray emission or at least ensures that the background processes have negligible contribution to the energy range of interest. Special emphasis is given to showing how the data analysis was carried out by the subtraction of the x rays due to contamination lines.

A Benign, Low Z Electron Capture Agent for Negative Ion TPCs

NASA Technical Reports Server (NTRS)

Martoff, C. J.; Dion, M. P.; Hosack, M.; Barton, D.; Black, J. K.

2008-01-01

We have identified nitromethane (CH3NO2) as an effective electron capture agent for negative ion TPCs (NITPCs). We present drift velocity and longitudinal diffusion measurements for negative ion gas mixtures using nitromethane as the capture agent. Not only is nitromethane substantially more benign than the only other identified capture agent, CS2, but its low atomic number will enable the use of the NITPC as a photoelectric X-ray polarimeter in the 1-10 keV band.

2013 R&D 100 Award: Movie-mode electron microscope captures nanoscale

ScienceCinema

Lagrange, Thomas; Reed, Bryan

2018-01-26

A new instrument developed by LLNL scientists and engineers, the Movie Mode Dynamic Transmission Electron Microscope (MM-DTEM), captures billionth-of-a-meter-scale images with frame rates more than 100,000 times faster than those of conventional techniques. The work was done in collaboration with a Pleasanton-based company, Integrated Dynamic Electron Solutions (IDES) Inc. Using this revolutionary imaging technique, a range of fundamental and technologically important material and biological processes can be captured in action, in complete billionth-of-a-meter detail, for the first time. The primary application of MM-DTEM is the direct observation of fast processes, including microstructural changes, phase transformations and chemical reactions, that shape real-world performance of nanostructured materials and potentially biological entities. The instrument could prove especially valuable in the direct observation of macromolecular interactions, such as protein-protein binding and host-pathogen interactions. While an earlier version of the technology, Single Shot-DTEM, could capture a single snapshot of a rapid process, MM-DTEM captures a multiframe movie that reveals complex sequences of events in detail. It is the only existing technology that can capture multiple electron microscopy images in the span of a single microsecond.

2013 R&D 100 Award: Movie-mode electron microscope captures nanoscale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lagrange, Thomas; Reed, Bryan

2014-04-03

A new instrument developed by LLNL scientists and engineers, the Movie Mode Dynamic Transmission Electron Microscope (MM-DTEM), captures billionth-of-a-meter-scale images with frame rates more than 100,000 times faster than those of conventional techniques. The work was done in collaboration with a Pleasanton-based company, Integrated Dynamic Electron Solutions (IDES) Inc. Using this revolutionary imaging technique, a range of fundamental and technologically important material and biological processes can be captured in action, in complete billionth-of-a-meter detail, for the first time. The primary application of MM-DTEM is the direct observation of fast processes, including microstructural changes, phase transformations and chemical reactions, that shapemore » real-world performance of nanostructured materials and potentially biological entities. The instrument could prove especially valuable in the direct observation of macromolecular interactions, such as protein-protein binding and host-pathogen interactions. While an earlier version of the technology, Single Shot-DTEM, could capture a single snapshot of a rapid process, MM-DTEM captures a multiframe movie that reveals complex sequences of events in detail. It is the only existing technology that can capture multiple electron microscopy images in the span of a single microsecond.« less

Quasiclassical treatment of the Auger effect in slow ion-atom collisions

NASA Astrophysics Data System (ADS)

Frémont, F.

2017-09-01

A quasiclassical model based on the resolution of Hamilton equations of motion is used to get evidence for Auger electron emission following double-electron capture in 150-keV N e10 ++He collisions. Electron-electron interaction is taken into account during the collision by using pure Coulombic potential. To make sure that the helium target is stable before the collision, phenomenological potentials for the electron-nucleus interactions that simulate the Heisenberg principle are included in addition to the Coulombic potential. First, single- and double-electron captures are determined and compared with previous experiments and theories. Then, integration time evolution is calculated for autoionizing and nonautoionizing double capture. In contrast with single capture, the number of electrons originating from autoionization slowly increases with integration time. A fit of the calculated cross sections by means of an exponential function indicates that the average lifetime is 4.4 ×10-3a .u . , in very good agreement with the average lifetime deduced from experiments and a classical model introduced to calculate individual angular momentum distributions. The present calculation demonstrates the ability of classical models to treat the Auger effect, which is a pure quantum effect.

Study of photon emission by electron capture during solar nuclei acceleration. 2: Delimitation of conditions for charge transfert establishment

NASA Technical Reports Server (NTRS)

Perez-Peraza, J.; Alvarez, M.; Gallegos, A.

1985-01-01

The conditions for establishment of charge transfer during acceleration of nuclei up to Fe, for typical conditions of solar flare regions T = 5 x 10 to the 3rd power to 2.5 x 10 to the 8th power degrees K were explored. Results show that such conditions are widely assorted, depending on the acceleration mechanism, the kind of projections and their velocity, the target elements, the source temperature and consequently on the degree of ionization of matter and the local charge state of the accelerated ions. Nevertheless, in spite of that assorted behavior, there are some general tendencies that can be summarized as follows. In atomic H electron capture is systematically established from thermal energies up to high energies, whatever the element and for both acceleration process. For a given element and fixed temperature (T), the probability and energy domain of electron capture and loss with Fermi are higher than with Betatron acceleration. For a given acceleration process the heavier the ion the higher the probability and the wider the energy range for electron capture and loss. For given acceleration mechanism and fixed element the importance and energy domain of capture and loss increase with T: for those reasons, the energy range of charge equilibrium (illustrated with solid lines on the next figs.) is wider with Fermi and increases with temperature and atomic number of projectiles. For the same reasons, electron loss is smaller while the lighter the element, the lower the temperature and the Betatron process, such that there are conditions for which electron loss is not allowed at low energies, but only electron capture is established.

Development of an Electron-capture Technique Specific for Explosives Detection

DOT National Transportation Integrated Search

1974-07-01

This document contains information on the design, fabrication, and testing of a prototype detector specific for explosives which employs electron-capture sensors. The technique used exploits the observation that the electronegative vapors from explos...

Search for neutrinoless double-electron capture of 156Dy

NASA Astrophysics Data System (ADS)

Finch, S. W.; Tornow, W.

2015-12-01

Background: Multiple large collaborations are currently searching for neutrinoless double-β decay, with the ultimate goal of differentiating the Majorana-Dirac nature of the neutrino. Purpose: Investigate the feasibility of resonant neutrinoless double-electron capture, an experimental alternative to neutrinoless double-β decay. Method: Two clover germanium detectors were operated underground in coincidence to search for the de-excitation γ rays of 156Gd following the neutrinoless double-electron capture of 156Dy. 231.95 d of data were collected at the Kimballton underground research facility with a 231.57 mg enriched 156Dy sample. Results: No counts were seen above background and half-life limits are set at O (1016-1018) yr for the various decay modes of 156Dy. Conclusion: Low background spectra were efficiently collected in the search for neutrinoless double-electron capture of 156Dy, although the low natural abundance and associated lack of large quantities of enriched samples hinders the experimental reach.

Measuring double-electron capture with liquid xenon experiments

NASA Astrophysics Data System (ADS)

Mei, D.-M.; Marshall, I.; Wei, W.-Z.; Zhang, C.

2014-01-01

We investigate the possibilities of observing the decay mode for 124Xe in which two electrons are captured, two neutrinos are emitted, and the final daughter nucleus is in its ground state, using dark matter experiments with liquid xenon. The first upper limit of the decay half-life is calculated to be 1.66 × 1021 years at a 90% confidence level (C.L.) obtained with the published background data from the XENON100 experiment. Employing a known background model from the large underground xenon (LUX) experiment, we predict that the detection of double-electron capture of 124Xe to the ground state of 124Te with LUX will have approximately 115 events, assuming a half-life of 2.9 × 1021 years. We conclude that measuring 124Xe 2ν double-electron capture to the ground state of 124Te can be performed more precisely with the proposed LUX-Zeplin (LZ) experiment.

Search for two-neutrino double electron capture of 124Xe with XENON100

NASA Astrophysics Data System (ADS)

Aprile, E.; Aalbers, J.; Agostini, F.; Alfonsi, M.; Amaro, F. D.; Anthony, M.; Arneodo, F.; Barrow, P.; Baudis, L.; Bauermeister, B.; Benabderrahmane, M. L.; Berger, T.; Breur, P. A.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Bütikofer, L.; Calvén, J.; Cardoso, J. M. R.; Cervantes, M.; Cichon, D.; Coderre, D.; Colijn, A. P.; Conrad, J.; Cussonneau, J. P.; Decowski, M. P.; de Perio, P.; di Gangi, P.; di Giovanni, A.; Diglio, S.; Duchovni, E.; Fei, J.; Ferella, A. D.; Fieguth, A.; Franco, D.; Fulgione, W.; Gallo Rosso, A.; Galloway, M.; Gao, F.; Garbini, M.; Geis, C.; Goetzke, L. W.; Greene, Z.; Grignon, C.; Hasterok, C.; Hogenbirk, E.; Itay, R.; Kaminsky, B.; Kessler, G.; Kish, A.; Landsman, H.; Lang, R. F.; Lellouch, D.; Levinson, L.; Le Calloch, M.; Levy, C.; Lin, Q.; Lindemann, S.; Lindner, M.; Lopes, J. A. M.; Manfredini, A.; Marrodán Undagoitia, T.; Masbou, J.; Massoli, F. V.; Masson, D.; Mayani, D.; Meng, Y.; Messina, M.; Micheneau, K.; Miguez, B.; Molinario, A.; Murra, M.; Naganoma, J.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pakarha, P.; Pelssers, B.; Persiani, R.; Piastra, F.; Pienaar, J.; Piro, M.-C.; Plante, G.; Priel, N.; Rauch, L.; Reichard, S.; Reuter, C.; Rizzo, A.; Rosendahl, S.; Rupp, N.; Dos Santos, J. M. F.; Sartorelli, G.; Scheibelhut, M.; Schindler, S.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Shagin, P.; Silva, M.; Simgen, H.; Sivers, M. V.; Stein, A.; Thers, D.; Tiseni, A.; Trinchero, G.; Tunnell, C. D.; Wall, R.; Wang, H.; Weber, M.; Wei, Y.; Weinheimer, C.; Wulf, J.; Zhang, Y.; Xenon Collaboration

2017-02-01

Two-neutrino double electron capture is a rare nuclear decay where two electrons are simultaneously captured from the atomic shell. For 124Xe this process has not yet been observed and its detection would provide a new reference for nuclear matrix element calculations. We have conducted a search for two-neutrino double electron capture from the K shell of 124Xe using 7636 kg d of data from the XENON100 dark matter detector. Using a Bayesian analysis we observed no significant excess above background, leading to a lower 90% credibility limit on the half-life T1 /2>6.5 ×1020 yr. We have also evaluated the sensitivity of the XENON1T experiment, which is currently being commissioned, and found a sensitivity of T1 /2>6.1 ×1022 yr after an exposure of 2 t yr .

Effect of collective response on electron capture and excitation in collisions of highly charged ions with fullerenes.

PubMed

Kadhane, U; Misra, D; Singh, Y P; Tribedi, Lokesh C

2003-03-07

Projectile deexcitation Lyman x-ray emission following electron capture and K excitation has been studied in collisions of bare and Li-like sulphur ions (of energy 110 MeV) with fullerenes (C(60)/C(70)) and different gaseous targets. The intensity ratios of different Lyman x-ray lines in collisions with fullerenes are found to be substantially lower than those for the gas targets, both for capture and excitation. This has been explained in terms of a model based on "solidlike" effect, namely, wakefield induced stark mixing of the excited states populated via electron capture or K excitation: a collective phenomenon of plasmon excitation in the fullerenes under the influence of heavy, highly charged ions.

Scanning electron microscopy of Ancylostoma spp. dog infective larvae captured and destroyed by the nematophagous fungus Duddingtonia flagrans.

PubMed

Maciel, A S; Araújo, J V; Campos, A K; Benjamin, L A; Freitas, L G

2009-06-01

The interaction between the nematode-trapping fungus Duddingtonia flagrans (isolate CG768) against Ancylostoma spp. dog infective larvae (L(3)) was evaluated by means of scanning electron microscopy. Adhesive network trap formation was observed 6h after the beginning of the interaction, and the capture of Ancylostoma spp. L(3) was observed 8h after the inoculation these larvae on the cellulose membranes colonized by the fungus. Scanning electron micrographs were taken at 0, 12, 24, 36 and 48 h, where 0 is the time when Ancylostoma spp. L(3) was first captured by the fungus. Details of the capture structure formed by the fungus were described. Nematophagous Fungus Helper Bacteria (NHB) were found at interactions points between the D. flagrans and Ancylostoma spp. L(3). The cuticle penetration by the differentiated fungal hyphae with the exit of nematode internal contents was observed 36 h after the capture. Ancylostoma spp. L(3) were completely destroyed after 48 h of interaction with the fungus. The scanning electron microscopy technique was efficient on the study of this interaction, showing that the nematode-trapping fungus D. flagrans (isolate CG768) is a potential exterminator of Ancylostoma spp. L(3).

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of chlorinated pesticides in aquatic tissue by capillary-column gas chromatography with electron-capture detection

USGS Publications Warehouse

Leiker, Thomas J.; Madsen, J.E.; Deacon, J.R.; Foreman, W.T.

1995-01-01

A method for the determination of chlorinated organic compounds in aquatic tissue by dual capillary-column gas chromatography with electron-capture detection is described. Whole-body-fish or corbicula tissue is homogenized, Soxhlet extracted, lipid removed by gel permeation chromatography, and fractionated using alumina/silica adsorption chromatography. The extracts are analyzed by dissimilar capillary-column gas chromatography with electron-capture detection. The method reporting limits are 5 micrograms per kilogram (μg/kg) for chlorinated compounds, 50 μg/kg for polychlorinated biphenyls, and 200 μg/kg for toxaphene.

Alkali metal mediated C-C bond coupling reaction

NASA Astrophysics Data System (ADS)

Tachikawa, Hiroto

2015-02-01

Metal catalyzed carbon-carbon (C-C) bond formation is one of the important reactions in pharmacy and in organic chemistry. In the present study, the electron and hole capture dynamics of a lithium-benzene sandwich complex, expressed by Li(Bz)2, have been investigated by means of direct ab-initio molecular dynamics method. Following the electron capture of Li(Bz)2, the structure of [Li(Bz)2]- was drastically changed: Bz-Bz parallel form was rapidly fluctuated as a function of time, and a new C-C single bond was formed in the C1-C1' position of Bz-Bz interaction system. In the hole capture, the intermolecular vibration between Bz-Bz rings was only enhanced. The mechanism of C-C bond formation in the electron capture was discussed on the basis of theoretical results.

Resonant electron capture by aspartame and aspartic acid molecules.

PubMed

Muftakhov, M V; Shchukin, P V

2016-12-30

The processes for dissociative electron capture are the key mechanisms for decomposition of biomolecules, proteins in particular, under interaction with low-energy electrons. Molecules of aspartic acid and aspartame, i.e. modified dipeptides, were studied herein to define the impact of the side functional groups on peptide chain decomposition in resonant electron-molecular reactions. The processes of formation and decomposition of negative ions of both aspartame and aspartic acid were studied by mass spectrometry of negative ions under resonant electron capture. The obtained mass spectra were interpreted under thermochemical analysis by quantum chemical calculations. Main channels of negative molecular ions fragmentation were found and characteristic fragment ions were identified. The СООН fragment of the side chain in aspartic acid is shown to play a key role like the carboxyl group in amino acids and aliphatic oligopeptides. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Electron capture strength for Ni60,62 and Ni58,60,62,64(p, n)Cu58,60,62,64 reactions at 134.3 MeV

NASA Astrophysics Data System (ADS)

Anantaraman, N.; Austin, Sam M.; Brown, B. A.; Crawley, G. M.; Galonsky, A.; Zegers, R. G. T.; Anderson, B. D.; Baldwin, A. R.; Flanders, B. S.; Madey, R.; Watson, J. W.; Foster, C. C.

2008-12-01

Background: The strength of electron capture for medium mass nuclei has a significant effect on the evolution of supernovae. There is insufficient knowledge of these strengths and very little data for important radioactive nuclei. Purpose: Determine whether it is feasible to obtain EC strength from studies of To+1 excitations in (p, n) reactions, and whether this might yield information for radioactive nuclei. Methods: Cross sections for the Ni58,60,62,64(p, n)Cu58,60,62,64 reactions were measured over the angular range of 0.3∘ to 11.6∘ at 134.3 MeV using the IUCF neutron time-of-flight facility. Results: The To+1 excitations in Ni60,62 were identified by comparison with inelastic proton scattering spectra, their B(GT) were extracted, and the corresponding electron capture rates in supernovae were calculated. Data from the TRIUMF (n, p) experiments at 198 MeV were reanalyzed; the electron capture rates for the reanalyzed data are in moderately good agreement with the higher resolution (p, n) results, but differ in detail. The possibility of future measurements with radioactive nuclei was considered. Conclusions: It may be possible to obtain low-lying electron capture strength for radioactive nuclei by studying (p, n) reactions in inverse kinematics.

Nuclear structure and weak rates of heavy waiting point nuclei under rp-process conditions

NASA Astrophysics Data System (ADS)

Nabi, Jameel-Un; Böyükata, Mahmut

2017-01-01

The structure and the weak interaction mediated rates of the heavy waiting point (WP) nuclei 80Zr, 84Mo, 88Ru, 92Pd and 96Cd along N = Z line were studied within the interacting boson model-1 (IBM-1) and the proton-neutron quasi-particle random phase approximation (pn-QRPA). The energy levels of the N = Z WP nuclei were calculated by fitting the essential parameters of IBM-1 Hamiltonian and their geometric shapes were predicted by plotting potential energy surfaces (PESs). Half-lives, continuum electron capture rates, positron decay rates, electron capture cross sections of WP nuclei, energy rates of β-delayed protons and their emission probabilities were later calculated using the pn-QRPA. The calculated Gamow-Teller strength distributions were compared with previous calculation. We present positron decay and continuum electron capture rates on these WP nuclei under rp-process conditions using the same model. For the rp-process conditions, the calculated total weak rates are twice the Skyrme HF+BCS+QRPA rates for 80Zr. For remaining nuclei the two calculations compare well. The electron capture rates are significant and compete well with the corresponding positron decay rates under rp-process conditions. The finding of the present study supports that electron capture rates form an integral part of the weak rates under rp-process conditions and has an important role for the nuclear model calculations.

Extraction of highly charged ions from the Berlin Electron Beam Ion Trap for interactions with a gas target

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allen, F.I.; Biedermann, C.; Radtke, R.

2006-03-15

Highly charged ions are extracted from the Berlin Electron Beam Ion Trap for investigations of charge exchange with a gas target. The classical over-the-barrier model for slow highly charged ions describes this process, whereby one or more electrons are captured from the target into Rydberg states of the ion. The excited state relaxes via a radiative cascade of the electron to ground energy. The cascade spectra are characteristic of the capture state. We investigate x-ray photons emitted as a result of interactions between Ar{sup 17+} ions at energies {<=}5q keV with Ar atoms. Of particular interest is the velocity dependencemore » of the angular momentum capture state l{sub c}.« less

Conductive Graphitic Carbon Nitride as an Ideal Material for Electrocatalytically Switchable CO2 Capture

PubMed Central

Tan, Xin; Kou, Liangzhi; Tahini, Hassan A.; Smith, Sean C.

2015-01-01

Good electrical conductivity and high electron mobility of the sorbent materials are prerequisite for electrocatalytically switchable CO2 capture. However, no conductive and easily synthetic sorbent materials are available until now. Here, we examined the possibility of conductive graphitic carbon nitride (g-C4N3) nanosheets as sorbent materials for electrocatalytically switchable CO2 capture. Using first-principle calculations, we found that the adsorption energy of CO2 molecules on g-C4N3 nanosheets can be dramatically enhanced by injecting extra electrons into the adsorbent. At saturation CO2 capture coverage, the negatively charged g-C4N3 nanosheets achieve CO2 capture capacities up to 73.9 × 1013 cm−2 or 42.3 wt%. In contrast to other CO2 capture approaches, the process of CO2 capture/release occurs spontaneously without any energy barriers once extra electrons are introduced or removed, and these processes can be simply controlled and reversed by switching on/off the charging voltage. In addition, these negatively charged g-C4N3 nanosheets are highly selective for separating CO2 from mixtures with CH4, H2 and/or N2. These predictions may prove to be instrumental in searching for a new class of experimentally feasible high-capacity CO2 capture materials with ideal thermodynamics and reversibility. PMID:26621618

ELECTRON-CAPTURE AND β-DECAY RATES FOR sd-SHELL NUCLEI IN STELLAR ENVIRONMENTS RELEVANT TO HIGH-DENSITY O–NE–MG CORES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suzuki, Toshio; Toki, Hiroshi; Nomoto, Ken’ichi, E-mail: suzuki@phys.chs.nihon-u.ac.jp

Electron-capture and β-decay rates for nuclear pairs in the sd-shell are evaluated at high densities and high temperatures relevant to the final evolution of electron-degenerate O–Ne–Mg cores of stars with initial masses of 8–10 M{sub ⊙}. Electron capture induces a rapid contraction of the electron-degenerate O–Ne–Mg core. The outcome of rapid contraction depends on the evolutionary changes in the central density and temperature, which are determined by the competing processes of contraction, cooling, and heating. The fate of the stars is determined by these competitions, whether they end up with electron-capture supernovae or Fe core-collapse supernovae. Since the competing processes aremore » induced by electron capture and β-decay, the accurate weak rates are crucially important. The rates are obtained for pairs with A = 20, 23, 24, 25, and 27 by shell-model calculations in the sd-shell with the USDB Hamiltonian. Effects of Coulomb corrections on the rates are evaluated. The rates for pairs with A = 23 and 25 are important for nuclear Urca processes that determine the cooling rate of the O–Ne–Mg core, while those for pairs with A = 20 and 24 are important for the core contraction and heat generation rates in the core. We provide these nuclear rates at stellar environments in tables with fine enough meshes at various densities and temperatures for studies of astrophysical processes sensitive to the rates. In particular, the accurate rate tables are crucially important for the final fates of not only O–Ne–Mg cores but also a wider range of stars, such as C–O cores of lower-mass stars.« less

Alkali metal mediated C–C bond coupling reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tachikawa, Hiroto, E-mail: hiroto@eng.hokudai.ac.jp

2015-02-14

Metal catalyzed carbon-carbon (C–C) bond formation is one of the important reactions in pharmacy and in organic chemistry. In the present study, the electron and hole capture dynamics of a lithium-benzene sandwich complex, expressed by Li(Bz){sub 2}, have been investigated by means of direct ab-initio molecular dynamics method. Following the electron capture of Li(Bz){sub 2}, the structure of [Li(Bz){sub 2}]{sup −} was drastically changed: Bz–Bz parallel form was rapidly fluctuated as a function of time, and a new C–C single bond was formed in the C{sub 1}–C{sub 1}′ position of Bz–Bz interaction system. In the hole capture, the intermolecular vibrationmore » between Bz–Bz rings was only enhanced. The mechanism of C–C bond formation in the electron capture was discussed on the basis of theoretical results.« less

Electron removal from H and He atoms in collisions with C q+ , O q+ ions

NASA Astrophysics Data System (ADS)

Janev, R. K.; McDowell, M. R. C.

1984-06-01

Cross sections for electron capture and ionisation in collision of partially and completely stripped C q+ , N q+ and O q+ ions with hydrogen and helium atoms have been calculated at selected energies. The classical trajectory Monte Carlo method was used with a variable-charge pseudopotential to describe the interaction of the active electron with the projectile ion. A scalling relationship has been derived for the electron removal (capture and ionisation) cross section which allows a unifield representation of the data.

Electron capture in collisions of Si3+ ions with atomic hydrogen from low to intermediate energies

NASA Astrophysics Data System (ADS)

Liu, C. H.; Liu, L.; Wang, J. G.

2014-07-01

The electron capture process for the Si3+(3s) + H(1s) collisions is investigated by the quantum-mechanical molecular orbital close-coupling (MOCC) method and by the two-center atomic orbital close-coupling (AOCC) method in the energy range of 10-5-10 keV/u and 0.8-200 keV/u, respectively. Total and state-selective cross sections are presented and compared with the available theoretical and experimental results. The present MOCC and AOCC results agree well with the experimental measurements, but show some discrepancy with the calculations of Wang et al. [Phys. Rev. A 74, 052709 (2006), 10.1103/PhysRevA.74.052709] at E > 40 eV/u because of the inclusion of rotational couplings, which play important roles in the electron capture process. At lower energies, the present results are about three to five times smaller than those of Wang et al. due to the difference in the molecular data at large internuclear distances. The energy behaviors of the electron capture cross sections are discussed on the basis of identified reaction mechanisms.

Atypical behavior in the electron capture induced dissociation of biologically relevant transition metal ion complexes of the peptide hormone oxytocin

NASA Astrophysics Data System (ADS)

Kleinnijenhuis, Anne J.; Mihalca, Romulus; Heeren, Ron M. A.; Heck, Albert J. R.

2006-07-01

Doubly protonated ions of the disulfide bond containing nonapeptide hormone oxytocin and oxytocin complexes with different transition metal ions, that have biological relevance under physiological conditions, were subjected to electron capture dissociation (ECD) to probe their structural features in the gas phase. Although, all the ECD spectra were strikingly different, typical ECD behavior was observed for complexes of the nonapeptide hormone oxytocin with Ni2+, Co2+ and Zn2+, i.e., abundant c/z' and a'/y backbone cleavages and ECD characteristic S-S and S-C bond cleavages were observed. We propose that, although in the oxytocin-transition metal ion complexes the metal ions serve as the main initial capture site, the captured electron is transferred to other sites in the complex to form a hydrogen radical, which drives the subsequent typical ECD fragmentations. The complex of oxytocin with Cu2+ displayed noticeably different ECD behavior. The fragment ions were similar to fragment ions typically observed with low-energy collision induced dissociation (CID). We propose that the electrons captured by the oxytocin-Cu2+ complex might be favorably involved in reducing the Cu2+ metal ion to Cu+. Subsequent energy redistribution would explain the observed low-energy CID-type fragmentations. Electron capture resulted also in quite different specific cleavage sites for the complexes of oxytocin with Ni2+, Co2+ and Zn2+. This is an indication for structural differences in these complexes possibly linked to their significantly different biological effects on oxytocin-receptor binding, and suggests that ECD may be used to study subtle structural differences in transition metal ion-peptide complexes.

Capture and Emission of Charge Carriers by Quantum Well

NASA Astrophysics Data System (ADS)

Davydov, V. N.; Karankevich, O. A.

2018-06-01

The interaction of electrons from the conduction band of the barrier layer of a LED heterostructure with the quantum well size-quantization level described by the capture time and emission time of charge carriers is considered. Relaxation of an excess energy upon capture and emission of charge carriers occurs as a result of their collisions with phonons of the quantum well substance and the "barrier layer-quantum well" interface. Analytical expressions are obtained for the interaction times, taking into account the depth of the sizequantization level, involved in the interaction with electrons, and the width of the well. Numerical estimates show that in real conditions, the capture time is shorter than the emission time, and this difference increases with increasing depth of the level. At shallow depths, the capture and emission times are comparable.

Comparative study of the double-K -shell-vacancy production in single- and double-electron-capture decay

NASA Astrophysics Data System (ADS)

Ratkevich, S. S.; Gangapshev, A. M.; Gavrilyuk, Yu. M.; Karpeshin, F. F.; Kazalov, V. V.; Kuzminov, V. V.; Panasenko, S. I.; Trzhaskovskaya, M. B.; Yakimenko, S. P.

2017-12-01

Background: A double-K -electron capture is a rare nuclear-atomic process in which two K electrons are captured simultaneously from the atomic shell. A "hollow atom" is created as a result of this process. In single-K -shell electron-capture decays, there is a small probability that the second electron in the K shell is excited to an unoccupied level or can (mostly) be ejected to the continuum. In either case, a double vacancy is created in the K shell. The relaxation of the double-K -shell vacancy, accompanied by the emission of two K -fluorescence photons, makes it possible to perform experimental studies of such rare processes with the large-volume proportional gas chamber. Purpose: The purpose of the present analysis is to estimate a double-K -shell vacancy creation probability per K -shell electron capture PK K of 81Kr, as well as to measure the half-life of 78Kr relative to 2 ν 2 K capture. Method: Time-resolving current pulse from the large low-background proportional counter (LPC), filled with the krypton sample, was applied to detect triple coincidences of "shaked" electrons and two fluorescence photons. Results: The number of K -shell vacancies per the K -electron capture, produced as a result of the shake-off process, has been measured for the decay of 81Kr. The probability for this decay was found to be PK K=(5.7 ±0.8 ) ×10-5 with a systematic error of (ΔPKK) syst=±0.4 ×10-5 . For the 78Kr(2 ν 2 K ) decay, the comparative study of single- and double-capture decays allowed us to obtain the signal-to-background ratio up to 15/1. The half-life T1/2 2 ν 2 K(g .s .→g .s .) =[1 .9-0.7+1.3(stat) ±0.3 (syst) ] ×1022 y is determined from the analysis of data that have been accumulated over 782 days of live measurements in the experiment that used samples consisted of 170.6 g of 78Kr. Conclusions: The data collected during low background measurements using the LPC were analyzed to search the rare atomic and nuclear processes. We have determined PKK exp for the E C decay of 81Kr, which are in satisfactory agreement with Z-2 dependence of PK K predicted by Primakoff and Porter. This made possible to more accurately determine the background contribution in the energy region of our interest for the search for the 2 K capture in 78Kr. The general procedure of data analysis allowed us to determine the half-life of 78Kr relative to 2 ν 2 K transition with a greater statistical accuracy than in our previous works.

Destruction of Peptides and Nucleosides in Reactions with Low-Energy Electrons

NASA Astrophysics Data System (ADS)

Muftakhov, M. V.; Shchukin, P. V.

2018-05-01

Mass-spectrometry of negative ions is used to study dissociative electron capture by molecules of several nucleosides, simplest di- and tripeptides, and modified dipeptides. Energy domains and efficiencies of dissociative capture are determined for the objects under study, and threshold energies of several fragmentation processes are estimated. It is shown that cytidine and peptides are stable against fragmentation due to simple bond breaking at electron energies ranging from 0 to 1 eV.

New developments in electron microscopy for serial image acquisition of neuronal profiles.

PubMed

Kubota, Yoshiyuki

2015-02-01

Recent developments in electron microscopy largely automate the continuous acquisition of serial electron micrographs (EMGs), previously achieved by laborious manual serial ultrathin sectioning using an ultramicrotome and ultrastructural image capture process with transmission electron microscopy. The new systems cut thin sections and capture serial EMGs automatically, allowing for acquisition of large data sets in a reasonably short time. The new methods are focused ion beam/scanning electron microscopy, ultramicrotome/serial block-face scanning electron microscopy, automated tape-collection ultramicrotome/scanning electron microscopy and transmission electron microscope camera array. In this review, their positive and negative aspects are discussed. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

General features of the dissociative recombination of polyatomic molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pratt, S. T.; Jungen, Ch.; Schneider, I. F.

We discuss some aspects of a simple expression for the low-energy dissociative recombination cross section that applies when the recombination process is dominated by the indirect mechanism. In most previous applications, this expression has been applied to capture into vibrationally excited Rydberg states with the assumption that capture is always followed by prompt dissociation. Here we consider the dissociative recombination of larger polyatomic ions and electrons. More specifically, we consider capture into electronically core-excited Rydberg states, and begin to assess its potential importance for larger systems.

General features of the dissociative recombination of polyatomic molecules

DOE PAGES

Pratt, S. T.; Jungen, Ch.; Schneider, I. F.; ...

2015-01-29

We discuss some aspects of a simple expression for the low-energy dissociative recombination cross section that applies when the recombination process is dominated by the indirect mechanism. In most previous applications, this expression has been applied to capture into vibrationally excited Rydberg states with the assumption that capture is always followed by prompt dissociation. Here we consider the dissociative recombination of larger polyatomic ions and electrons. More specifically, we consider capture into electronically core-excited Rydberg states, and begin to assess its potential importance for larger systems.

Differential Mobility Spectrometry: Preliminary Findings on Determination of Fundamental Constants

NASA Technical Reports Server (NTRS)

Limero, Thomas; Cheng, Patti; Boyd, John

2007-01-01

The electron capture detector (ECD) has been used for 40+ years (1) to derive fundamental constants such as a compound's electron affinity. Given this historical perspective, it is not surprising that differential mobility spectrometry (DMS) might be used in a like manner. This paper will present data from a gas chromatography (GC)-DMS instrument that illustrates the potential capability of this device to derive fundamental constants for electron-capturing compounds. Potential energy curves will be used to provide possible explanation of the data.

Electron capture and excitation processes in H+-H collisions in dense quantum plasmas

NASA Astrophysics Data System (ADS)

Jakimovski, D.; Markovska, N.; Janev, R. K.

2016-10-01

Electron capture and excitation processes in proton-hydrogen atom collisions taking place in dense quantum plasmas are studied by employing the two-centre atomic orbital close-coupling (TC-AOCC) method. The Debye-Hückel cosine (DHC) potential is used to describe the plasma screening effects on the Coulomb interaction between charged particles. The properties of a hydrogen atom with DHC potential are investigated as a function of the screening strength of the potential. It is found that the decrease in binding energy of nl levels with increasing screening strength is considerably faster than in the case of the Debye-Hückel (DH) screening potential, appropriate for description of charged particle interactions in weakly coupled classical plasmas. This results in a reduction in the number of bound states in the DHC potential with respect to that in the DH potential for the same plasma screening strength, and is reflected in the dynamics of excitation and electron capture processes for the two screened potentials. The TC-AOCC cross sections for total and state-selective electron capture and excitation cross sections with the DHC potential are calculated for a number of representative screening strengths in the 1-300 keV energy range and compared with those for the DH and pure Coulomb potential. The total capture cross sections for a selected number of screening strengths are compared with the available results from classical trajectory Monte Carlo calculations.

Examining Authenticity: An Initial Exploration of the Suitability of Handwritten Electronic Signatures.

PubMed

Heckeroth, J; Boywitt, C D

2017-06-01

Considering the increasing relevance of handwritten electronically captured signatures, we evaluated the ability of forensic handwriting examiners (FHEs) to distinguish between authentic and simulated electronic signatures. Sixty-six professional FHEs examined the authenticity of electronic signatures captured with software by signotec on a smartphone Galaxy Note 4 by Samsung and signatures made with a ballpoint pen on paper (conventional signatures). In addition, we experimentally varied the name ("J. König" vs. "A. Zaiser") and the status (authentic vs. simulated) of the signatures in question. FHEs' conclusions about the authenticity did not show a statistically significant general difference between electronic and conventional signatures. Furthermore, no significant discrepancies between electronic and conventional signatures were found with regard to other important aspects of the authenticity examination such as questioned signatures' graphic information content, the suitability of the provided sample signatures, the necessity of further examinations and the levels of difficulty of the cases under examination. Thus, this study did not reveal any indications that electronic signatures captured with software by signotec on a Galaxy Note 4 are less well suited than conventional signatures for the examination of authenticity, precluding potential technical problems concerning the integrity of electronic signatures. Copyright © 2017 Elsevier B.V. All rights reserved.

Electron emission from transfer ionization reaction in 30 keV amu‑1 He 2+ on Ar collision

NASA Astrophysics Data System (ADS)

Amaya-Tapia, A.; Antillón, A.; Estrada, C. D.

2018-06-01

A model is presented that describes the transfer ionization process in H{e}2++Ar collision at a projectile energy of 30 keV amu‑1. It is based on a semiclassical independent-particle close-coupling method that yields a reasonable agreement between calculated and experimental values of the total single-ionization and single-capture cross sections. It is found that the transfer ionization reaction is predominantly carried out through simultaneous capture and ionization, rather than by sequential processes. The transfer-ionization differential cross section in energy that is obtained satisfactorily reproduces the global behavior of the experimental data. Additionally, the probabilities of capture and ionization as function of the impact parameter for H{e}2++A{r}+ and H{e}++A{r}+ collisions are calculated, as far as we know, for the first time. The results suggest that the model captures essential elements that describe the two-electron transfer ionization process and could be applied to systems and processes of two electrons.

EVALUATION OF N-METHYL-N-TERT-BUTYLDIMETHYLSILYLTRIFLUOROACETAMIDE FOR ENVIRONMENTAL ANALYSIS UNDER BOTH EIMS AND ELECTRON CAPTURE NICIMS CONDITIONS AND COMPARISON TO TRIMETHYLSILYL REAGENTS UNDER EIMS

EPA Science Inventory

Sewage effluent was analyzed for 3,5,6-trichloropyridinol (TCP) by extracting one liter of water using liquid-liquid extraction and determined by GC/MS operated in the negative ion chemical ionization (electron capture) mode, TCP is the major metabolite of the commonly used insec...

Hubble Space Telescope photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-04

S61-E-008 (4 Dec 1993) --- This view of the Earth-orbiting Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. This view was taken during rendezvous operations. Endeavour's crew captured the HST on December 4, 1993 in order to service the telescope. Over a period of five days, four of the crew members will work in alternating pairs outside Endeavour's shirt sleeve environment. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Electronic Still Camera image of Astronaut Claude Nicollier working with RMS

NASA Image and Video Library

1993-12-05

S61-E-006 (5 Dec 1993) --- The robot arm controlling work of Swiss scientist Claude Nicollier was photographed with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. With the mission specialist's assistance, Endeavour's crew captured the Hubble Space Telescope (HST) on December 4, 1993. Four of the seven crew members will work in alternating pairs outside Endeavour's shirt sleeve environment to service the giant telescope. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Collecting verbal autopsies: improving and streamlining data collection processes using electronic tablets.

PubMed

Flaxman, Abraham D; Stewart, Andrea; Joseph, Jonathan C; Alam, Nurul; Alam, Sayed Saidul; Chowdhury, Hafizur; Mooney, Meghan D; Rampatige, Rasika; Remolador, Hazel; Sanvictores, Diozele; Serina, Peter T; Streatfield, Peter Kim; Tallo, Veronica; Murray, Christopher J L; Hernandez, Bernardo; Lopez, Alan D; Riley, Ian Douglas

2018-02-01

There is increasing interest in using verbal autopsy to produce nationally representative population-level estimates of causes of death. However, the burden of processing a large quantity of surveys collected with paper and pencil has been a barrier to scaling up verbal autopsy surveillance. Direct electronic data capture has been used in other large-scale surveys and can be used in verbal autopsy as well, to reduce time and cost of going from collected data to actionable information. We collected verbal autopsy interviews using paper and pencil and using electronic tablets at two sites, and measured the cost and time required to process the surveys for analysis. From these cost and time data, we extrapolated costs associated with conducting large-scale surveillance with verbal autopsy. We found that the median time between data collection and data entry for surveys collected on paper and pencil was approximately 3 months. For surveys collected on electronic tablets, this was less than 2 days. For small-scale surveys, we found that the upfront costs of purchasing electronic tablets was the primary cost and resulted in a higher total cost. For large-scale surveys, the costs associated with data entry exceeded the cost of the tablets, so electronic data capture provides both a quicker and cheaper method of data collection. As countries increase verbal autopsy surveillance, it is important to consider the best way to design sustainable systems for data collection. Electronic data capture has the potential to greatly reduce the time and costs associated with data collection. For long-term, large-scale surveillance required by national vital statistical systems, electronic data capture reduces costs and allows data to be available sooner.

Considerations for use of dental photography and electronic media in dental education and clinical practice.

PubMed

Stieber, Jane C; Nelson, Travis; Huebner, Colleen E

2015-04-01

Photography and electronic media are indispensable tools for dental education and clinical practice. Although previous research has focused on privacy issues and general strategies to protect patient privacy when sharing clinical photographs for educational purposes, there are no published recommendations for developing a functional, privacy-compliant institutional framework for the capture, storage, transfer, and use of clinical photographs and other electronic media. The aims of this study were to research patient rights relating to electronic media and propose a framework for the use of patient media in education and clinical care. After a review of the relevant literature and consultation with the University of Washington's director of privacy and compliance and assistant attorney general, the researchers developed a privacy-compliant framework to ensure appropriate capture, storage, transfer, and use of clinical photography and electronic media. A four-part framework was created to guide the use of patient media that reflects considerations of patient autonomy and privacy, informed consent, capture and storage of media, and its transfer, use, and display. The best practices proposed for capture, storage, transfer, and use of clinical photographs and electronic media adhere to the health care code of ethics (based on patient autonomy, nonmaleficence, beneficence, justice, and veracity), which is most effectively upheld by a practical framework designed to protect patients and limit institutional liability. Educators have the opportunity and duty to convey these principles to students who will become the next generation of dentists, researchers, and educators.

Dynamics of the cascade capture of electrons by charged donors in GaAs and InP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aleshkin, V. Ya., E-mail: aleshkin@ipmras.ru; Gavrilenko, L. V.

2016-08-15

The times for the cascade capture of an electron by a charged impurity have been calculated for pulsed and stationary excitations of impurity photoconductivity in GaAs and InP. The characteristic capture times under pulsed and continuous excitations are shown to differ noticeably both from each other and from the value given by the Abakumov–Perel–Yassievich formula for a charged impurity concentration greater than 10{sup 10} cm{sup –3}. The cause of this difference has been established. The Abakumov–Perel–Yassievich formula for the cascade capture cross section in the case of stationary excitation has been generalized. The dependences of the cascade capture rate onmore » the charged impurity concentration in GaAs and InP have been found for three temperatures in the case of pulsed excitation.« less

Introducing electron capture into the unitary-convolution-approximation energy-loss theory at low velocities

NASA Astrophysics Data System (ADS)

Schiwietz, G.; Grande, P. L.

2011-11-01

Recent developments in the theoretical treatment of electronic energy losses of bare and screened ions in gases are presented. Specifically, the unitary-convolution-approximation (UCA) stopping-power model has proven its strengths for the determination of nonequilibrium effects for light as well as heavy projectiles at intermediate to high projectile velocities. The focus of this contribution will be on the UCA and its extension to specific projectile energies far below 100 keV/u, by considering electron-capture contributions at charge-equilibrium conditions.

HST High Gain Antennae photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-04

S61-E-021 (7 Dec 1993) --- This close-up view of one of two High Gain Antennae (HGA) on the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. Endeavour's crew captured the HST on December 4, 1993 in order to service the telescope over a period of five days. Four of the crew members have been working in alternating pairs outside Endeavour's shirt sleeve environment to service the giant telescope. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Hubble Space Telescope photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-04

S61-E-001 (4 Dec 1993) --- This medium close-up view of the top portion of the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. Endeavour's crew captured the HST on December 4, 1993 in order to service the telescope over a period of five days. Four of the crew members will work in alternating pairs outside Endeavour's shirt sleeve environment to service the giant telescope. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

HST Solar Arrays photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-07

S61-E-020 (7 Dec 1993) --- This close-up view of one of two Solar Arrays (SA) on the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. Endeavour's crew captured the HST on December 4, 1993, in order to service the telescope over a period of five days. Four of the crew members will work in alternating pairs outside Endeavour's shirt sleeve environment to service the giant telescope. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Isomer depletion as experimental evidence of nuclear excitation by electron capture

NASA Astrophysics Data System (ADS)

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

2018-02-01

The atomic nucleus and its electrons are often thought of as independent systems that are held together in the atom by their mutual attraction. Their interaction, however, leads to other important effects, such as providing an additional decay mode for excited nuclear states, whereby the nucleus releases energy by ejecting an atomic electron instead of by emitting a γ-ray. This ‘internal conversion’ has been known for about a hundred years and can be used to study nuclei and their interaction with their electrons. In the inverse process—nuclear excitation by electron capture (NEEC)—a free electron is captured into an atomic vacancy and can excite the nucleus to a higher-energy state, provided that the kinetic energy of the free electron plus the magnitude of its binding energy once captured matches the nuclear energy difference between the two states. NEEC was predicted in 1976 and has not hitherto been observed. Here we report evidence of NEEC in molybdenum-93 and determine the probability and cross-section for the process in a beam-based experimental scenario. Our results provide a standard for the assessment of theoretical models relevant to NEEC, which predict cross-sections that span many orders of magnitude. The greatest practical effect of the NEEC process may be on the survival of nuclei in stellar environments, in which it could excite isomers (that is, long-lived nuclear states) to shorter-lived states. Such excitations may reduce the abundance of the isotope after its production. This is an example of ‘isomer depletion’, which has been investigated previously through other reactions, but is used here to obtain evidence for NEEC.

Improved search for two-neutrino double electron capture on 124Xe and 126Xe using particle identification in XMASS-I

NASA Astrophysics Data System (ADS)

Xmass Collaboration; Abe, K.; Hiraide, K.; Ichimura, K.; Kishimoto, Y.; Kobayashi, K.; Kobayashi, M.; Moriyama, S.; Nakahata, M.; Norita, T.; Ogawa, H.; Sato, K.; Sekiya, H.; Takachio, O.; Takeda, A.; Tasaka, S.; Yamashita, M.; Yang, B. S.; Kim, N. Y.; Kim, Y. D.; Itow, Y.; Kanzawa, K.; Kegasa, R.; Masuda, K.; Takiya, H.; Fushimi, K.; Kanzaki, G.; Martens, K.; Suzuki, Y.; Xu, B. D.; Fujita, R.; Hosokawa, K.; Miuchi, K.; Oka, N.; Takeuchi, Y.; Kim, Y. H.; Lee, K. B.; Lee, M. K.; Fukuda, Y.; Miyasaka, M.; Nishijima, K.; Nakamura, S.

2018-05-01

We conducted an improved search for the simultaneous capture of two K-shell electrons on the ^{124}Xe and ^{126}Xe nuclei with emission of two neutrinos using 800.0 days of data from the XMASS-I detector. A novel method to discriminate γ-ray/X-ray or double electron capture signals from β-ray background using scintillation time profiles was developed for this search. No significant signal was found when fitting the observed energy spectra with the expected signal and background. Therefore, we set the most stringent lower limits on the half-lives at 2.1 × 10^{22} and 1.9 × 10^{22} years for ^{124}Xe and ^{126}Xe, respectively, with 90% confidence level. These limits improve upon previously reported values by a factor of 4.5.

Radiative-emission analysis in charge-exchange collisions of O6 + with argon, water, and methane

NASA Astrophysics Data System (ADS)

Leung, Anthony C. K.; Kirchner, Tom

2017-04-01

Processes of electron capture followed by Auger and radiative decay were investigated in slow ion-atom and -molecule collisions. A quantum-mechanical analysis which utilizes the basis generator method within an independent electron model was carried out for collisions of O 6 + with Ar, H2O , and CH4 at impact energies of 1.17 and 2.33 keV/amu. At these impact energies, a closure approximation in the spectral representation of the Hamiltonian for molecules was found to be necessary to yield reliable results. Total single-, double-, and triple-electron-capture cross sections obtained show good agreement with previous measurements and calculations using the classical trajectory Monte Carlo method. The corresponding emission spectra from single capture for each collision system are in satisfactory agreement with previous calculations.

Observation of negative differential capacitance (NDC) in Ti Schottky diodes on SiGe islands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rangel-Kuoppa, Victor-Tapio; Jantsch, Wolfgang; Tonkikh, Alexander

2013-12-04

The Negative Differential Capacitance (NDC) effect on Ti Schottky diodes formed on n-type Silicon samples with embedded Germanium Quantum Dots (QDs) is observed and reported. The NDC-effect is detected using capacitance-voltage (CV) method at temperatures below 200 K. It is explained by the capture of electrons in Germanium QDs. Our measurements reveal that each Ge QD captures in average eight electrons.

Electrochemical Capture and Release of CO2 in Aqueous Electrolytes Using an Organic Semiconductor Electrode

PubMed Central

2017-01-01

Developing efficient methods for capture and controlled release of carbon dioxide is crucial to any carbon capture and utilization technology. Herein we present an approach using an organic semiconductor electrode to electrochemically capture dissolved CO2 in aqueous electrolytes. The process relies on electrochemical reduction of a thin film of a naphthalene bisimide derivative, 2,7-bis(4-(2-(2-ethylhexyl)thiazol-4-yl)phenyl)benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone (NBIT). This molecule is specifically tailored to afford one-electron reversible and one-electron quasi-reversible reduction in aqueous conditions while not dissolving or degrading. The reduced NBIT reacts with CO2 to form a stable semicarbonate salt, which can be subsequently oxidized electrochemically to release CO2. The semicarbonate structure is confirmed by in situ IR spectroelectrochemistry. This process of capturing and releasing carbon dioxide can be realized in an oxygen-free environment under ambient pressure and temperature, with uptake efficiency for CO2 capture of ∼2.3 mmol g–1. This is on par with the best solution-phase amine chemical capture technologies available today. PMID:28378994

In this medium close-up view, captured by an Electronic Still Camera (ESC), the Spartan 207

NASA Technical Reports Server (NTRS)

1996-01-01

STS-77 ESC VIEW --- In this medium close-up view, captured by an Electronic Still Camera (ESC), the Spartan 207 free-flyer is held in the grasp of the Space Shuttle Endeavour's Remote Manipulator System (RMS) following its re-capture on May 21, 1996. The six-member crew has spent a portion of the early stages of the mission in various activities involving the Spartan 207 and the related Inflatable Antenna Experiment (IAE). The Spartan project is managed by NASA's Goddard Space Flight Center (GSFC) for NASA's Office of Space Science, Washington, D.C. GMT: 09:38:05.

Multiplexed electronically programmable multimode ionization detector for chromatography

DOEpatents

Wise, M.B.; Buchanan, M.V.

1988-05-19

Method and apparatus for detecting and differentiating organic compounds based on their electron affinity. An electron capture detector cell (ECD) is operated in a plurality of multiplexed electronically programmable operating modes to alter the detector response during a single sampling cycle to acquire multiple simultaneous chromatograms corresponding to each of the different operating modes. The cell is held at a constant subatmospheric pressure while the electron collection bias voltage applied to the cell is modulated electronically to allow acquisition of multiple chromatograms for a single sample elution from a chromatograph representing three distinctly different response modes. A system is provided which automatically controls the programmed application of bias pulses at different intervals and/or amplitudes to switch the detector from an ionization mode to the electron capture mode and various degrees therebetween to provide an improved means of tuning an ECD for multimode detection and improved specificity. 6 figs.

A conservative, relativistic Fokker-Planck solver for runaway electrons

NASA Astrophysics Data System (ADS)

Chacon, Luis; Taitano, W.; Tang, X.; Guo, Z.; McDevitt, C.

2017-10-01

Relativistic runaway electrons develop when electric fields surpass a critical electric field, Ec =EDvth/c 2 , with ED the Dreicer field (which is the electric field at which the whole thermal electron population runs away). Above this critical field, electron tails accelerate relativistically until they are arrested by radiative processes. In regimes above this critical electric field (but below the Dreicer field), correctly capturing the interplay between the electron thermal population and the runaway tail is key, and demands a full nonlinear relativistic Fokker-Planck treatment. In this presentation, we report on progress towards a fully conservative, implicit, adaptive implementation of the relativistic electron Fokker-Planck equation. Strict conservation properties, as well as positivity preservation, are a must to avoid spurious numerical effects, and to be able to capture tenuous electron runaway tails for fields just above Ec.

Electron Beam Analysis of Micrometeoroids Captured in Aerogel as Stardust Analogues

NASA Technical Reports Server (NTRS)

Graham, G. A.; Sheffield-Parker, J.; Bradley, P.; Kearsley, A. T.; Dai, Z. R.; Mayo, S. C.; Teslich, N.; Snead, C.; Westphal, A. J.; Ishii, H.

2005-01-01

In January 2004, NASA s Stardust spacecraft passed through the tail of Comet 81P/Wild-2. The on-board dust flux monitor instrument indicated that numerous micro- and nano-meter sized cometary dust particles were captured by the dedicated silica aerogel capture cell. The collected cometary particles will be returned to Earth in January 2006. Current Stardust analogues are: (i) Light-gas-gun accelerated individual mineral grains and carbonaceous meteoritic material in aerogels at the Stardust encounter velocity ca.approximately 6 kilometers per second. (ii) Aerogels exposed in low-Earth orbit (LEO) containing preserved cosmic dust grains. Studies of these impacts offer insight into the potential state of the captured cometary dust by Stardust and the suitability of various analytical techniques. A number of papers have discussed the application of sophisticated synchrotron analytical techniques to analyze Stardust particles. Yet much of the understanding gained on the composition and mineralogy of interplanetary dust particles (IDPs) has come from electron microscopy studies. Here we discuss the application of scanning electron microscopy (SEM) for Stardust during the preliminary phase of post-return investigations.

Electron Capture in Proton Collisions with CO.

NASA Astrophysics Data System (ADS)

Stancil, P. C.; Schultz, D. R.; Kimura, M.; Gu, J.-P.; Hirsch, G.; Buenker, R. J.; Li, Y.

1999-10-01

Electron capture by protons following collisions with carbon monoxide is studied with a variety of theoretical approaches including quantal and semiclassical molecular-orbital close-coupling (MOCC) and classical trajectory Monte Carlo (CTMC) techniques. The MOCC treatments utilize potential surfaces and couplings computed for a range of H^+-CO orientation angles and C-O separations. Results including integral, differential, electronic state-selective, and vibrational state-selective cross sections will be presented for low- to intermediate-energies. Comparison with experiment will be made where possible and the relevance of the reaction in astrophysics and atmospheric physics will be discussed.

Latch of HST aft shroud photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-04

S61-E-010 (4 Dec 1993) --- This close-up view of a latch on the minus V3 aft shroud door of the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. Endeavour's crew captured the HST on December 4, 1993 in order to service the telescope over a period of five days. Four of the crew members will work in alternating pairs outside Endeavour's shirt sleeve environment to service the giant telescope. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Latch of HST aft shroud photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-04

S61-E-005 (4 Dec 1993) --- This close-up view of a latch on the minus V3 aft shroud door of the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. Endeavour's crew captured the HST on December 4, 1993 in order to service the telescope. Over a period of five days, four of the seven crew members will work in alternating pairs outside Endeavour's shirt sleeve environment to service the giant telescope. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Latch of HST aft shroud photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-04

S61-E-004 (4 Dec 1993) --- This close-up view of a latch on the minus V3 aft shroud door of the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. Endeavour's crew captured the HST on December 4, 1993 in order to service the telescope. Over a period of five days, four of the seven crew members will work in alternating pairs outside Endeavour's shirt sleeve environment to service the giant telescope. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Ultrafast dynamics of defect-assisted electron-hole recombination in monolayer MoS2.

PubMed

Wang, Haining; Zhang, Changjian; Rana, Farhan

2015-01-14

In this Letter, we present nondegenerate ultrafast optical pump-probe studies of the carrier recombination dynamics in MoS2 monolayers. By tuning the probe to wavelengths much longer than the exciton line, we make the probe transmission sensitive to the total population of photoexcited electrons and holes. Our measurement reveals two distinct time scales over which the photoexcited electrons and holes recombine; a fast time scale that lasts ∼ 2 ps and a slow time scale that lasts longer than ∼ 100 ps. The temperature and the pump fluence dependence of the observed carrier dynamics are consistent with defect-assisted recombination as being the dominant mechanism for electron-hole recombination in which the electrons and holes are captured by defects via Auger processes. Strong Coulomb interactions in two-dimensional atomic materials, together with strong electron and hole correlations in two-dimensional metal dichalcogenides, make Auger processes particularly effective for carrier capture by defects. We present a model for carrier recombination dynamics that quantitatively explains all features of our data for different temperatures and pump fluences. The theoretical estimates for the rate constants for Auger carrier capture are in good agreement with the experimentally determined values. Our results underscore the important role played by Auger processes in two-dimensional atomic materials.

Electron capture decay in Jovian planets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zito, R.R.; Schiferl, D.

1987-12-01

Following the commonly acknowledged fact that the decay of K-40 substantially contributes to the heating of planetary interiors, an examination is made of the possibility that interior heat in the Jovian planets and stars, where interior pressures may exceed 45 Mbar, may be generated by the pressure-accelerated electron capture decay of a variety of isotopes. The isotopes considered encompass K-40, V-50, Te-123, La-138, Al-26, and Cl-36. 19 references.

Rapid differentiation of rocky mountain spotted fever from chickenpox, measles, and enterovirus infections and bacterial meningitis by frequency-pulsed electron capture gas-liquid chromatographic analysis of sera.

PubMed Central

Brooks, J B; McDade, J E; Alley, C C

1981-01-01

Normal sera and sera from patients with Rocky Mountain spotted fever, chickenpox, enterovirus infections, measles, and Neisseria meningitidis infections were extracted with organic solvents under acidic and basic conditions and then derivatized with trichloroethanol or heptafluorobutyric anhydride-ethanol to form electron-capturing derivatives of organic acids, alcohols, and amines. The derivatives were analyzed by frequency-pulsed electron capture gas-liquid chromatography (FPEC-GLC). There were unique differences in the FPEC-GLC profiles of sera obtained from patients with these respective diseases. With Rocky Mountain spotted fever patients, typical profiles were detected as early as 1 day after onset of disease and before antibody could be detected in the serum. Rapid diagnosis of Rocky Mountain spotted fever by FPEC-GLC could permit early and effective therapy, thus preventing many deaths from this disease. PMID:7276147

Measuring θ13 in the Double Chooz experiment

NASA Astrophysics Data System (ADS)

Crum, Keith

2013-04-01

Double Chooz measures θ13 by searching for the disappearance of reactor electron antineutrinos (νe) interacting via inverse beta decay (IBD) in a liquid scintillator-based detector. The signature of IBD is the coincidence of positron annihilation followed by the capture of a neutron. Although Double Chooz was primarily designed to detect νe by searching for neutron capture on gadolinium, we can also search for neutron capture on hydrogen. We developed separate analyses for neutron capture on hydrogen and gadolinium as the two elements have different capture energies, capture lifetimes, and spatial distributions within our detector.

Identification and measurement of chlorinated organic pesticides in water by electron-capture gas chromatography

USGS Publications Warehouse

Lamar, William L.; Goerlitz, Donald F.; Law, LeRoy M.

1965-01-01

Pesticides, in minute quantities, may affect the regimen of streams, and because they may concentrate in sediments, aquatic organisms, and edible aquatic foods, their detection and their measurement in the parts-per-trillion range are considered essential. In 1964 the U.S. Geological Survey at Menlo Park, Calif., began research on methods for monitoring pesticides in water. Two systems were selected--electron-capture gas chromatography and microcoulometric-titration gas chromatography. Studies on these systems are now in progress. This report provides current information on the development and application of an electron-capture gas chromatographic procedure. This method is a convenient and extremely sensitive procedure for the detection and measurement of organic pesticides having high electron affinities, notably the chlorinated organic pesticides. The electron-affinity detector is extremely sensitive to these substances but it is not as sensitive to many other compounds. By this method, the chlorinated organic pesticide may be determined on a sample of convenient size in concentrations as low as the parts-per-trillion range. To insure greater accuracy in the identifications, the pesticides reported were separated and identified by their retention times on two different types of gas chromatographic columns.

Density functional calculations of multiphonon capture cross sections at defects in semiconductors

NASA Astrophysics Data System (ADS)

Barmparis, Georgios D.; Puzyrev, Yevgeniy S.; Zhang, X.-G.; Pantelides, Sokrates T.

2014-03-01

The theory of electron capture cross sections by multiphonon processes in semiconductors has a long and controversial history. Here we present a comprehensive theory and describe its implementation for realistic calculations. The Born-Oppenheimer and the Frank-Condon approximations are employed. The transition probability of an incoming electron is written as a product of an instantaneous electronic transition in the initial defect configuration and the line shape function (LSF) that describes the multiphonon processes that lead to lattice relaxation. The electronic matrix elements are calculated using the Projector Augmented Wave (PAW) method which yields the true wave functions while still employing a plane-wave basis. The LSF is calculated by employing a Monte Carlo method and the real phonon modes of the defect, calculated using density functional theory in the PAW scheme. Initial results of the capture cross section for a prototype system, namely a triply hydrogenated vacancy in Si are presented. The results are relevant for modeling device degradation by hot electron effects. This work is supported in part by the Samsung Advanced Institute of Technology (SAIT)'s Global Research Outreach (GRO) Program and by the LDRD program at ORNL.

Multiplexed electronically programmable multimode ionization detector for chromatography

DOEpatents

Wise, Marcus B.; Buchanan, Michelle V.

1989-01-01

Method and apparatus for detecting and differentiating organic compounds based on their electron affinity. An electron capture detector cell (ECD) is operated in a plurality of multiplexed electroncially programmable operating modes to alter the detector response during a single sampling cycle to acquire multiple simultaneous chromatograms corresponding to each of the different operating modes. The cell is held at a constant subatmospheric pressure while the electron collection bias voltage applied to the cell is modulated electronically to allow acquisition of multiple chromatograms for a single sample elution from a chromatograph representing three distinctly different response modes. A system is provided which automatically controls the programmed application of bias pulses at different intervals and/or amplitudes to switch the detector from an ionization mode to the electron capture mode and various degrees therebetween to provide an improved means of tuning an ECD for multimode detection and improved specificity.

Collective acceleration of ions in picosecond pinched electron beams

NASA Astrophysics Data System (ADS)

Baryshnikov, V. I.; Paperny, V. L.; Shipayev, I. V.

2017-10-01

Сharacteristics of intense electron-ion beams emitted by a high-voltage (280 kV) electron accelerator with a pulse duration of 200 ps and current 5 kA are studied. The capture phenomena and the subsequent collective acceleration of multi charged ions of the cathode material by the electric field of the electron beam are observed. It is shown that the electron-ion beam diameter does not exceed 30 µm therein in the case of lighter ions, and the decay of the pinched beam occurs at a shorter distance from the cathode. It is established that the ions of the cathode material Tin+ captured by the electron beam are accelerated up to an energy of  ⩽10 MeV, and the ion fluence reaches 1017 ion cm-2 in the pulse. These ions are effectively embedded into the lattice sites of the irradiated substrate (sapphire crystal), forming the luminescent areas of the micron scale.

Electron capture dissociation in a branched radio-frequency ion trap.

PubMed

Baba, Takashi; Campbell, J Larry; Le Blanc, J C Yves; Hager, James W; Thomson, Bruce A

2015-01-06

We have developed a high-throughput electron capture dissociation (ECD) device coupled to a quadrupole time-of-flight mass spectrometer using novel branched radio frequency ion trap architecture. With this device, a low-energy electron beam can be injected orthogonally into the analytical ion beam with independent control of both the ion and electron beams. While ions and electrons can interact in a "flow-through" mode, we observed a large enhancement in ECD efficiency by introducing a short ion trapping period at the region of ion and electron beam intersection. This simultaneous trapping mode still provides up to five ECD spectra per second while operating in an information-dependent acquisition workflow. Coupled to liquid chromatography (LC), this LC-ECD workflow provides good sequence coverage for both trypsin and Lys C digests of bovine serum albumin, providing ECD spectra for doubly charged precursor ions with very good efficiency.

Theoretical studies of dissociative recombination

NASA Technical Reports Server (NTRS)

Guberman, S. L.

1985-01-01

The calculation of dissociative recombination rates and cross sections over a wide temperature range by theoretical quantum chemical techniques is described. Model calculations on electron capture by diatomic ions are reported which illustrate the dependence of the rates and cross sections on electron energy, electron temperature, and vibrational temperature for three model crossings of neutral and ionic potential curves. It is shown that cross sections for recombination to the lowest vibrational level of the ion can vary by several orders of magnitude depending upon the position of the neutral and ionic potential curve crossing within the turning points of the v = 1 vibrational level. A new approach for calculating electron capture widths is reported. Ab initio calculations are described for recombination of O2(+) leading to excited O atoms.

Ultrafast charge-transfer-to-solvent dynamics of iodide in tetrahydrofuran. 2. Photoinduced electron transfer to counterions in solution.

PubMed

Bragg, Arthur E; Schwartz, Benjamin J

2008-04-24

The excited states of atomic anions in liquids are bound only by the polarization of the surrounding solvent. Thus, the electron-detachment process following excitation to one of these solvent-bound states, known as charge-transfer-to-solvent (CTTS) states, provides a useful probe of solvent structure and dynamics. These transitions and subsequent relaxation dynamics also are influenced by other factors that alter the solution environment local to the CTTS anion, including the presence of cosolutes, cosolvents, and other ions. In this paper, we examine the ultrafast CTTS dynamics of iodide in liquid tetrahydrofuran (THF) with a particular focus on how the solvent dynamics and the CTTS electron-ejection process are altered in the presence of various counterions. In weakly polar solvents such as THF, iodide salts can be strongly ion-paired in solution; the steady-state UV-visible absorption spectroscopy of various iodide salts in liquid THF indicates that the degree of ion-pairing changes from strong to weak to none as the counterion is switched from Na+ to tetrabutylammonium (t-BA+) to crown-ether-complexed Na+, respectively. In our ultrafast experiments, we have excited the I- CTTS transition of these various iodide salts at 263 nm and probed the dynamics of the CTTS-detached electrons throughout the visible and near-IR. In the previous paper of this series (Bragg, A. E.; Schwartz, B. J. J. Phys. Chem. B 2008, 112, 483-494), we found that for "counterion-free" I- (obtained by complexing Na+ with a crown ether) the CTTS electrons were ejected approximately 6 nm from their partner iodine atoms, the result of significant nonadiabatic coupling between the CTTS excited state and extended electronic states supported by the naturally existing solvent cavities in liquid THF, which also serve as pre-existing electron traps. In contrast, for the highly ion-paired NaI/THF system, we find that approximately 90% of the CTTS electrons are "captured" by a nearby Na+ to form (Na+, e-)THF "tight-contact pairs" (TCPs), which are chemically and spectroscopically distinct from both solvated neutral sodium atoms and free solvated electrons. A simple kinetic model is able to reproduce the details of the electron capture process, with 63% of the electrons captured quickly in approximately 2.3 ps, 26% captured diffusively in approximately 63 ps, and the remaining 11% escaping out into the solution on subnanosecond time scales. We also find that the majority of the CTTS electrons are ejected to within 1 or 2 nm of the Na+. This demonstrates that the presence of the nearby cation biases the relocalization of CTTS-generated electrons from I- in THF, changing the nonadiabatic coupling to the extended, cavity-supported electronic states in THF to produce a much tighter distribution of electron-ejection distances. In the case of the more loosely ion-paired t-BA+-I-/THF system, we find that only 10-15% of the CTTS-ejected electrons associate with t-BA+ to form "loose-contact pairs" (LCPs), which are characterized by a much weaker interaction between the electron and cation than occurs in TCPs. The formation of (t-BA+, e-)THF LCPs is characterized by a Coulombically induced blue shift of the free eTHF- spectrum on a approximately 5-ps time scale. We argue that the weaker interaction between t-BA+ and the parent I- results in little change to the CTTS-ejection process, so that only those electrons that happen to localize in the vicinity of t-BA+ are captured to form LCPs. Finally, we interpret the correlation between electron capture yield and counterion-induced perturbation of the I- CTTS transition as arising from changes in the distribution of ion-pair separations with cation identity, and we discuss our results in the context of relevant solution conductivity measurements.

Theory of electron capture from a hydrogen-like ion by a bare ion with extensions to inner-shell capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alston, S.G.

1982-01-01

A complete systematic derivation is given of a new approximation for the calculation of the cross section for electron capture from a hydrogen-like ion of large nuclear charge Z/sub T/e by a bare ion of charge Z/sub p/e moving with speed v. The amplitude in the wave treatment is obtained through consistent expansion in the small parameters Z/sub p//Z/sub T/ and Z/sub p/e/sup 2//hv; however, the ratio Z/sub T/e/sup 2//hv is not assumed small. Electron-target nucleus interactions are included to all orders and electron-projectile interactions were included consistently to first order so that the theory is called the strong potentialmore » Born (SPB). Following a careful analysis of the approach to the energy shell, an off-shell factor is seen to arise which does not appear in the impulse approximation (IA). The effects of this factor on the capture amplitude are explored. It is shown that, in comparison with the IA, the correct weighting of the target spectrum of intermediate states in the SPB significantly alters the 1s ..-->.. ns cross section and at the same time makes peaking approximations to the amplitude more realistic, even for intermediate velocity Z/sub p/e/sup 2//h<« less

Cryo-Scanning Electron Microscopy of Captured Cirrus Ice Particles

NASA Astrophysics Data System (ADS)

Magee, N. B.; Boaggio, K.; Bandamede, M.; Bancroft, L.; Hurler, K.

2016-12-01

We present the latest collection of high-resolution cryo-scanning electron microscopy images and microanalysis of cirrus ice particles captured by high-altitude balloon (ICE-Ball, see abstracts by K. Boaggio and M. Bandamede). Ice particle images and sublimation-residues are derived from particles captured during approximately 15 balloon flights conducted in Pennsylvania and New Jersey over the past 12 months. Measurements include 3D digital elevation model reconstructions of ice particles, and associated statistical analyses of entire particles and particle sub-facets and surfaces. This 3D analysis reveals that morphologies of most ice particles captured deviate significantly from ideal habits, and display geometric complexity and surface roughness at multiple measureable scales, ranging from 100's nanometers to 100's of microns. The presentation suggests potential a path forward for representing scattering from a realistically complex array of ice particle shapes and surfaces.

HST High Gain Antennae photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-04

S61-E-009 (4 Dec 1993) --- This view of one of two High Gain Antennae (HGA) on the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC). The scene was down linked to ground controllers soon after the Space Shuttle Endeavour caught up to the orbiting telescope 320 miles above Earth. Shown here before grapple, the HST was captured on December 4, 1993 in order to service the telescope. Over a period of five days, four of the seven STS-61 crew members will work in alternating pairs outside Endeavour's shirt sleeve environment. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

HST Solar Arrays photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-04

S61-E-002 (4 Dec 1993) --- This view, backdropped against the blackness of space shows one of two original Solar Arrays (SA) on the Hubble Space Telescope (HST). The scene was photographed from inside Endeavour's cabin with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. This view features the minus V-2 panel. Endeavour's crew captured the HST on December 4, 1993 in order to service the telescope over a period of five days. Four of the crew members will work in alternating pairs outside Endeavour's shirt sleeve environment to service the giant telescope. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

HST Solar Arrays photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-04

S61-E-003 (4 Dec 1993) --- This medium close-up view of one of two original Solar Arrays (SA) on the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. This view shows the cell side of the minus V-2 panel. Endeavour's crew captured the HST on December 4, 1993 in order to service the telescope over a period of five days. Four of the crew members will work in alternating pairs outside Endeavour's shirt sleeve environment to service the giant telescope. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Charge equilibrium and radiation of low-energy cosmic rays passing through interstellar medium

NASA Technical Reports Server (NTRS)

Rule, D. W.; Omidvar, K.

1979-01-01

The charge equilibrium and radiation of an oxygen and an iron beam in the MeV per nucleon energy range, representing a typical beam of low-energy cosmic rays passing through the interstellar medium, are considered. Electron loss of the beam has been taken into account by means of the first Born approximation, allowing for the target atom to remain unexcited or to be excited to all possible states. Electron-capture cross sections have been calculated by means of the scaled Oppenheimer-Brinkman-Kramers approximation, taking into account all atomic shells of the target atoms and capture into all excited states of the projectile. The capture and loss cross sections are found to be within 20%-30% of the existing experimental values for most of the cases considered. Radiation of the beam due to electron capture into the excited states of the ion, collisional excitation, and collisional inner-shell ionization, taking into account the fluorescence yield of the ions, has been considered. Effective X-ray production cross sections and multiplicities for the most energetic X-ray lines emitted by the Fe and O beams have been calculated, and error estimates made for the results.

Study of Gamow-Teller strength and associated weak-rates on odd-A nuclei in stellar matter

NASA Astrophysics Data System (ADS)

Majid, Muhammad; Nabi, Jameel-Un; Riaz, Muhammad

In a recent study by Cole et al. [A. L. Cole et al., Phys. Rev. C 86 (2012) 015809], it was concluded that quasi-particle random phase approximation (QRPA) calculations show larger deviations and overestimate the total experimental Gamow-Teller (GT) strength. It was also concluded that QRPA calculated electron capture rates exhibit larger deviation than those derived from the measured GT strength distributions. The main purpose of this study is to probe the findings of the Cole et al. paper. This study gives useful information on the performance of QRPA-based nuclear models. As per simulation results, the capturing of electrons that occur on medium heavy isotopes have a significant role in decreasing the ratio of electron-to-baryon content of the stellar interior during the late stages of core evolution. We report the calculation of allowed charge-changing transitions strength for odd-A fp-shell nuclei (45Sc and 55Mn) by employing the deformed pn-QRPA approach. The computed GT transition strength is compared with previous theoretical calculations and measured data. For stellar applications, the corresponding electron capture rates are computed and compared with rates using previously calculated and measured GT values. Our finding shows that our calculated results are in decent accordance with measured data. At higher stellar temperature, our calculated electron capture rates are larger than those calculated by independent particle model (IPM) and shell model. It was further concluded that at low temperature and high density regions, the positron emission weak-rates from 45Sc and 55Mn may be neglected in simulation codes.

Importance of Thomas single-electron transfer in fast p-He collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, D.; Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1 D-69126; Gudmundsson, M.

We report experimental angular differential cross sections for nonradiative single-electron capture in p-He collisions (p+ He -> H + He{sup +}) with a separate peak at the 0.47 mrad Thomas scattering angle for energies in the 1.3-12.5 MeV range. We find that the intensity of this peak scales with the projectile velocity as v{sub P}{sup -11}. This constitutes the first experimental test of the prediction from 1927 by L. H. Thomas [Proc. R. Soc. 114, 561 (1927)]. At our highest energy, the peak at the Thomas angle contributes with 13.5% to the total integrated nonradiative single-electron capture cross section.

Probing plasma wakefields using electron bunches generated from a laser wakefield accelerator

NASA Astrophysics Data System (ADS)

Zhang, C. J.; Wan, Y.; Guo, B.; Hua, J. F.; Pai, C.-H.; Li, F.; Zhang, J.; Ma, Y.; Wu, Y. P.; Xu, X. L.; Mori, W. B.; Chu, H.-H.; Wang, J.; Lu, W.; Joshi, C.

2018-04-01

We show experimental results of probing the electric field structure of plasma wakes by using femtosecond relativistic electron bunches generated from a laser wakefield accelerator. Snapshots of laser-driven linear wakes in plasmas with different densities and density gradients are captured. The spatiotemporal evolution of the wake in a plasma density up-ramp is recorded. Two parallel wakes driven by a laser with a main spot and sidelobes are identified in the experiment and reproduced in simulations. The capability of this new method for capturing the electron- and positron-driven wakes is also shown via 3D particle-in-cell simulations.

Exact Time-Dependent Exchange-Correlation Potential in Electron Scattering Processes

NASA Astrophysics Data System (ADS)

Suzuki, Yasumitsu; Lacombe, Lionel; Watanabe, Kazuyuki; Maitra, Neepa T.

2017-12-01

We identify peak and valley structures in the exact exchange-correlation potential of time-dependent density functional theory that are crucial for time-resolved electron scattering in a model one-dimensional system. These structures are completely missed by adiabatic approximations that, consequently, significantly underestimate the scattering probability. A recently proposed nonadiabatic approximation is shown to correctly capture the approach of the electron to the target when the initial Kohn-Sham state is chosen judiciously, and it is more accurate than standard adiabatic functionals but ultimately fails to accurately capture reflection. These results may explain the underestimation of scattering probabilities in some recent studies on molecules and surfaces.

Feasibility of real-time capture of routine clinical data in the electronic health record: a hospital-based, observational service-evaluation study

PubMed Central

Archbold, R Andrew; Weerackody, Roshan; Barnes, Michael R; Lee, Aaron M; Janjuha, Surjeet; Gutteridge, Charles; Robson, John; Timmis, Adam

2018-01-01

Objectives The electronic health record (EHR) is underused in the hospital setting. The aim of this service evaluation study was to respond to National Health Service (NHS) Digital’s ambition for a paperless NHS by capturing routinely collected cardiac outpatient data in the EHR to populate summary patient reports and provide a resource for audit and research. Design A PowerForm template was developed within the Cerner EHR, for real-time entry of routine clinical data by clinicians attending a cardiac outpatient clinic. Data captured within the PowerForm automatically populated a SmartTemplate to generate a view-only report that was immediately available for the patient and for electronic transmission to the referring general practitioner (GP). Results During the first 8 months, the PowerForm template was used in 61% (360/594) of consecutive outpatient referrals increasing from 42% to 77% during the course of the study. Structured patient reports were available for immediate sharing with the referring GP using Cerner Health Information Exchange technology while electronic transmission was successfully developed in a substudy of 64 cases, with direct delivery by the NHS Data Transfer Service in 29 cases and NHS mail in the remainder. In feedback, the report’s immediate availability was considered very or extremely important by >80% of the patients and GPs who were surveyed. Both groups reported preference of the patient report to the conventional typed letter. Deidentified template data for all 360 patients were successfully captured within the Trust system, confirming availability of these routinely collected outpatient data for audit and research. Conclusion Electronic template development tailored to the requirements of a specialist outpatient clinic facilitates capture of routinely collected data within the Cerner EHR. These data can be made available for audit and research. They can also be used to enhance communication by populating structured reports for immediate delivery to patients and GPs. PMID:29523565

Creation of an Accurate Algorithm to Detect Snellen Best Documented Visual Acuity from Ophthalmology Electronic Health Record Notes.

PubMed

Mbagwu, Michael; French, Dustin D; Gill, Manjot; Mitchell, Christopher; Jackson, Kathryn; Kho, Abel; Bryar, Paul J

2016-05-04

Visual acuity is the primary measure used in ophthalmology to determine how well a patient can see. Visual acuity for a single eye may be recorded in multiple ways for a single patient visit (eg, Snellen vs. Jäger units vs. font print size), and be recorded for either distance or near vision. Capturing the best documented visual acuity (BDVA) of each eye in an individual patient visit is an important step for making electronic ophthalmology clinical notes useful in research. Currently, there is limited methodology for capturing BDVA in an efficient and accurate manner from electronic health record (EHR) notes. We developed an algorithm to detect BDVA for right and left eyes from defined fields within electronic ophthalmology clinical notes. We designed an algorithm to detect the BDVA from defined fields within 295,218 ophthalmology clinical notes with visual acuity data present. About 5668 unique responses were identified and an algorithm was developed to map all of the unique responses to a structured list of Snellen visual acuities. Visual acuity was captured from a total of 295,218 ophthalmology clinical notes during the study dates. The algorithm identified all visual acuities in the defined visual acuity section for each eye and returned a single BDVA for each eye. A clinician chart review of 100 random patient notes showed a 99% accuracy detecting BDVA from these records and 1% observed error. Our algorithm successfully captures best documented Snellen distance visual acuity from ophthalmology clinical notes and transforms a variety of inputs into a structured Snellen equivalent list. Our work, to the best of our knowledge, represents the first attempt at capturing visual acuity accurately from large numbers of electronic ophthalmology notes. Use of this algorithm can benefit research groups interested in assessing visual acuity for patient centered outcome. All codes used for this study are currently available, and will be made available online at https://phekb.org.

Creation of an Accurate Algorithm to Detect Snellen Best Documented Visual Acuity from Ophthalmology Electronic Health Record Notes

PubMed Central

French, Dustin D; Gill, Manjot; Mitchell, Christopher; Jackson, Kathryn; Kho, Abel; Bryar, Paul J

2016-01-01

Background Visual acuity is the primary measure used in ophthalmology to determine how well a patient can see. Visual acuity for a single eye may be recorded in multiple ways for a single patient visit (eg, Snellen vs. Jäger units vs. font print size), and be recorded for either distance or near vision. Capturing the best documented visual acuity (BDVA) of each eye in an individual patient visit is an important step for making electronic ophthalmology clinical notes useful in research. Objective Currently, there is limited methodology for capturing BDVA in an efficient and accurate manner from electronic health record (EHR) notes. We developed an algorithm to detect BDVA for right and left eyes from defined fields within electronic ophthalmology clinical notes. Methods We designed an algorithm to detect the BDVA from defined fields within 295,218 ophthalmology clinical notes with visual acuity data present. About 5668 unique responses were identified and an algorithm was developed to map all of the unique responses to a structured list of Snellen visual acuities. Results Visual acuity was captured from a total of 295,218 ophthalmology clinical notes during the study dates. The algorithm identified all visual acuities in the defined visual acuity section for each eye and returned a single BDVA for each eye. A clinician chart review of 100 random patient notes showed a 99% accuracy detecting BDVA from these records and 1% observed error. Conclusions Our algorithm successfully captures best documented Snellen distance visual acuity from ophthalmology clinical notes and transforms a variety of inputs into a structured Snellen equivalent list. Our work, to the best of our knowledge, represents the first attempt at capturing visual acuity accurately from large numbers of electronic ophthalmology notes. Use of this algorithm can benefit research groups interested in assessing visual acuity for patient centered outcome. All codes used for this study are currently available, and will be made available online at https://phekb.org. PMID:27146002

A Highly Sensitive Method for Quantitative Determination of Abscisic Acid 1

PubMed Central

Michler, Charles H.; Lineberger, R. Daniel; Chism, Grady W.

1986-01-01

An abscisic acid derivative was formed by reaction with pentafluorobenzyl bromide which allowed highly sensitive detection by gas-liquid chromatography with electron capture detection. In comparison to the methyl ester derivative, the pentafluorobenzyl derivative of abscisic acid was four times more sensitive to electron capture detection and was stable at room temperature in the presence of ultraviolet light. Derivatization was rapid and the molecular weight of the new compound was confirmed by gas-liquid chromatography-mass spectrometry. PMID:16665076

Absolute emission cross sections for electron capture reactions of C2+, N3+, N4+ and O3+ ions in collisions with Li(2s) atoms

NASA Astrophysics Data System (ADS)

Rieger, G.; Pinnington, E. H.; Ciubotariu, C.

2000-12-01

Absolute photon emission cross sections following electron capture reactions have been measured for C2+, N3+, N4+ and O3+ ions colliding with Li(2s) atoms at keV energies. The results are compared with calculations using the extended classical over-the-barrier model by Niehaus. We explore the limits of our experimental method and present a detailed discussion of experimental errors.

Ensemble of electrophoretically captured gold nanoparticles as a fingerprint of Boltzmann velocity distribution

NASA Astrophysics Data System (ADS)

Hong, S. H.; Kang, M. G.; Lim, J. H.; Hwang, S. W.

2008-07-01

An ensemble of electrophoretically captured gold nanoparticles is exploited to fingerprint their velocity distribution in solution. The electrophoretic capture is performed using a dc biased nanogap electrode, and panoramic scanning electron microscopic images are inspected to obtain the regional density of the captured gold nanoparticles. The regional density profile along the surface of the electrode is in a quantitative agreement with the calculated density of the captured nanoparticles. The calculated density is obtained by counting, in the Boltzmann distribution, the number of nanoparticles whose thermal velocity is smaller than the electrophoretic velocity.

Scalable sensing electronics towards a motion capture suit

NASA Astrophysics Data System (ADS)

Xu, Daniel; Gisby, Todd A.; Xie, Shane; Anderson, Iain A.

2013-04-01

Being able to accurately record body motion allows complex movements to be characterised and studied. This is especially important in the film or sport coaching industry. Unfortunately, the human body has over 600 skeletal muscles, giving rise to multiple degrees of freedom. In order to accurately capture motion such as hand gestures, elbow or knee flexion and extension, vast numbers of sensors are required. Dielectric elastomer (DE) sensors are an emerging class of electroactive polymer (EAP) that is soft, lightweight and compliant. These characteristics are ideal for a motion capture suit. One challenge is to design sensing electronics that can simultaneously measure multiple sensors. This paper describes a scalable capacitive sensing device that can measure up to 8 different sensors with an update rate of 20Hz.

Characteristics of electron distributions observed during large amplitude whistler wave events in the magnetosphere

NASA Astrophysics Data System (ADS)

Wilson, L. B., III; Cattell, C. A.; Kellogg, P. J.; Goetz, K.; Wygant, J.; Breneman, A. W.; Kersten, K.

2010-12-01

We present a statistical study of the characteristics of electron distributions associated with large amplitude whistler waves inside the terrestrial magnetosphere using waveform capture data as an addition of the study by Kellogg et al., [2010b]. We identified three types of electron distributions observed simultaneously with the whistler waves including beam-like, beam/flattop, and anisotropic distributions. The whistlers exhibited different characteristics dependent upon the observed electron distributions. The majority of the waveforms observed in our study have f/fce ≤ 0.5 and are observed primarily in the radiation belts outside the plasmapause simultaneously with anisotropic electron distributions. We also present an example waveform capture of the largest magnetic field amplitude (≥ 8 nT pk-pk) whistler wave measured in the radiation belts. The majority of the largest amplitude whistlers occur during magnetically active periods (AE > 200 nT).

Theoretical investigation of the electron capture and loss processes in the collisions of He2+ + Ne.

PubMed

Hong, Xuhai; Wang, Feng; Jiao, Yalong; Su, Wenyong; Wang, Jianguo; Gou, Bingcong

2013-08-28

Based on the time-dependent density functional theory, a method is developed to study ion-atom collision dynamics, which self-consistently couples the quantum mechanical description of electron dynamics with the classical treatment of the ion motion. Employing real-time and real-space method, the coordinate space translation technique is introduced to allow one to focus on the region of target or projectile depending on the actual concerned process. The benchmark calculations are performed for the collisions of He(2+) + Ne, and the time evolution of electron density distribution is monitored, which provides interesting details of the interaction dynamics between the electrons and ion cores. The cross sections of single and many electron capture and loss have been calculated in the energy range of 1-1000 keV/amu, and the results show a good agreement with the available experiments over a wide range of impact energies.

Characteristics of Electron Distributions Observed During Large Amplitude Whistler Wave Events in the Magnetosphere

NASA Technical Reports Server (NTRS)

Wilson, Lynn B., III

2010-01-01

We present a statistical study of the characteristics of electron distributions associated with large amplitude whistler waves inside the terrestrial magnetosphere using waveform capture data as an addition of the study by Kellogg et al., [2010b]. We identified three types of electron distributions observed simultaneously with the whistler waves including beam-like, beam/flattop, and anisotropic distributions. The whistlers exhibited different characteristics dependent upon the observed electron distributions. The majority of the waveforms observed in our study have f/fce < or = 0.5 and are observed primarily in the radiation belts outside the plasmapause simultaneously with anisotropic electron distributions. We also present an example waveform capture of the largest magnetic field amplitude (> or = 8 nT pk-pk) whistler wave measured in the radiation belts. The majority of the largest amplitude whistlers occur during magnetically active periods (AE > 200 nT).

Double-shot MeV electron diffraction and microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musumeci, P.; Cesar, D.; Maxson, J.

Here in this paper, we study by numerical simulations a time-resolved MeV electron scattering mode where two consecutive electron pulses are used to capture the evolution of a material sample on 10 ps time scales. The two electron pulses are generated by illuminating a photocathode in a radiofrequency photogun by two short laser pulses with adjustable delay. A streak camera/deflecting cavity is used after the sample to project the two electron bunches on two well separated regions of the detector screen. By using sufficiently short pulses, the 2D spatial information from each snapshot can be preserved. This “double-shot” technique enablesmore » the efficient capture of irreversible dynamics in both diffraction and imaging modes. Finally, in this work, we demonstrate both modes in start-to-end simulations of the UCLA Pegasus MeV microscope column.« less

Double-shot MeV electron diffraction and microscopy

DOE PAGES

Musumeci, P.; Cesar, D.; Maxson, J.

2017-05-19

Here in this paper, we study by numerical simulations a time-resolved MeV electron scattering mode where two consecutive electron pulses are used to capture the evolution of a material sample on 10 ps time scales. The two electron pulses are generated by illuminating a photocathode in a radiofrequency photogun by two short laser pulses with adjustable delay. A streak camera/deflecting cavity is used after the sample to project the two electron bunches on two well separated regions of the detector screen. By using sufficiently short pulses, the 2D spatial information from each snapshot can be preserved. This “double-shot” technique enablesmore » the efficient capture of irreversible dynamics in both diffraction and imaging modes. Finally, in this work, we demonstrate both modes in start-to-end simulations of the UCLA Pegasus MeV microscope column.« less

Dynamic imaging with electron microscopy

ScienceCinema

Campbell, Geoffrey; McKeown, Joe; Santala, Melissa

2018-02-13

Livermore researchers have perfected an electron microscope to study fast-evolving material processes and chemical reactions. By applying engineering, microscopy, and laser expertise to the decades-old technology of electron microscopy, the dynamic transmission electron microscope (DTEM) team has developed a technique that can capture images of phenomena that are both very small and very fast. DTEM uses a precisely timed laser pulse to achieve a short but intense electron beam for imaging. When synchronized with a dynamic event in the microscope's field of view, DTEM allows scientists to record and measure material changes in action. A new movie-mode capability, which earned a 2013 R&D 100 Award from R&D Magazine, uses up to nine laser pulses to sequentially capture fast, irreversible, even one-of-a-kind material changes at the nanometer scale. DTEM projects are advancing basic and applied materials research, including such areas as nanostructure growth, phase transformations, and chemical reactions.

Protection of DNA against low-energy electrons by amino acids: a first-principles molecular dynamics study.

PubMed

Gu, Bin; Smyth, Maeve; Kohanoff, Jorge

2014-11-28

Using first-principles molecular dynamics simulations, we have investigated the notion that amino acids can play a protective role when DNA is exposed to excess electrons produced by ionizing radiation. In this study we focus on the interaction of glycine with the DNA nucleobase thymine. We studied thymine-glycine dimers and a condensed phase model consisting of one thymine molecule solvated in amorphous glycine. Our results show that the amino acid acts as a protective agent for the nucleobase in two ways. If the excess electron is initially captured by the thymine, then a proton is transferred in a barrier-less way from a neighboring hydrogen-bonded glycine. This stabilizes the excess electron by reducing the net partial charge on the thymine. In the second mechanism the excess electron is captured by a glycine, which acts as a electron scavenger that prevents electron localization in DNA. Both these mechanisms introduce obstacles to further reactions of the excess electron within a DNA strand, e.g. by raising the free energy barrier associated with strand breaks.

Super-AGB Stars and their Role as Electron Capture Supernova Progenitors

NASA Astrophysics Data System (ADS)

Doherty, Carolyn L.; Gil-Pons, Pilar; Siess, Lionel; Lattanzio, John C.

2017-11-01

We review the lives, deaths and nucleosynthetic signatures of intermediate-mass stars in the range ≈6-12 M⊙, which form super-AGB stars near the end of their lives. The critical mass boundaries both between different types of massive white dwarfs (CO, CO-Ne, ONe), and between white dwarfs and supernovae, are examined along with the relative fraction of super-AGB stars that end life either as an ONe white dwarf or as a neutron star (or an ONeFe white dwarf), after undergoing an electron capture supernova event. The contribution of the other potential single-star channel to electron-capture supernovae, that of the failed massive stars, is also discussed. The factors that influence these different final fates and mass limits, such as composition, rotation, the efficiency of convection, the nuclear reaction rates, mass-loss rates, and third dredge-up efficiency, are described. We stress the importance of the binary evolution channels for producing electron-capture supernovae. Recent nucleosynthesis calculations and elemental yield results are discussed and a new set of s-process heavy element yields is presented. The contribution of super-AGB star nucleosynthesis is assessed within a Galactic perspective, and the (super-)AGB scenario is considered in the context of the multiple stellar populations seen in globular clusters. A brief summary of recent works on dust production is included. Last, we conclude with a discussion of the observational constraints and potential future advances for study into these stars on the low mass/high mass star boundary.

Eikonal approximation for proton-helium electron-capture processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kobayashi, K.; Toshima, N.; Ishihara, T.

1985-09-01

We calculate the capture cross sections for H/sup +/+He..-->..H+He/sup +/, treating the passive electron explicitly in a distorted-wave formalism based on the eikonal approximation. It is found that the shape of the differential cross sections is influenced considerably by the interaction between the passive electron and the incident proton, while the integrated cross sections are much less sensitive to that. The differential cross section at 293 keV agrees well with the experimental data except at extremely small scattering angles. The forward peak is reproduced well at higher energies. The integrated cross sections are in excellent agreement with experiments for themore » incident energy above 250 keV.« less

Influence of an electric field on photostimulated states in NH4BPh4 films

NASA Astrophysics Data System (ADS)

Antonova, O. V.; Nadolinny, V. A.; Il'inchik, E. A.; Trubin, S. V.

2012-10-01

The influence of an electric field on stable photostimulated triplet states of NH4BPh4 at a temperature of 77 K have been studied by EPR spectroscopy. It has been established that, on exposure to UV radiation, electron capture by traps in the band gaps takes place with formation of triplet state. After application of an electric field, triplet states are destructed because, with an increase in the applied voltage, a gradual inclination of energy bands takes place and electrons found in traps on different energy levels are released. The assumption that captured electrons are found in traps on different energy levels is confirmed by earlier studies of thermoluminescence spectra.

Electron capture dissociation of polypeptides using a 3 Tesla Fourier transform ion cyclotron resonance mass spectrometer.

PubMed

Polfer, Nicolas C; Haselmann, Kim F; Zubarev, Roman A; Langridge-Smith, Pat R R

2002-01-01

Electron capture dissociation (ECD) of polypeptides has been demonstrated using a commercially available 3 Tesla Fourier transform ion cyclotron resonance (FTICR) instrument. A conventional rhenium filament, designed for high-energy electron impact ionisation, was used to effect ECD of substance P, bee venom melittin and bovine insulin, oxidised B chain. A retarding field analysis of the effective electron kinetic energy distribution entering the ICR cell suggests that one of the most important parameters governing ECD for this particular instrument is the need to employ low trapping plate voltages. This is shown to maximise the abundance of low-energy electrons. The demonstration of ECD at this relatively low magnetic field strength could offer the prospect of more routine ECD analysis for the wider research community, given the reduced cost of such magnets and (at least theoretically) the greater ease of electron/ion cloud overlap at lower field. Copyright 2002 John Wiley & Sons, Ltd.

Enhancing the routine health information system in rural southern Tanzania: successes, challenges and lessons learned.

PubMed

Maokola, W; Willey, B A; Shirima, K; Chemba, M; Armstrong Schellenberg, J R M; Mshinda, H; Alonso, P; Tanner, M; Schellenberg, D

2011-06-01

To describe and evaluate the use of handheld computers for the management of Health Management Information System data. Electronic data capture took place in 11 sentinel health centres in rural southern Tanzania. Information from children attending the outpatient department (OPD) and the Expanded Program on Immunization vaccination clinic was captured by trained local school-leavers, supported by monthly supervision visits. Clinical data included malaria blood slides and haemoglobin colour scale results. Quality of captured data was assessed using double data entry. Malaria blood slide results from health centre laboratories were compared to those from the study's quality control laboratory. The system took 5 months to implement, and few staffings or logistical problems were encountered. Over the following 12 months (April 2006-March 2007), 7056 attendances were recorded in 9880 infants aged 2-11 months, 50% with clinical malaria. Monthly supervision visits highlighted incomplete recording of information between OPD and laboratory records, where on average 40% of laboratory visits were missing the record of their corresponding OPD visit. Quality of microscopy from health facility laboratories was lower overall than that from the quality assurance laboratory. Electronic capture of HMIS data was rapidly and successfully implemented in this resource-poor setting. Electronic capture alone did not resolve issues of data completeness, accuracy and reliability, which are essential for management, monitoring and evaluation; suggestions to monitor and improve data quality are made. © 2011 Blackwell Publishing Ltd.

Registration of Large Motion Blurred Images

DTIC Science & Technology

2016-05-09

in handling the dynamics of the capturing system, for example, a drone. CMOS sensors , used in recent times, when employed in these cameras produce...handling the dynamics of the capturing system, for example, a drone. CMOS sensors , used in recent times, when employed in these cameras produce two types...blur in the captured image when there is camera motion during exposure. However, contemporary CMOS sensors employ an electronic rolling shutter (RS

IceCube

Science.gov Websites

written the portions of the offline software and simulations that involve the electronics and calibrations resonsible for the pieces of the detector calibration and simulation that are connected to the electronics electronics that process and capture the signal produce by Cerenkov light in the photomultiplier tubes. It

Water Capture Device Signal Integration Board

NASA Technical Reports Server (NTRS)

Chamberlin, Kathryn J.; Hartnett, Andrew J.

2018-01-01

I am a junior in electrical engineering at Arizona State University, and this is my second internship at Johnson Space Center. I am an intern in the Command and Data Handling Branch of Avionics Division (EV2), my previous internship was also in EV2. During my previous internship I was assigned to the Water Capture Device payload, where I designed a prototype circuit board for the electronics system of the payload. For this internship, I have come back to the Water Capture Device project to further the work on the electronics design I completed previously. The Water Capture Device is an experimental payload to test the functionality of two different phase separators aboard the International Space Station (ISS). A phase separator sits downstream of a condensing heat exchanger (CHX) and separates the water from the air particles for environmental control on the ISS. With changing CHX technology, new phase separators are required. The goal of the project is to develop a test bed for the two phase separators to determine the best solution.

HST Solar Arrays photographed by Electronic Still Camera

NASA Technical Reports Server (NTRS)

1993-01-01

This close-up view of one of two Solar Arrays (SA) on the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and downlinked to ground controllers soon afterward. Electronic still photography is a technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality.

Electronic Teaching Portfolios: Technology Skills + Portfolio Development = Powerful Preservice Teachers.

ERIC Educational Resources Information Center

Capraro, Mary Margaret

An electronic portfolio is a collection of work captured by electronic means that serves as an exhibit of individual efforts, progress, and achievements in one or more areas. Due to rapid growth and updates in technology, keeping electronic portfolios is becoming increasingly common in a variety of educational settings. In fall 2002 at one large…

Electronic Teaching Portfolios: Technology Skills + Portfolio Development--Do They = Powerful Preservice Teachers?

ERIC Educational Resources Information Center

Capraro, Mary Margaret

2006-01-01

Electronic portfolios are a "collection of work captured by electronic means, that serves as an exhibit of individual efforts, progress, and achievements in one or more areas" (Weidmer, 1998, p. 586). Because of the rapid growth and updates in technology, keeping electronic portfolios is becoming increasingly common in a variety of educational…

Dissociative recombination of O2(+), NO(+) and N2(+)

NASA Technical Reports Server (NTRS)

Guberman, S. L.

1983-01-01

A new L(2) approach for the calculation of the threshold molecular capture width needed for the determination of DR cross sections was developed. The widths are calculated with Fermi's golden rule by substituting Rydberg orbitals for the free electron continuum coulomb orbital. It is shown that the calculated width converges exponentially as the effective principal quantum number of the Rydberg orbital increases. The threshold capture width is then easily obtained. Since atmospheric recombination involves very low energy electrons, the threshold capture widths are essential to the calculation of DR cross sections for the atmospheric species studied here. The approach described makes use of bound state computer codes already in use. A program that collects width matrix elements over CI wavefunctions for the initial and final states is described.

The Cooking and Pneumonia Study (CAPS) in Malawi: Implementation of Remote Source Data Verification

PubMed Central

Weston, William; Smedley, James; Bennett, Andrew; Mortimer, Kevin

2016-01-01

Background Source data verification (SDV) is a data monitoring procedure which compares the original records with the Case Report Form (CRF). Traditionally, on-site SDV relies on monitors making multiples visits to study sites requiring extensive resources. The Cooking And Pneumonia Study (CAPS) is a 24- month village-level cluster randomized controlled trial assessing the effectiveness of an advanced cook-stove intervention in preventing pneumonia in children under five in rural Malawi (www.capstudy.org). CAPS used smartphones to capture digital images of the original records on an electronic CRF (eCRF). In the present study, descriptive statistics are used to report the experience of electronic data capture with remote SDV in a challenging research setting in rural Malawi. Methods At three monthly intervals, fieldworkers, who were employed by CAPS, captured pneumonia data from the original records onto the eCRF. Fieldworkers also captured digital images of the original records. Once Internet connectivity was available, the data captured on the eCRF and the digital images of the original records were uploaded to a web-based SDV application. This enabled SDV to be conducted remotely from the UK. We conducted SDV of the pneumonia data (occurrence, severity, and clinical indicators) recorded in the eCRF with the data in the digital images of the original records. Result 664 episodes of pneumonia were recorded after 6 months of follow-up. Of these 664 episodes, 611 (92%) had a finding of pneumonia in the original records. All digital images of the original records were clear and legible. Conclusion Electronic data capture using eCRFs on mobile technology is feasible in rural Malawi. Capturing digital images of the original records in the field allows remote SDV to be conducted efficiently and securely without requiring additional field visits. We recommend these approaches in similar settings, especially those with health endpoints. PMID:27355447

A mobile trauma database with charge capture.

PubMed

Moulton, Steve; Myung, Dan; Chary, Aron; Chen, Joshua; Agarwal, Suresh; Emhoff, Tim; Burke, Peter; Hirsch, Erwin

2005-11-01

Charge capture plays an important role in every surgical practice. We have developed and merged a custom mobile database (DB) system with our trauma registry (TRACS), to better understand our billing methods, revenue generators, and areas for improved revenue capture. The mobile database runs on handheld devices using the Windows Compact Edition platform. The front end was written in C# and the back end is SQL. The mobile database operates as a thick client; it includes active and inactive patient lists, billing screens, hot pick lists, and Current Procedural Terminology and International Classification of Diseases, Ninth Revision code sets. Microsoft Information Internet Server provides secure data transaction services between the back ends stored on each device. Traditional, hand written billing information for three of five adult trauma surgeons was averaged over a 5-month period. Electronic billing information was then collected over a 3-month period using handheld devices and the subject software application. One surgeon used the software for all 3 months, and two surgeons used it for the latter 2 months of the electronic data collection period. This electronic billing information was combined with TRACS data to determine the clinical characteristics of the trauma patients who were and were not captured using the mobile database. Total charges increased by 135%, 148%, and 228% for each of the three trauma surgeons who used the mobile DB application. The majority of additional charges were for evaluation and management services. Patients who were captured and billed at the point of care using the mobile DB had higher Injury Severity Scores, were more likely to undergo an operative procedure, and had longer lengths of stay compared with those who were not captured. Total charges more than doubled using a mobile database to bill at the point of care. A subsequent comparison of TRACS data with billing information revealed a large amount of uncaptured patient revenue. Greater familiarity and broader use of mobile database technology holds the potential for even greater revenue capture.

The Cooking and Pneumonia Study (CAPS) in Malawi: Implementation of Remote Source Data Verification.

PubMed

Weston, William; Smedley, James; Bennett, Andrew; Mortimer, Kevin

2016-01-01

Source data verification (SDV) is a data monitoring procedure which compares the original records with the Case Report Form (CRF). Traditionally, on-site SDV relies on monitors making multiples visits to study sites requiring extensive resources. The Cooking And Pneumonia Study (CAPS) is a 24- month village-level cluster randomized controlled trial assessing the effectiveness of an advanced cook-stove intervention in preventing pneumonia in children under five in rural Malawi (www.capstudy.org). CAPS used smartphones to capture digital images of the original records on an electronic CRF (eCRF). In the present study, descriptive statistics are used to report the experience of electronic data capture with remote SDV in a challenging research setting in rural Malawi. At three monthly intervals, fieldworkers, who were employed by CAPS, captured pneumonia data from the original records onto the eCRF. Fieldworkers also captured digital images of the original records. Once Internet connectivity was available, the data captured on the eCRF and the digital images of the original records were uploaded to a web-based SDV application. This enabled SDV to be conducted remotely from the UK. We conducted SDV of the pneumonia data (occurrence, severity, and clinical indicators) recorded in the eCRF with the data in the digital images of the original records. 664 episodes of pneumonia were recorded after 6 months of follow-up. Of these 664 episodes, 611 (92%) had a finding of pneumonia in the original records. All digital images of the original records were clear and legible. Electronic data capture using eCRFs on mobile technology is feasible in rural Malawi. Capturing digital images of the original records in the field allows remote SDV to be conducted efficiently and securely without requiring additional field visits. We recommend these approaches in similar settings, especially those with health endpoints.

Decay properties of Bk24397 and Bk24497

NASA Astrophysics Data System (ADS)

Ahmad, I.; Kondev, F. G.; Greene, J. P.; Zhu, S.

2018-01-01

Electron capture decays of 243Bk and 244Bk have been studied by measuring the γ -ray spectra of mass-separated sources and level structures of 243Cm and 244Cm have been deduced. In 243Cm, the electron capture population to the ground state, 1 /2+[631 ] , and 1 /2+[620 ] Nilsson states have been observed. The octupole Kπ=2- band was identified in 244Cm at 933.6 keV. In addition, spins and parities were deduced for several other states and two-quasiparticle configurations have been tentatively assigned to them.

Electron Capture in Slow Collision of He^2++H : Revisited

NASA Astrophysics Data System (ADS)

Krstic, Ps

2003-05-01

Very early experimental data (Fite et al. al., Proc. R. Soc. A 268, 527 (1962)) for He^2++H, recent ORNL measurements for Ne^2+ + H and our theoretical estimates suggest that the electron capture cross sections for these strongly exoergic collision systems drop slower toward low collision energies than expected from previous theories. We perform a theoretical study to establish and understand the true nature of this controversy. The calculations are based on the Hidden Crossings MOCC method, augmented with rotational and turning point effects.

Interactive Voice/Web Response System in clinical research

PubMed Central

Ruikar, Vrishabhsagar

2016-01-01

Emerging technologies in computer and telecommunication industry has eased the access to computer through telephone. An Interactive Voice/Web Response System (IxRS) is one of the user friendly systems for end users, with complex and tailored programs at its backend. The backend programs are specially tailored for easy understanding of users. Clinical research industry has experienced revolution in methodologies of data capture with time. Different systems have evolved toward emerging modern technologies and tools in couple of decades from past, for example, Electronic Data Capture, IxRS, electronic patient reported outcomes, etc. PMID:26952178

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dzhioev, Alan A., E-mail: dzhioev@theor.jinr.ru; Vdovin, A. I., E-mail: vdovin@theor.jinr.ru; Stoyanov, Ch., E-mail: stoyanov@inrne.bas.bg

We combine the thermal QRPA approach with the Skyrme energy density functional theory (Skyrme–TQRPA) for modelling the process of electron capture on nuclei in supernova environment. For a sample nucleus, {sup 56}Fe, the Skyrme–TQRPA approach is applied to analyze thermal effects on the strength function of GT{sub +} transitions which dominate electron capture at E{sub e} ≤ 30 MeV. Several Skyrme interactions are used in order to verify the sensitivity of the obtained results to the Skyrme force parameters. Finite-temperature cross sections are calculated and the results are comparedwith those of the other model calculations.

Probing Protein Structure and Folding in the Gas Phase by Electron Capture Dissociation

NASA Astrophysics Data System (ADS)

Schennach, Moritz; Breuker, Kathrin

2015-07-01

The established methods for the study of atom-detailed protein structure in the condensed phases, X-ray crystallography and nuclear magnetic resonance spectroscopy, have recently been complemented by new techniques by which nearly or fully desolvated protein structures are probed in gas-phase experiments. Electron capture dissociation (ECD) is unique among these as it provides residue-specific, although indirect, structural information. In this Critical Insight article, we discuss the development of ECD for the structural probing of gaseous protein ions, its potential, and limitations.

Homestead Valley, California, aftershocks (March 17-18, 1979) recorded on portable seismographs

USGS Publications Warehouse

Perry-Huston, Sue; Eberhart-Phillips, Donna

1994-01-01

A method for the determination of chlorinated organic compounds in aquatic tissue by dual capillary-column gas chromatography with electron- capture detection is described. Whole-body-fish or corbicula tissue is homogenized, Soxhlet extracted, lipid removed by gel permeation chromatography, and fractionated using alumina/silica adsorption chromatography. The extracts are analyzed by dissimilar capillary-column gas chromatography with electron-capture detection. The method reporting limits are 5 micrograms per kilogram (ug/kg) for chlorinated compounds, 50 ug/kg for polychlorinated biphenyls, and 200 ug/kg for toxaphene.

Interactive Voice/Web Response System in clinical research.

PubMed

Ruikar, Vrishabhsagar

2016-01-01

Emerging technologies in computer and telecommunication industry has eased the access to computer through telephone. An Interactive Voice/Web Response System (IxRS) is one of the user friendly systems for end users, with complex and tailored programs at its backend. The backend programs are specially tailored for easy understanding of users. Clinical research industry has experienced revolution in methodologies of data capture with time. Different systems have evolved toward emerging modern technologies and tools in couple of decades from past, for example, Electronic Data Capture, IxRS, electronic patient reported outcomes, etc.

High Dynamic Range Pixel Array Detector for Scanning Transmission Electron Microscopy.

PubMed

Tate, Mark W; Purohit, Prafull; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert; Chang, Celesta S; Deb, Pratiti; Turgut, Emrah; Heron, John T; Schlom, Darrell G; Ralph, Daniel C; Fuchs, Gregory D; Shanks, Katherine S; Philipp, Hugh T; Muller, David A; Gruner, Sol M

2016-02-01

We describe a hybrid pixel array detector (electron microscope pixel array detector, or EMPAD) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128×128 pixel detector consists of a 500 µm thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. This paper describes the detector architecture, data acquisition system, and preliminary results from experiments with 80-200 keV electron beams.

Dipole-Guided Electron Capture Causes Abnormal Dissociations of Phosphorylated Pentapeptides

NASA Astrophysics Data System (ADS)

Moss, Christopher L.; Chung, Thomas W.; Wyer, Jean A.; Nielsen, Steen Brøndsted; Hvelplund, Preben; Tureček, František

2011-04-01

Electron transfer and capture mass spectra of a series of doubly charged ions that were phosphorylated pentapeptides of a tryptic type (pS,A,A,A,R) showed conspicuous differences in dissociations of charge-reduced ions. Electron transfer from both gaseous cesium atoms at 100 keV kinetic energies and fluoranthene anion radicals in an ion trap resulted in the loss of a hydrogen atom, ammonia, and backbone cleavages forming complete series of sequence z ions. Elimination of phosphoric acid was negligible. In contrast, capture of low-energy electrons by doubly charged ions in a Penning ion trap induced loss of a hydrogen atom followed by elimination of phosphoric acid as the dominant dissociation channel. Backbone dissociations of charge-reduced ions also occurred but were accompanied by extensive fragmentation of the primary products. z-Ions that were terminated with a deaminated phosphoserine radical competitively eliminated phosphoric acid and H2PO4 radicals. A mechanism is proposed for this novel dissociation on the basis of a computational analysis of reaction pathways and transition states. Electronic structure theory calculations in combination with extensive molecular dynamics mapping of the potential energy surface provided structures for the precursor phosphopeptide dications. Electron attachment produces a multitude of low lying electronic states in charge-reduced ions that determine their reactivity in backbone dissociations and H- atom loss. The predominant loss of H atoms in ECD is explained by a distortion of the Rydberg orbital space by the strong dipolar field of the peptide dication framework. The dipolar field steers the incoming electron to preferentially attach to the positively charged arginine side chain to form guanidinium radicals and trigger their dissociations.

Analysis of microscopic parameters of surface charging in polymer caused by defocused electron beam irradiation.

PubMed

Liu, Jing; Zhang, Hai-Bo

2014-12-01

The relationship between microscopic parameters and polymer charging caused by defocused electron beam irradiation is investigated using a dynamic scattering-transport model. The dynamic charging process of an irradiated polymer using a defocused 30 keV electron beam is conducted. In this study, the space charge distribution with a 30 keV non-penetrating e-beam is negative and supported by some existing experimental data. The internal potential is negative, but relatively high near the surface, and it decreases to a maximum negative value at z=6 μm and finally tend to 0 at the bottom of film. The leakage current and the surface potential behave similarly, and the secondary electron and leakage currents follow the charging equilibrium condition. The surface potential decreases with increasing beam current density, trap concentration, capture cross section, film thickness and electron-hole recombination rate, but with decreasing electron mobility and electron energy. The total charge density increases with increasing beam current density, trap concentration, capture cross section, film thickness and electron-hole recombination rate, but with decreasing electron mobility and electron energy. This study shows a comprehensive analysis of microscopic factors of surface charging characteristics in an electron-based surface microscopy and analysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

IODIDE AEROSOL SORBENTS FOR MERCURY CAPTURE IN COMBUSTION EXHAUSTS

EPA Science Inventory

Several sorbent processes are being studied for their feasibility for mercury capture. Mercury is different from the other heavy metals as it is not as chemically reactive (due to a filled outer electronic shell), thus making it difficult for sorbents to chemically trap it (a). ...

Electron capture in collisions of S4+ with helium

NASA Astrophysics Data System (ADS)

Wang, J. G.; Turner, A. R.; Cooper, D. L.; Schultz, D. R.; Rakovic, M. J.; Fritsch, W.; Stancil, P. C.; Zygelman, B.

2002-07-01

Charge transfer due to collisions of ground-state S4+(3s2 1S) ions with helium is investigated for energies between 0.1 meV u-1 and 10 MeV u-1. Total and state-selective single electron capture (SEC) cross sections and rate coefficients are obtained utilizing the quantum mechanical molecular-orbital close-coupling (MOCC), atomic-orbital close-coupling (AOCC), classical trajectory Monte Carlo (CTMC) and continuum distorted wave methods. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained with the spin-coupled valence-bond approach. Previous data are limited to a calculation of the total SEC rate coefficient using the Landau-Zener model that is, in comparison to the results presented here, three orders of magnitude smaller. The MOCC SEC cross sections at low energy reveal a multichannel interference effect. True double capture is also investigated with the AOCC and CTMC approaches while autoionizing double capture and transfer ionization (TI) is explored with CTMC. SEC is found to be the dominant process except for E>200 keV u-1 when TI becomes the primary capture channel. Astrophysical implications are briefly discussed.

Advancing medical device innovation through collaboration and coordination of structured data capture pilots: Report from the Medical Device Epidemiology Network (MDEpiNet) Specific, Measurable, Achievable, Results-Oriented, Time Bound (SMART) Think Tank.

PubMed

Reed, Terrie L; Drozda, Joseph P; Baskin, Kevin M; Tcheng, James; Conway, Karen; Wilson, Natalia; Marinac-Dabic, Danica; Heise, Theodore; Krucoff, Mitchell W

2017-12-01

The Medical Device Epidemiology Network (MDEpiNet) is a public private partnership (PPP) that provides a platform for collaboration on medical device evaluation and depth of expertise for supporting pilots to capture, exchange and use device information for improving device safety and protecting public health. The MDEpiNet SMART Think Tank, held in February, 2013, sought to engage expert stakeholders who were committed to improving the capture of device data, including Unique Device Identification (UDI), in key electronic health information. Prior to the Think Tank there was limited collaboration among stakeholders beyond a few single health care organizations engaged in electronic capture and exchange of device data. The Think Tank resulted in what has become two sustainable multi-stakeholder device data capture initiatives, BUILD and VANGUARD. These initiatives continue to mature within the MDEpiNet PPP structure and are well aligned with the goals outlined in recent FDA-initiated National Medical Device Planning Board and Medical Device Registry Task Force white papers as well as the vision for the National Evaluation System for health Technology.%. Published by Elsevier Inc.

Tuning anion-functionalized ionic liquids for improved SO2 capture.

PubMed

Cui, Guokai; Zheng, Junjie; Luo, Xiaoyan; Lin, Wenjun; Ding, Fang; Li, Haoran; Wang, Congmin

2013-09-27

You can have your cake and eat it too: A "dual-tuning" strategy for improving the capture of SO2 was developed by introducing electron-withdrawing sites on the anions to produce several kinds of functionalized ionic liquids. Those functionalized with a halogen group exhibited improved performance over their non-halogenated counterparts, leading to highly efficient and reversible capture. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of a mandatory quality assurance data capture in anesthesia: a secure electronic system to capture quality assurance information linked to an automated anesthesia record.

PubMed

Peterfreund, Robert A; Driscoll, William D; Walsh, John L; Subramanian, Aparna; Anupama, Shaji; Weaver, Melissa; Morris, Theresa; Arnholz, Sarah; Zheng, Hui; Pierce, Eric T; Spring, Stephen F

2011-05-01

Efforts to assure high-quality, safe, clinical care depend upon capturing information about near-miss and adverse outcome events. Inconsistent or unreliable information capture, especially for infrequent events, compromises attempts to analyze events in quantitative terms, understand their implications, and assess corrective efforts. To enhance reporting, we developed a secure, electronic, mandatory system for reporting quality assurance data linked to our electronic anesthesia record. We used the capabilities of our anesthesia information management system (AIMS) in conjunction with internally developed, secure, intranet-based, Web application software. The application is implemented with a backend allowing robust data storage, retrieval, data analysis, and reporting capabilities. We customized a feature within the AIMS software to create a hard stop in the documentation workflow before the end of anesthesia care time stamp for every case. The software forces the anesthesia provider to access the separate quality assurance data collection program, which provides a checklist for targeted clinical events and a free text option. After completing the event collection program, the software automatically returns the clinician to the AIMS to finalize the anesthesia record. The number of events captured by the departmental quality assurance office increased by 92% (95% confidence interval [CI] 60.4%-130%) after system implementation. The major contributor to this increase was the new electronic system. This increase has been sustained over the initial 12 full months after implementation. Under our reporting criteria, the overall rate of clinical events reported by any method was 471 events out of 55,382 cases or 0.85% (95% CI 0.78% to 0.93%). The new system collected 67% of these events (95% confidence interval 63%-71%). We demonstrate the implementation in an academic anesthesia department of a secure clinical event reporting system linked to an AIMS. The system enforces entry of quality assurance information (either no clinical event or notification of a clinical event). System implementation resulted in capturing nearly twice the number of events at a relatively steady case load. © 2011 International Anesthesia Research Society

Strong-potential Born calculations for electron capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGuire, J.H.; Sil, N.C.

1983-12-01

A closed-form expression for 1s-1s electron capture has been developed in the strong-potential Born (SPB) approximation. Terms of the order (Z/sub p//v)/sup 2/ are ignored in our expression, where Z/sub p/ is the charge of the projectile and v is the collision velocity. Our errors of order (Z/sub p//v)/sup 2/ are within the accuracy of the SPB approximation itself, which is valid to first order in the projectile-electron interaction V/sub p/ (and all orders in the stronger target potential V/sub T/). Calculations using our expression are in better agreement with experimental observations of the shape of the Thomas peak thanmore » are other calculations.« less

Methods of DNA methylation detection

NASA Technical Reports Server (NTRS)

Maki, Wusi Chen (Inventor); Filanoski, Brian John (Inventor); Mishra, Nirankar (Inventor); Rastogi, Shiva (Inventor)

2010-01-01

The present invention provides for methods of DNA methylation detection. The present invention provides for methods of generating and detecting specific electronic signals that report the methylation status of targeted DNA molecules in biological samples.Two methods are described, direct and indirect detection of methylated DNA molecules in a nano transistor based device. In the direct detection, methylated target DNA molecules are captured on the sensing surface resulting in changes in the electrical properties of a nano transistor. These changes generate detectable electronic signals. In the indirect detection, antibody-DNA conjugates are used to identify methylated DNA molecules. RNA signal molecules are generated through an in vitro transcription process. These RNA molecules are captured on the sensing surface change the electrical properties of nano transistor thereby generating detectable electronic signals.

Demonstration of charge breeding in a compact room temperature electron beam ion trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vorobjev, G.; Sokolov, A.; Herfurth, F.

2012-05-15

For the first time, a small room-temperature electron beam ion trap (EBIT), operated with permanent magnets, was successfully used for charge breeding experiments. The relatively low magnetic field of this EBIT does not contribute to the capture of the ions; single-charged ions are only caught by the space charge potential of the electron beam. An over-barrier injection method was used to fill the EBIT's electrostatic trap with externally produced, single-charged potassium ions. Charge states as high as K{sup 19+} were reached after about a 3 s breeding time. The capture and breeding efficiencies up to 0.016(4)% for K{sup 17+} havemore » been measured.« less

Where Is the Electronic Oscillator Strength? Mapping Oscillator Strength across Molecular Absorption Spectra.

PubMed

Zheng, Lianjun; Polizzi, Nicholas F; Dave, Adarsh R; Migliore, Agostino; Beratan, David N

2016-03-24

The effectiveness of solar energy capture and conversion materials derives from their ability to absorb light and to transform the excitation energy into energy stored in free carriers or chemical bonds. The Thomas-Reiche-Kuhn (TRK) sum rule mandates that the integrated (electronic) oscillator strength of an absorber equals the total number of electrons in the structure. Typical molecular chromophores place only about 1% of their oscillator strength in the UV-vis window, so individual chromophores operate at about 1% of their theoretical limit. We explore the distribution of oscillator strength as a function of excitation energy to understand this circumstance. To this aim, we use familiar independent-electron model Hamiltonians as well as first-principles electronic structure methods. While model Hamiltonians capture the qualitative electronic spectra associated with π electron chromophores, these Hamiltonians mistakenly focus the oscillator strength in the fewest low-energy transitions. Advanced electronic structure methods, in contrast, spread the oscillator strength over a very wide excitation energy range, including transitions to Rydberg and continuum states, consistent with experiment. Our analysis rationalizes the low oscillator strength in the UV-vis spectral region in molecules, a step toward the goal of oscillator strength manipulation and focusing.

Electron capture and transport mediated by lattice solitons

NASA Astrophysics Data System (ADS)

Hennig, D.; Chetverikov, A.; Velarde, M. G.; Ebeling, W.

2007-10-01

We study electron transport in a one-dimensional molecular lattice chain. The molecules are linked by Morse interaction potentials. The electronic degree of freedom, expressed in terms of a tight binding system, is coupled to the longitudinal displacements of the molecules from their equilibrium positions along the axis of the lattice. More specifically, the distance between two sites influences in an exponential fashion the corresponding electronic transfer matrix element. We demonstrate that when an electron is injected in the undistorted lattice it causes a local deformation such that a compression results leading to a lowering of the electron’s energy below the lower edge of the band of linear states. This corresponds to self-localization of the electron due to a polaronlike effect. Then, if a traveling soliton lattice deformation is launched a distance apart from the electron’s position, upon encountering the polaronlike state it captures the latter dragging it afterwards along its path. Strikingly, even when the electron is initially uniformly distributed over the lattice sites a traveling soliton lattice deformation gathers the electronic amplitudes during its traversing of the lattice. Eventually, the electron state is strongly localized and moves coherently in unison with the soliton lattice deformation. This shows that for the achievement of coherent electron transport we need not start with the polaronic effect.

Electronic data capture and DICOM data management in multi-center clinical trials

NASA Astrophysics Data System (ADS)

Haak, Daniel; Page, Charles-E.; Deserno, Thomas M.

2016-03-01

Providing eligibility, efficacy and security evaluation by quantitative and qualitative disease findings, medical imaging has become increasingly important in clinical trials. Here, subject's data is today captured in electronic case reports forms (eCRFs), which are offered by electronic data capture (EDC) systems. However, integration of subject's medical image data into eCRFs is insufficiently supported. Neither integration of subject's digital imaging and communications in medicine (DICOM) data, nor communication with picture archiving and communication systems (PACS), is possible. This aggravates the workflow of the study personnel, in special regarding studies with distributed data capture in multiple sites. Hence, in this work, a system architecture is presented, which connects an EDC system, a PACS and a DICOM viewer via the web access to DICOM objects (WADO) protocol. The architecture is implemented using the open source tools OpenClinica, DCM4CHEE and Weasis. The eCRF forms the primary endpoint for the study personnel, where subject's image data is stored and retrieved. Background communication with the PACS is completely hidden for the users. Data privacy and consistency is ensured by automatic de-identification and re-labelling of DICOM data with context information (e.g. study and subject identifiers), respectively. The system is exemplarily demonstrated in a clinical trial, where computer tomography (CT) data is de-centrally captured from the subjects and centrally read by a chief radiologists to decide on inclusion of the subjects in the trial. Errors, latency and costs in the EDC workflow are reduced, while, a research database is implicitly built up in the background.

Characteristics of GeV Electron Bunches Accelerated by Intense Lasers in Vacuum

NASA Astrophysics Data System (ADS)

Wang, P. X.; Ho, Y. K.; Kong, Q.; Yuan, X. Q.; Cao, N.; Feng, L.

This paper studies the characteristics of GeV electron bunches driven by ultra-intense lasers in vacuum based on the mechanism of capture and violent acceleration scenario [CAS, see, e.g. J. X. Wang et al., Phys. Rev. E58, 6575 (1998)], which shows an interesting prospect of becoming a new principle of laser-driven accelerators. It has been found that the accelerated GeV electron bunch is a macro-pulse composed of a lot of micro-pulses, which is analogous to the structure of the bunches produced by conventional linacs. The macro-pulse corresponds to the duration of the laser pulse while the micro-pulse corresponds to the periodicity of the laser wave. Therefore, provided that the incoming electron bunch with comparable sizes as that of the laser pulse synchronously impinges on the laser pulse, the total fraction of electrons captured and accelerated to GeV energy can reach more than 20%. These results demonstrate that the mechanisms of CAS is a relatively effective accelerator mechanism.

4D multiple-cathode ultrafast electron microscopy

PubMed Central

Baskin, John Spencer; Liu, Haihua; Zewail, Ahmed H.

2014-01-01

Four-dimensional multiple-cathode ultrafast electron microscopy is developed to enable the capture of multiple images at ultrashort time intervals for a single microscopic dynamic process. The dynamic process is initiated in the specimen by one femtosecond light pulse and probed by multiple packets of electrons generated by one UV laser pulse impinging on multiple, spatially distinct, cathode surfaces. Each packet is distinctly recorded, with timing and detector location controlled by the cathode configuration. In the first demonstration, two packets of electrons on each image frame (of the CCD) probe different times, separated by 19 picoseconds, in the evolution of the diffraction of a gold film following femtosecond heating. Future elaborations of this concept to extend its capabilities and expand the range of applications of 4D ultrafast electron microscopy are discussed. The proof-of-principle demonstration reported here provides a path toward the imaging of irreversible ultrafast phenomena of materials, and opens the door to studies involving the single-frame capture of ultrafast dynamics using single-pump/multiple-probe, embedded stroboscopic imaging. PMID:25006261

4D multiple-cathode ultrafast electron microscopy.

PubMed

Baskin, John Spencer; Liu, Haihua; Zewail, Ahmed H

2014-07-22

Four-dimensional multiple-cathode ultrafast electron microscopy is developed to enable the capture of multiple images at ultrashort time intervals for a single microscopic dynamic process. The dynamic process is initiated in the specimen by one femtosecond light pulse and probed by multiple packets of electrons generated by one UV laser pulse impinging on multiple, spatially distinct, cathode surfaces. Each packet is distinctly recorded, with timing and detector location controlled by the cathode configuration. In the first demonstration, two packets of electrons on each image frame (of the CCD) probe different times, separated by 19 picoseconds, in the evolution of the diffraction of a gold film following femtosecond heating. Future elaborations of this concept to extend its capabilities and expand the range of applications of 4D ultrafast electron microscopy are discussed. The proof-of-principle demonstration reported here provides a path toward the imaging of irreversible ultrafast phenomena of materials, and opens the door to studies involving the single-frame capture of ultrafast dynamics using single-pump/multiple-probe, embedded stroboscopic imaging.

Magnetic removal of Entamoeba cysts from water using chitosan oligosaccharide-coated iron oxide nanoparticles

PubMed Central

Shukla, Sudeep; Arora, Vikas; Jadaun, Alka; Kumar, Jitender; Singh, Nishant; Jain, Vinod Kumar

2015-01-01

Amebiasis, a major health problem in developing countries, is the second most common cause of death due to parasitic infection. Amebiasis is usually transmitted by the ingestion of Entamoeba histolytica cysts through oral–fecal route. Herein, we report on the use of chitosan oligosaccharide-functionalized iron oxide nanoparticles for efficient capture and removal of pathogenic protozoan cysts under the influence of an external magnetic field. These nanoparticles were synthesized through a chemical synthesis process. The synthesized particles were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and zeta potential analysis. The particles were found to be well dispersed and uniform in size. The capture and removal of pathogenic cysts were demonstrated by fluorescent microscopy, transmission electron microscopy, and scanning electron microscopy (SEM). Three-dimensional modeling of various biochemical components of cyst walls, and thereafter, flexible docking studies demonstrate the probable interaction mechanism of nanoparticles with various components of E. histolytica cyst walls. Results of the present study suggest that E. histolytica cysts can be efficiently captured and removed from contaminated aqueous systems through the application of synthesized nanoparticles. PMID:26261417

High-yield positron systems for linear colliders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clendenin, J.E.

1989-04-01

Linear colliders, such as the SLC, are among those accelerators for which a high-yield positron source operating at the repetition rate of the accelerator is desired. The SLC, having electron energies up to 50 GeV, presents the possibility of generating positron bunches with useful charge even exceeding that of the initial electron bunch. The exact positron yield to be obtained depends on the particular capture, transport and damping system employed. Using 31 GeV electrons impinging on a W-type converter phase-space at the target to the acceptance of the capture rf section, the SLC source is capable of producing, for everymore » electron, up to two positrons within the acceptance of the positron damping ring. The design of this source and the performance of the positron system as built are described. Also, future prospects and limitations for high-yield positron systems are discussed. 11 refs., 5 figs., 3 tabs.« less

The Feasibility of Digital Pen and Paper Technology for Vital Sign Data Capture in Acute Care Settings

PubMed Central

Dykes, Patricia C.; Benoit, Angela; Chang, Frank; Gallagher, Joan; Li, Qi; Spurr, Cindy; McGrath, E. Jan; Kilroy, Susan M.; Prater, Marita

2006-01-01

The transition from paper to electronic documentation systems in acute care settings is often gradual and characterized by a period in which paper and electronic processes coexist. Intermediate technologies are needed to “bridge” the gap between paper and electronic systems as a means to improve work flow efficiency through data acquisition at the point of care in structured formats to inform decision support and facilitate reuse. The purpose of this paper is to report on the findings of a study conducted on three acute care units at Brigham and Women’s Hospital and Massachusetts General Hospital in Boston, MA to evaluate the feasibility of digital pen and paper technology as a means to capture vital sign data in the context of acute care workflows and to make data available in a flow sheet in the electronic medical record. PMID:17238337

The feasibility of digital pen and paper technology for vital sign data capture in acute care settings.

PubMed

Dykes, Patricia C; Benoit, Angela; Chang, Frank; Gallagher, Joan; Li, Qi; Spurr, Cindy; McGrath, E Jan; Kilroy, Susan M; Prater, Marita

2006-01-01

The transition from paper to electronic documentation systems in acute care settings is often gradual and characterized by a period in which paper and electronic processes coexist. Intermediate technologies are needed to "bridge" the gap between paper and electronic systems as a means to improve work flow efficiency through data acquisition at the point of care in structured formats to inform decision support and facilitate reuse. The purpose of this paper is to report on the findings of a study conducted on three acute care units at Brigham and Women's Hospital and Massachusetts General Hospital in Boston, MA to evaluate the feasibility of digital pen and paper technology as a means to capture vital sign data in the context of acute care workflows and to make data available in a flow sheet in the electronic medical record.

Making Sense of Rocket Science - Building NASA's Knowledge Management Program

NASA Technical Reports Server (NTRS)

Holm, Jeanne

2002-01-01

The National Aeronautics and Space Administration (NASA) has launched a range of KM activities-from deploying intelligent "know-bots" across millions of electronic sources to ensuring tacit knowledge is transferred across generations. The strategy and implementation focuses on managing NASA's wealth of explicit knowledge, enabling remote collaboration for international teams, and enhancing capture of the key knowledge of the workforce. An in-depth view of the work being done at the Jet Propulsion Laboratory (JPL) shows the integration of academic studies and practical applications to architect, develop, and deploy KM systems in the areas of document management, electronic archives, information lifecycles, authoring environments, enterprise information portals, search engines, experts directories, collaborative tools, and in-process decision capture. These systems, together, comprise JPL's architecture to capture, organize, store, and distribute key learnings for the U.S. exploration of space.

Electron capture into large-l Rydberg states of multiply charged ions escaping from solid surfaces

NASA Astrophysics Data System (ADS)

Nedeljković, N.; Nedeljković, Lj.; Mirković, M.

2003-07-01

We have investigated the electron capture into large-l Rydberg states of multiply charged ionic projectiles (e.g., the core charges Z=6, 7, and 8) escaping solid surfaces with intermediate velocities (v≈1 a.u.) in the normal emergence geometry. A model of the nonresonant electron capture from the solid conduction band into the moving large angular-momentum Rydberg states of the ions is developed through a generalization of our results obtained previously for the low-l cases (l=0, 1, and 2). The model is based on the two-wave-function dynamics of the Demkov-Ostrovskii type. The electron exchange process is described by a mixed flux through a moving plane (“Firsov plane”), placed between the solid surface and the ionic projectile. Due to low eccentricities of the large-l Rydberg systems, the mixed flux must be evaluated through the whole Firsov plane. It is for this purpose that a suitable asymptotic method is developed. For intermediate ionic velocities and for all relevant values of the principal quantum number n≈Z, the population probability Pnl is obtained as a nonlinear l distribution. The theoretical predictions concerning the ions S VI, Cl VII, and Ar VIII are compared with the available results of the beam-foil experiments.

Two-Centre Convergent Close-Coupling Approach to Ion-Atom Collisions: Current Progress

NASA Astrophysics Data System (ADS)

Kadyrov, Alisher; Abdurakhmanov, Ilkhom; Bailey, Jackson; Bray, Igor

2016-09-01

There are two versions of the convergent close-coupling (CCC) approach to ion-atom collisions: quantum-mechanical (QM-CCC) and semi-classical (SC-CCC). Recently, both implementations have been extended to include electron-transfer channels. The SC-CCC approach has been applied to study the excitation and the electron-capture processes in proton-hydrogen collisions. The integral alignment parameter A20 for polarization of Lyman- α emission and the cross sections for excitation and electron-capture into the lowest excited states have been calculated for a wide range of the proton impact energies. It has been established that for convergence of the results a very wide range of impact parameters (typically, 0-50 a.u.) is required due to extremely long tails of transition probabilities for transitions into the 2 p states at high energies. The QM-CCC approach allowed to obtain an accurate solution of proton-hydrogen scattering problem including all underlying processes, namely, direct scattering and ionisation, and electron capture into bound and continuum states of the projectile. In this presentation we give a general overview of current progress in applications of the two-centre CCC approach to ion-atom and atom-atom collisions. The work is supported by the Australian Research Council.

Management of radioactive waste gases from PET radiopharmaceutical synthesis using cost effective capture systems integrated with a cyclotron safety system.

PubMed

Stimson, D H R; Pringle, A J; Maillet, D; King, A R; Nevin, S T; Venkatachalam, T K; Reutens, D C; Bhalla, R

2016-09-01

The emphasis on the reduction of gaseous radioactive effluent associated with PET radiochemistry laboratories has increased. Various radioactive gas capture strategies have been employed historically including expensive automated compression systems. We have implemented a new cost-effective strategy employing gas capture bags with electronic feedback that are integrated with the cyclotron safety system. Our strategy is suitable for multiple automated 18 F radiosynthesis modules and individual automated 11 C radiosynthesis modules. We describe novel gas capture systems that minimize the risk of human error and are routinely used in our facility.

Strategies to use tablet computers for collection of electronic patient-reported outcomes.

PubMed

Schick-Makaroff, Kara; Molzahn, Anita

2015-01-22

Mobile devices are increasingly being used for data collection in research. However, many researchers do not have experience in collecting data electronically. Hence, the purpose of this short report was to identify issues that emerged in a study that incorporated electronic capture of patient-reported outcomes in clinical settings, and strategies used to address the issues. The issues pertaining to electronic patient-reported outcome data collection were captured qualitatively during a study on use of electronic patient-reported outcomes in two home dialysis units. Fifty-six patients completed three surveys on tablet computers, including the Kidney Disease Quality of Life-36, the Edmonton Symptom Assessment Scale, and a satisfaction measure. Issues that arose throughout the research process were recorded during ethics reviews, implementation process, and data collection. Four core issues emerged including logistics of technology, security, institutional and financial support, and electronic design. Although use of mobile devices for data collection has many benefits, it also poses new challenges for researchers. Advance consideration of possible issues that emerge in the process, and strategies that can help address these issues, may prevent disruption and enhance validity of findings.

Comparing Solar-Flare Acceleration of >-20 MeV Protons and Electrons Above Various Energies

NASA Technical Reports Server (NTRS)

Shih, Albert Y.

2010-01-01

A large fraction (up to tens of percent) of the energy released in solar flares goes into accelerated ions and electrons, and studies indicate that these two populations have comparable energy content. RHESSI observations have shown a striking close linear correlation between the 2.223 MeV neutron-capture gamma-ray line and electron bremsstrahlung emission >300 keV, indicating that the flare acceleration of >^20 MeV protons and >300 keV electrons is roughly proportional over >3 orders of magnitude in fluence. We show that the correlations of neutron-capture line fluence with GOES class or with bremsstrahlung emission at lower energies show deviations from proportionality, primarily for flares with lower fluences. From analyzing thirteen flares, we demonstrate that there appear to be two classes of flares with high-energy acceleration: flares that exhibit only proportional acceleration of ions and electrons down to 50 keV and flares that have an additional soft, low-energy bremsstrahlung component, suggesting two separate populations of accelerated electrons. We use RHESSI spectroscopy and imaging to investigate a number of these flares in detail.

Phonon-assisted changes in charge states of deep level defects in germanium

NASA Astrophysics Data System (ADS)

Markevich, A. V.; Litvinov, V. V.; Emtsev, V. V.; Markevich, V. P.; Peaker, A. R.

2006-04-01

Electronic processes associated with changes in the charge states of the vacancy-oxygen center (VO or A center) and vacancy-group-V-impurity atom (P, As, Sb or Bi) pairs (E centers) in irradiated germanium crystals have been studied using deep level transient spectroscopy (DLTS), high-resolution Laplace DLTS and Hall effect measurements. It is found that the electron emission and capture processes related to transitions between the doubly and the singly negatively charged states of the A center and the E centers in Ge are phonon-assisted, i.e., they are accompanied by significant vibrations and re-arrangements of atoms in the vicinity of the defects. Manifestations of the phonon involvements are: (i) temperature-dependent electron capture cross-sections which are well described in the frame of the multi-phonon-assisted capture model; (ii) large changes in entropy related to the ionization of the defects and, associated with these, temperature-dependent positions of energy levels; and (iii) electron emission via phonon-assisted tunneling upon the application of electric field. These effects have been considered in detail for the vacancy-oxygen and the vacancy-donor complexes. On the basis of a combined analysis of the electronic processes a configuration-coordinate diagram of the acceptor states of the A and E centers is plotted. It is found that changes in the entropy of ionization and the energy for electron emission for these traps follow the empirical Meyer-Neldel rule. A model based on multi-phonon-assisted carrier emission from defects is adapted for the explanation of the origin of this rule for the case of electronic processes in Ge.

The electric potential of particles in interstellar space released from a nuclear waste payload

NASA Technical Reports Server (NTRS)

Williams, A. C.

1980-01-01

Mechanisms for charging a grain in the interplanetary medium include: (1) capture of solar wind electrons; (2) capture of solar wind protons; (3) ejection of electrons through the photoelectric effect due to the solar radiation; (4) escape of beta particles from beta emitters in the grain; and (5) escape of alpha particles from alpha emitters in the grain. The potentials on both nonradioactive and radioactive grains are considered with relation to particle size and time, and the distance from the Sun. Numerical results are presented where the waste mix is assumed to be PW-4b.

Cleanup procedure for water, soil, animal and plant extracts for the use of electron-capture detector in the gas chromatographic analysis of organophosphorus insecticide residues.

PubMed

Kadoum, A M

1968-07-01

A simple, aqueous acetonitrile partition cleanup method for analyses of some common organophosphorus insecticide residues is described. The procedure described is for cleanup and quantitative recovery of parathion, methyl parathion, diazinon, malathion and thimet from different extracts. Those insecticides in the purified extracts of ground water, grain, soil, plant and animal tissues can be detected quantitatively by gas chromatography with an electron capture-detector at 0.01 ppm. Cleanup is satisfactory for paper and thin-layer chromatography for further identification of individual insecticides in the extracts.

Measurement of cardiac output using improved chromatographic analysis of sulfur hexafluoride (SF6).

PubMed

Klocke, F J; Roberts, D L; Farhi, E R; Naughton, B J; Sekovski, B; Klocke, R A

1977-06-01

A constant current variable frequency pulsed electron capture detector has been incorporated into the gas chromatographic analysis of trace amounts of sulfur hexafluoride (SF6) in water and blood. The resulting system offers a broader effective operating range than more conventional electron capture units and has been utilized for measurements of cardiac output employing constant-rate infusion of dissolved SF6. The SF6 technique has been validated against direct volumetric measurements of cardiac output in a canine right-heart bypass preparation and used subsequently for rapidly repeated measurements in conscious animals and man.

Neutrino signal of electron-capture supernovae from core collapse to cooling.

PubMed

Hüdepohl, L; Müller, B; Janka, H-T; Marek, A; Raffelt, G G

2010-06-25

An 8.8M{⊙} electron-capture supernova was simulated in spherical symmetry consistently from collapse through explosion to essentially complete deleptonization of the forming neutron star. The evolution time (∼9  s) is short because high-density effects suppress our neutrino opacities. After a short phase of accretion-enhanced luminosities (∼200  ms), luminosity equipartition among all species becomes almost perfect and the spectra of ν{e} and ν{μ,τ} very similar, ruling out the neutrino-driven wind as r-process site. We also discuss consequences for neutrino flavor oscillations.

Decay properties of Bk 97 243 and Bk 97 244

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, I.; Kondev, F. G.; Greene, J. P.

2018-01-01

Electron capture decays of Bk-243 and Bk-244 have been studied by measuring the gamma-ray spectra of mass-separated sources and level structures of Cm-243 and Cm-244 have been deduced. In Cm-243, the electron capture population to the ground state, 1/2(+)[631], and 1/2(+)[620] Nilsson states have been observed. The octupole K-pi = 2(-) band was identified in Cm-244 at 933.6 keV. In addition, spins and parities were deduced for several other states and two-quasiparticle configurations have been tentatively assigned to them

Exploratory investigations of hypervelocity intact capture spectroscopy

NASA Technical Reports Server (NTRS)

Tsou, P.; Griffiths, D. J.

1993-01-01

The ability to capture hypervelocity projectiles intact opens a new technique available for hypervelocity research. A determination of the reactions taking place between the projectile and the capture medium during the process of intact capture is extremely important to an understanding of the intact capture phenomenon, to improving the capture technique, and to developing a theory describing the phenomenon. The intact capture of hypervelocity projectiles by underdense media generates spectra, characteristic of the material species of projectile and capture medium involved. Initial exploratory results into real-time characterization of hypervelocity intact capture techniques by spectroscopy include ultra-violet and visible spectra obtained by use of reflecting gratings, transmitting gratings, and prisms, and recorded by photographic and electronic means. Spectrometry proved to be a valuable real-time diagnostic tool for hypervelocity intact capture events, offering understanding of the interactions of the projectile and the capture medium during the initial period and providing information not obtainable by other characterizations. Preliminary results and analyses of spectra produced by the intact capture of hypervelocity aluminum spheres in polyethylene (PE), polystyrene (PS), and polyurethane (PU) foams are presented. Included are tentative emission species identifications, as well as gray body temperatures produced in the intact capture process.

Modeling time-coincident ultrafast electron transfer and solvation processes at molecule-semiconductor interfaces

NASA Astrophysics Data System (ADS)

Li, Lesheng; Giokas, Paul G.; Kanai, Yosuke; Moran, Andrew M.

2014-06-01

Kinetic models based on Fermi's Golden Rule are commonly employed to understand photoinduced electron transfer dynamics at molecule-semiconductor interfaces. Implicit in such second-order perturbative descriptions is the assumption that nuclear relaxation of the photoexcited electron donor is fast compared to electron injection into the semiconductor. This approximation breaks down in systems where electron transfer transitions occur on 100-fs time scale. Here, we present a fourth-order perturbative model that captures the interplay between time-coincident electron transfer and nuclear relaxation processes initiated by light absorption. The model consists of a fairly small number of parameters, which can be derived from standard spectroscopic measurements (e.g., linear absorbance, fluorescence) and/or first-principles electronic structure calculations. Insights provided by the model are illustrated for a two-level donor molecule coupled to both (i) a single acceptor level and (ii) a density of states (DOS) calculated for TiO2 using a first-principles electronic structure theory. These numerical calculations show that second-order kinetic theories fail to capture basic physical effects when the DOS exhibits narrow maxima near the energy of the molecular excited state. Overall, we conclude that the present fourth-order rate formula constitutes a rigorous and intuitive framework for understanding photoinduced electron transfer dynamics that occur on the 100-fs time scale.

HST Solar Arrays photographed by Electronic Still Camera

NASA Technical Reports Server (NTRS)

1993-01-01

This view, backdropped against the blackness of space shows one of two original Solar Arrays (SA) on the Hubble Space Telescope (HST). The scene was photographed with an Electronic Still Camera (ESC), and downlinked to ground controllers soon afterward. Electronic still photography is a technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality.

Ionization rate from the electron precipitation during August 2011 storm

NASA Astrophysics Data System (ADS)

Huang, Y.; Huang, C. Y.; Su, Y.

2013-12-01

We apply a parameterization by Fang et al. [2010] (Fang2010) to the complex energy spectra measured by DMSP F16 satellites to calculate the ionization rate from electron precipitation during a moderate storm on August 6th, 2011. The DMSP electron flux measurements show that there is clear enhancement of electron fluxes in the polar cap. The mean energy in the polar cap is mostly above 100 eV, while the mean energy of auroral zone is above 1 keV. F16 also captures a strong Poynting flux enhancement in the polar cap. The electron impact ionization rates using thermospheric densities and temperatures from NRLMSISE-00, TIE-GCM and GITM show clear enhancement at F-region altitudes in the polar cap region due to the low-energy electrons precipitated. Using the default empirical formulations of electron impact ionization in GCMs, TIE-GCM and GITM do not capture the F-region ionization shown in the results of Fang2010 parameterization. Fang, X, C. E. Randall, D. Lummerzheim, W. Wang, G. Lu, S. C. Solomon, and R. A. Frahm (2010), Geophys. Res. Lett., 37, L22106, doi:10.1029/2010GL045406.

Imaging of Endogenous Metabolites of Plant Leaves by Mass Spectrometry Based on Laser Activated Electron Tunneling.

PubMed

Huang, Lulu; Tang, Xuemei; Zhang, Wenyang; Jiang, Ruowei; Chen, Disong; Zhang, Juan; Zhong, Hongying

2016-04-07

A new mass spectrometric imaging approach based on laser activated electron tunneling (LAET) was described and applied to analysis of endogenous metabolites of plant leaves. LAET is an electron-directed soft ionization technique. Compressed thin films of semiconductor nanoparticles of bismuth cobalt zinc oxide were placed on the sample plate for proof-of-principle demonstration because they can not only absorb ultraviolet laser but also have high electron mobility. Upon laser irradiation, electrons are excited from valence bands to conduction bands. With appropriate kinetic energies, photoexcited electrons can tunnel away from the barrier and eventually be captured by charge deficient atoms present in neutral molecules. Resultant unpaired electron subsequently initiates specific chemical bond cleavage and generates ions that can be detected in negative ion mode of the mass spectrometer. LAET avoids the co-crystallization process of routinely used organic matrix materials with analyzes in MALDI (matrix assisted-laser desorption ionization) analysis. Thus uneven distribution of crystals with different sizes and shapes as well as background peaks in the low mass range resulting from matrix molecules is eliminated. Advantages of LAET imaging technique include not only improved spatial resolution but also photoelectron capture dissociation which produces predictable fragment ions.

The BlackBerry Project: Capturing the Content of Adolescents' Text Messaging

ERIC Educational Resources Information Center

Underwood, Marion K.; Rosen, Lisa H.; More, David; Ehrenreich, Samuel E.; Gentsch, Joanna K.

2012-01-01

This article presents an innovative method for capturing the content of adolescents' electronic communication on handheld devices: text messaging, e-mail, and instant messaging. In an ongoing longitudinal study, adolescents were provided with BlackBerry devices with service plans paid for by the investigators, and use of text messaging was…

Single-shot ultrabroadband two-dimensional electronic spectroscopy of the light-harvesting complex LH2.

PubMed

Harel, Elad; Long, Phillip D; Engel, Gregory S

2011-05-01

Here we present two-dimensional (2D) electronic spectra of the light-harvesting complex LH2 from purple bacteria using coherent pulses with bandwidth of over 100 nm FWHM. This broadband excitation and detection has allowed the simultaneous capture of both the B800 and B850 bands using a single light source. We demonstrate that one laser pulse is sufficient to capture the entire 2D electronic spectrum with a high signal-to-noise ratio. At a waiting time of 800 fs, we observe population transfer from the B800 to B850 band as manifested by a prominent cross peak. These results will enable observation of the dynamics of biological systems across both ultrafast (<1 ps) and slower (>1 ms) timescales simultaneously.

Radiation effects in accelerator components

NASA Astrophysics Data System (ADS)

Borden, M. J.

1995-05-01

A review of basic radiation effects is presented. The fundamental definitions of radioactivity are given for alpha, beta, positron decay, gamma-ray emission and electron capture. The interaction of neutrons with material is covered including: absorption through radiative capture, neutron-proton interaction, alpha particle emission, neutron-multi-neutron reactions and fission. Basic equations defining inelastic and elastic scattering are presented with examples of neutron energy loss per collision for several elements. Photon interactions are considered for gamma-rays and x-rays. Photoelectric collisions, the Compton effect and pair production are reviewed. Electron-proton interactions are discussed with emphasis placed on defect production. Basic displacement damage mechanisms for photon and particle interaction are presented. Several examples of radiation effects to plastics, electronics and ceramics are presented. Extended references are given for each example.

Crossing the "digital divide:" implementing an electronic medical record system in a rural Kenyan health center to support clinical care and research.

PubMed

Tierney, William M; Rotich, Joseph K; Smith, Faye E; Bii, John; Einterz, Robert M; Hannan, Terry J

2002-01-01

To improve care, one must measure it. In the US, electronic medical record systems have been installed in many institutions to support health care management, quality improvement, and research. Developing countries lack such systems and thus have difficulties managing scarce resources and investigating means of improving health care delivery and outcomes. We describe the implementation and use of the first documented electronic medical record system in ambulatory care in sub-Saharan Africa. After one year, it has captured data for more than 13,000 patients making more than 26,000 visits. We present lessons learned and modifications made to this system to improve its capture of data and ability to support a comprehensive clinical care and research agenda.

Examining Evidence-Based Content Related to Hospital Acquired Pressure Ulcer Prevention in Paper and Electronic Health Records

ERIC Educational Resources Information Center

Jaekel, Camilla M.

2012-01-01

Although there have been great advancements in the Electronic Health Record (EHR), there is a dearth of rigorous research that examines the relationship between the use of electronic documentation to capture nursing process components and the impact of consistent documentation on patient outcomes (Daly, Buckwalter & Maas, 2002; Gugerty, 2006;…

Ambient Carbon Dioxide Capture Using Boron-Rich Porous Boron Nitride: A Theoretical Study.

PubMed

Li, Lanlan; Liu, Yan; Yang, Xiaojing; Yu, Xiaofei; Fang, Yi; Li, Qiaoling; Jin, Peng; Tang, Chengchun

2017-05-10

The development of highly efficient sorbent materials for CO 2 capture under ambient conditions is of great importance for reducing the impact of CO 2 on the environment and climate change. In this account, strong CO 2 adsorption on a boron antisite (B N ) in boron-rich porous boron nitrides (p-BN) was developed and studied. The results indicated that the material achieved larger adsorption energies of 2.09 eV (201.66 kJ/mol, PBE-D). The electronic structure calculations suggested that the introduction of B N in p-BN induced defect electronic states in the energy gap region, which strongly impacted the adsorption properties of the material. The bonding between the B N defect and the CO 2 molecule was clarified, and it was found that the electron donation first occurred from CO 2 to the B N double-acceptor state then, followed by electron back-donation from B N to CO 2 accompanied by the formation of a B N -C bond. The thermodynamic properties indicated that the adsorption of CO 2 on the B N defect to form anionic CO 2 δ- species was spontaneous at temperatures below 350 K. Both the large adsorption energies and the thermodynamic properties ensured that p-BN with a B N defect could effectively capture CO 2 under ambient conditions. Finally, to evaluate the energetic stability, the defect formation energies were estimated. The formation energy of the B N defects was found to strongly depend on the chemical environment, and the selection of different reactants (B or N sources) would achieve the goal of reducing the formation energy. These findings provided a useful guidance for the design and fabrication of a porous BN sorbent for CO 2 capture.

Representing the thermal state in time-dependent density functional theory

DOE PAGES

Modine, N. A.; Hatcher, R. M.

2015-05-28

Classical molecular dynamics (MD) provides a powerful and widely used approach to determining thermodynamic properties by integrating the classical equations of motion of a system of atoms. Time-Dependent Density Functional Theory (TDDFT) provides a powerful and increasingly useful approach to integrating the quantum equations of motion for a system of electrons. TDDFT efficiently captures the unitary evolution of a many-electron state by mapping the system into a fictitious non-interacting system. In analogy to MD, one could imagine obtaining the thermodynamic properties of an electronic system from a TDDFT simulation in which the electrons are excited from their ground state bymore » a time-dependent potential and then allowed to evolve freely in time while statistical data are captured from periodic snapshots of the system. For a variety of systems (e.g., many metals), the electrons reach an effective state of internal equilibrium due to electron-electron interactions on a time scale that is short compared to electron-phonon equilibration. During the initial time-evolution of such systems following electronic excitation, electron-phonon interactions should be negligible, and therefore, TDDFT should successfully capture the internal thermalization of the electrons. However, it is unclear how TDDFT represents the resulting thermal state. In particular, the thermal state is usually represented in quantum statistical mechanics as a mixed state, while the occupations of the TDDFT wave functions are fixed by the initial state in TDDFT. Two key questions involve (1) reformulating quantum statistical mechanics so that thermodynamic expectations can be obtained as an unweighted average over a set of many-body pure states and (2) constructing a family of non-interacting (single determinant) TDDFT states that approximate the required many-body states for the canonical ensemble. In Section II, we will address these questions by first demonstrating that thermodynamic expectations can be evaluated by averaging over certain many-body pure states, which we will call thermal states, and then constructing TDDFT states that approximate these thermal states. In Section III, we will present some numerical tests of the resulting theory, and in Section IV, we will summarize our main results and discuss some possible future directions for this work.« less

Healthcare databases in Europe for studying medicine use and safety during pregnancy.

PubMed

Charlton, Rachel A; Neville, Amanda J; Jordan, Sue; Pierini, Anna; Damase-Michel, Christine; Klungsøyr, Kari; Andersen, Anne-Marie Nybo; Hansen, Anne Vinkel; Gini, Rosa; Bos, Jens H J; Puccini, Aurora; Hurault-Delarue, Caroline; Brooks, Caroline J; de Jong-van den Berg, Lolkje T W; de Vries, Corinne S

2014-06-01

The aim of this study was to describe a number of electronic healthcare databases in Europe in terms of the population covered, the source of the data captured and the availability of data on key variables required for evaluating medicine use and medicine safety during pregnancy. A sample of electronic healthcare databases that captured pregnancies and prescription data was selected on the basis of contacts within the EUROCAT network. For each participating database, a database inventory was completed. Eight databases were included, and the total population covered was 25 million. All databases recorded live births, seven captured stillbirths and five had full data available on spontaneous pregnancy losses and induced terminations. In six databases, data were usually available to determine the date of the woman's last menstrual period, whereas in the remainder, algorithms were needed to establish a best estimate for at least some pregnancies. In seven databases, it was possible to use data recorded in the databases to identify pregnancies where the offspring had a congenital anomaly. Information on confounding variables was more commonly available in databases capturing data recorded by primary-care practitioners. All databases captured maternal co-prescribing and a measure of socioeconomic status. This study suggests that within Europe, electronic healthcare databases may be valuable sources of data for evaluating medicine use and safety during pregnancy. The suitability of a particular database, however, will depend on the research question, the type of medicine to be evaluated, the prevalence of its use and any adverse outcomes of interest. © 2014 The Authors. Pharmacoepidemiology and Drug Safety published by John Wiley & Sons, Ltd. © 2014 The Authors. Pharmacoepidemiology and Drug Safety published by John Wiley & Sons, Ltd.

Efficient, quality-assured data capture in operational research through innovative use of open-access technology

PubMed Central

Naik, B.; Guddemane, D. K.; Bhat, P.; Wilson, N.; Sreenivas, A. N.; Lauritsen, J. M.; Rieder, H. L.

2013-01-01

Ensuring quality of data during electronic data capture has been one of the most neglected components of operational research. Multicentre studies are also challenged with issues about logistics of travel, training, supervision, monitoring and troubleshooting support. Allocating resources to these issues can pose a significant bottleneck for operational research in resource-limited settings. In this article, we describe an innovative and efficient way of coordinating data capture in multicentre operational research using a combination of three open access technologies—EpiData for data capture, Dropbox for sharing files and TeamViewer for providing remote support. PMID:26392997

Investigation of energy deposited by femtosecond electron transfer in collisions using hydrated ion nanocalorimetry.

PubMed

Holm, Anne I S; Donald, William A; Hvelplund, Preben; Larsen, Mikkel K; Nielsen, Steen Brøndsted; Williams, Evan R

2008-10-30

Ion nanocalorimetry is used to investigate the internal energy deposited into M (2+)(H 2O) n , M = Mg ( n = 3-11) and Ca ( n = 3-33), upon 100 keV collisions with a Cs or Ne atom target gas. Dissociation occurs by loss of water molecules from the precursor (charge retention) or by capture of an electron to form a reduced precursor (charge reduction) that can dissociate either by loss of a H atom accompanied by water molecule loss or by exclusively loss of water molecules. Formation of bare CaOH (+) and Ca (+) by these two respective dissociation pathways occurs for clusters with n up to 33 and 17, respectively. From the threshold dissociation energies for the loss of water molecules from the reduced clusters, obtained from binding energies calculated using a discrete implementation of the Thomson liquid drop model and from quantum chemistry, estimates of the internal energy deposition can be obtained. These values can be used to establish a lower limit to the maximum and average energy deposition. Not taking into account effects of a kinetic shift, over 16 eV can be deposited into Ca (2+)(H 2O) 33, the minimum energy necessary to form bare CaOH (+) from the reduced precursor. The electron capture efficiency is at least a factor of 40 greater for collisions of Ca (2+)(H 2O) 9 with Cs than with Ne, reflecting the lower ionization energy of Cs (3.9 eV) compared to Ne (21.6 eV). The branching ratio of the two electron capture dissociation pathways differs significantly for these two target gases, but the distributions of water molecules lost from the reduced precursors are similar. These results suggest that the ionization energy of the target gas has a large effect on the electron capture efficiency, but relatively little effect on the internal energy deposited into the ion. However, the different branching ratios suggest that different electronic excited states may be accessed in the reduced precursor upon collisions with these two different target gases.

Angular Distributions of Differential Electron Capture Cross Sections in Collisions Between Low-Velocity Highly-Charged Ions and Neutral Targets.

NASA Astrophysics Data System (ADS)

Waggoner, William Tracy

1990-01-01

Experimental capture cross sections d sigma / dtheta versus theta , are presented for various ions incident on neutral targets. First, distributions are presented for Ar ^{rm 8+} ions incident on H_{rm 2}, D _{rm 2}, and Ar targets. Energy gain studies indicate that capture occurs to primarily a 5d,f final state of Ar^{rm 7+} with some contributions from transfer ionization (T.I.) channels. Angular distribution spectra for all three targets are similar, with spectra having a main peak located at forward angles which is attributed to single capture events, and a secondary structure occurring at large angles which is attributed to T.I. contributions. A series of Ar^{rm 8+} on Ar spectra were collected using a retarding grid system as a low resolution energy spectrometer to resolve single capture events from T.I. events. The resulting single capture and T.I. angular distributions are presented. Results are discussed in terms of a classical deflection function employing a simple two state curve crossing model. Angular distributions for electron capture from He by C, N, O, F, and Ne ions with charge states from 5 ^+-8^+ are presented for projectile energies between 1.2 and 2.0 kV. Distributions for the same charge state but different ion species are simlar, but not identical with distributions for the 5 ^+ and 7^+ ions being strongly forward peaked, the 6^+ distributions are much less forward peaked with the O^{6+} distributions showing structure, the Ne^{8+} ion distribution appears to be an intermediate case between forward peaking and large angle scattering. These results are discussed in terms of classical deflection functions which utilize two state Coulomb diabatic curve crossing models. Finally, angular distributions are presented for electron capture from He by Ar^{rm 6+} ions at energies between 1287 eV and 296 eV. At large projectile energies the distribution is broad. As the energy decreases below 523 eV, distributions shift to forward angles with a second peak appearing outside the Coulomb angle, theta_{c} = Q/2E, which continues to grow in magnitude as the projectile energy decreases further. Results are compared with a model calculation employing a two state diabatic Coulomb curve crossing model and the classical deflection function.

Electronic capture of patient-reported and clinician-reported outcome measures in an elective orthopaedic setting: a retrospective cohort analysis.

PubMed

Malhotra, Karan; Buraimoh, Olatunbosun; Thornton, James; Cullen, Nicholas; Singh, Dishan; Goldberg, Andrew J

2016-06-20

To determine whether an entirely electronic system can be used to capture both patient-reported outcomes (electronic Patient-Reported Outcome Measures, ePROMs) as well as clinician-validated diagnostic and complexity data in an elective surgical orthopaedic outpatient setting. To examine patients' experience of this system and factors impacting their experience. Retrospective analysis of prospectively collected data. Single centre series. Outpatient clinics at an elective foot and ankle unit in the UK. All new adult patients attending elective orthopaedic outpatient clinics over a 32-month period. All patients were invited to complete ePROMs prior to attending their outpatient appointment. At their appointment, those patients who had not completed ePROMs were offered the opportunity to complete it on a tablet device with technical support. Matched diagnostic and complexity data were captured by the treating consultant during the appointment. Capture rates of patient-reported and clinician-reported data. All information and technology (IT) failures, language and disability barriers were captured. Patients were asked to rate their experience of using ePROMs. The scoring systems used included EQ-5D-5L, the Manchester-Oxford Foot Questionnaire (MOxFQ) and the Visual Analogue Scale (VAS) pain score. Out of 2534 new patients, 2176 (85.9%) completed ePROMs, of whom 1090 (50.09%) completed ePROMs at home/work prior to their appointment. 31.5% used a mobile (smartphone/tablet) device. Clinician-reported data were captured on 2491 patients (98.3%). The mean patient experience score of using Patient-Reported Outcome Measures (PROMs) was 8.55±1.85 out of 10 and 666 patients (30.61%) left comments. Of patients leaving comments, 214 (32.13%) felt ePROMs did not adequately capture their symptoms and these patients had significantly lower patient experience scores (p<0.001). This study demonstrates the successful implementation of technology into a service improvement programme. Excellent capture rates of ePROMs and clinician-validated diagnostic data can be achieved within a National Health Service setting. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

76 FR 1173 - Draft Guidance for Industry on Electronic Source Documentation in Clinical Investigations...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-07

...] Draft Guidance for Industry on Electronic Source Documentation in Clinical Investigations; Availability... Documentation in Clinical Investigations.'' This document provides guidance to sponsors, contract research organizations (CROs), data management centers, and clinical investigators on capturing, using, and archiving...

The first experimental investigation of the KLL Auger spectrum of Ni generated in the electron capture decay of radioactive 64Cu in a solid state matrix

NASA Astrophysics Data System (ADS)

Inoyatov, A. Kh.; Perevoshchikov, L. L.; Kovalík, A.; Filosofov, D. V.; Gorozhankin, V. M.; Ryšavý, M.

2012-09-01

The KLL Auger spectrum of Ni generated in the electron capture decay of radioactive 64Cu in a solid state matrix was measured for the first time using a combined electrostatic electron spectrometer adjusted to a 7 eV instrumental resolution. Energies and relative intensities of the all nine basic spectrum components were determined and compared with data obtained from X-ray induced spectra of metallic Ni and with theoretical results as well. Absolute energy of 6562.5 ± 1.3 eV (related to the Fermi level) measured for the dominant KL2L3(1D2) than a value obtained from the X-ray induced spectra which is probably caused by the effects of chemical bonding and physico-chemical environment. Moreover, it is higher by 20.4 eV (16 σ) than a prediction of the semi-empirical calculations by Larkins which indicates an influence of the "atomic structure effect" on absolute energies of the Auger transitions following the electron capture decay and, possibly, some imperfections in the calculations. Good agreement of the measured and predicted KL1L2(3P0/1P1) transition intensity ratios indicates perceptible influence of the relativistic effects on the KLL Auger spectrum even at Z = 28.

Dark matter in the Sun: scattering off electrons vs nucleons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garani, Raghuveer; Palomares-Ruiz, Sergio, E-mail: garani@th.physik.uni-bonn.de, E-mail: sergiopr@ific.uv.es

The annihilation of dark matter (DM) particles accumulated in the Sun could produce a flux of neutrinos, which is potentially detectable with neutrino detectors/telescopes and the DM elastic scattering cross section can be constrained. Although the process of DM capture in astrophysical objects like the Sun is commonly assumed to be due to interactions only with nucleons, there are scenarios in which tree-level DM couplings to quarks are absent, and even if loop-induced interactions with nucleons are allowed, scatterings off electrons could be the dominant capture mechanism. We consider this possibility and study in detail all the ingredients necessary tomore » compute the neutrino production rates from DM annihilations in the Sun (capture, annihilation and evaporation rates) for velocity-independent and isotropic, velocity-dependent and isotropic and momentum-dependent scattering cross sections for DM interactions with electrons and compare them with the results obtained for the case of interactions with nucleons. Moreover, we improve the usual calculations in a number of ways and provide analytical expressions in three appendices. Interestingly, we find that the evaporation mass in the case of interactions with electrons could be below the GeV range, depending on the high-velocity tail of the DM distribution in the Sun, which would open a new mass window for searching for this type of scenarios.« less

Electron-electron interaction in ion-atom collisions studied by projectile state-resolved Auger-electron spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dohyung Lee.

This dissertation addresses the problem of dynamic electron-electron interactions in fast ion-atom collisions using projectile Auger electron spectroscopy. The study was carried out by measuring high-resolution projectile KKL Auger electron spectra as a function of projectile energy for the various collision systems of 0.25-2 MeV/u O{sup q+} and F{sup q+} incident on H{sub 2} and He targets. The electrons were detected in the beam direction, where the kinematic broadening is minimized. A zero-degree tandem electron spectrometer system, was developed and showed the versatility of zero-degree measurements of collisionally-produced atomic states. The zero-degree binary encounter electrons (BEe), quasifree target electrons ionizedmore » by the projectiles in head-on collisions, were observed as a strong background in the KLL Auger electron spectrum. They were studied by treating the target ionization as 180{degree} Rutherford elastic scattering in the projectile frame, and resulted in a validity test of the impulse approximation (IA) and a way to determine the spectrometer efficiency. An anomalous q-dependence, in which the zero-degree BEe yields increase with decreasing projectile charge state (q), was observed. State-resolved KLL Auger cross sections were determined by using the BEe normalization and thus the cross section of the electron-electron interactions such as resonant transfer-excitation (RTE), electron-electron excitation (eeE), and electron-electron ionization (eeI) were determined. Projectile 2l capture with 1s {yields} 2p excitation by the captured target electron was observed as an RTE process with Li-like and He-like projectiles and the measured RTEA (RTE followed by Auger decay) cross sections showed good agreement with an RTE-IA treatment and RTE alignment theory.« less

Electron-capture Rates for pf-shell Nuclei in Stellar Environments and Nucleosynthesis

NASA Astrophysics Data System (ADS)

Suzuki, Toshio; Honma, Michio; Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Hidakai, Jun; Otsuka, Takaharu

Gamow-Teller strengths in pf-shell nuclei obtained by a new shell-model Hamltonian, GXPF1J, are used to evaluate electron-capture rates in pf-shell nuclei at stellar environments. The nuclear weak rates with GXPF1J, which are generally smaller than previous evaluations for proton-rich nuclei, are applied to nucleosynthesis in type Ia supernova explosions. The updated rates are found to lead to less production of neutron-rich nuclei such as 58Ni and 54Cr, thus toward a solution of the problem of over-production of neutron-rich isotopes of iron-group nuclei compared to the solar abundance.

Identification of Abscisic Acid in Tulipa gesneriana L. by Gas-Liquid Chromatography with Electron Capture and Combined Gas-Liquid Chromatography and Mass Spectrometry

PubMed Central

Terry, Paul H.; Aung, Louis H.; De Hertogh, August A.

1982-01-01

A major growth inhibitory substance of tulip bulbs (Tulipa gesneriana L. cv Paul Richter) has been unequivocally shown to be abscisic acid (ABA). The ABA methyl ester of the free ether-soluble acid fractions of tulip organs had the identical retention time on gas-liquid chromatography with electron capture detector as authentic ABA methyl ester. In addition, the mass spectra were the same. On a unit dry matter basis, the basalplate and floral shoot contained 3.6 and 2.6 times more ABA than the fleshy scales, respectively. PMID:16662721

Differential cross sections for electron capture in p + H2 collisions

NASA Astrophysics Data System (ADS)

Igarashi, Akinori; Gulyás, Laszlo; Ohsaki, Akihiko

2017-11-01

Projectile angular distributions for electron capture in p + H2 collisions at 25 and 75 keV impact energies, measured by Sharma et al. [Phys. Rev. A 86, 022706 (2012)], are calculated using the CDW-EIS and eikonal approximations. Angular distributions evaluated in the CDW-EIS approximation are in good agreement with the experimental data measured for coherent projectile beams. Incoherent projectile scatterings are also considered by folding the coherent angular distributions over the transverse momentum distribution of the projectile wave-packet. Reasonable agreements with the measurements are obtained only with coherence parameters very different from those reported in the experiments.

Pentafluorobenzyl bromide-A versatile derivatization agent in chromatography and mass spectrometry: I. Analysis of inorganic anions and organophosphates.

PubMed

Tsikas, Dimitrios

2017-02-01

Pentafluorobenzyl bromide (PFB-Br) is a versatile derivatization agent. It is widely used in chromatography and mass spectrometry since several decades. The bromide atom is largely the single leaving group of PFB-Br. It is substituted by wide a spectrum of nucleophiles in aqueous and non-aqueous systems to form electrically neutral, in most organic solvents soluble, generally thermally stable, volatile, strongly electron-capturing and ultraviolet light-absorbing derivatives. Because of these greatly favoured physicochemical properties, PFB-Br emerged an ideal derivatization agent for highly sensitive analysis of endogenous and exogenous substances including various inorganic and organic anions by electron capture detection or after electron-capture negative-ion chemical ionization in GC-MS. The present article attempts an appraisal of the utility of PFB-Br in analytical chemistry. It reviews and discusses papers dealing with the use of PFB-Br as the derivatization reagent in the qualitative and quantitative analysis of endogenous and exogenous inorganic anions in various biological samples, notably plasma, urine and saliva. These analytes include nitrite, nitrate, cyanide and dialkyl organophosphates. Special emphasis is given to mass spectrometry-based approaches and stable-isotope dilution techniques. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultralow energy calibration of LUX detector using Xe 127 electron capture

DOE PAGES

Akerib, D. S.; Alsum, S.; Araújo, H. M.; ...

2017-12-01

We report an absolute calibration of the ionization yields(more » $$\\textit{Q$$_y$})$ and fluctuations for electronic recoil events in liquid xenon at discrete energies between 186 eV and 33.2 keV. The average electric field applied across the liquid xenon target is 180 V/cm. The data are obtained using low energy $$^{127}$$Xe electron capture decay events from the 95.0-day first run from LUX (WS2013) in search of Weakly Interacting Massive Particles (WIMPs). The sequence of gamma-ray and X-ray cascades associated with $$^{127}$$I de-excitations produces clearly identified 2-vertex events in the LUX detector. We observe the K- (binding energy, 33.2 keV), L- (5.2 keV), M- (1.1 keV), and N- (186 eV) shell cascade events and verify that the relative ratio of observed events for each shell agrees with calculations. The N-shell cascade analysis includes single extracted electron (SE) events and represents the lowest-energy electronic recoil $$\\textit{in situ}$$ measurements that have been explored in liquid xenon.« less

Ultralow energy calibration of LUX detector using Xe 127 electron capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akerib, D. S.; Alsum, S.; Araújo, H. M.

We report an absolute calibration of the ionization yields (Q y) and fluctuations for electronic recoil events in liquid xenon at discrete energies between 186 eV and 33.2 keV. The average electric field applied across the liquid xenon target is 180 V/cm. The data are obtained using low energy 127Xe electron capture decay events from the 95.0-day first run from LUX (WS2013) in search of weakly interacting massive particles. The sequence of gamma-ray and x-ray cascades associated with 127I deexcitations produces clearly identified two-vertex events in the LUX detector. We observe the K-(binding energy, 33.2 keV), L-(5.2 keV), M-(1.1 keV),more » and N-(186 eV) shell cascade events and verify that the relative ratio of observed events for each shell agrees with calculations. In conclusion, the N-shell cascade analysis includes single extracted electron (SE) events and represents the lowest-energy electronic recoil in situ measurements that have been explored in liquid xenon.« less

Ultralow energy calibration of LUX detector using Xe 127 electron capture

NASA Astrophysics Data System (ADS)

Akerib, D. S.; Alsum, S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Biesiadzinski, T. P.; Boulton, E. M.; Brás, P.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Currie, A.; Cutter, J. E.; Davison, T. J. R.; Dobi, A.; Druszkiewicz, E.; Edwards, B. N.; Fallon, S. R.; Fan, A.; Fiorucci, S.; Gaitskell, R. J.; Genovesi, J.; Ghag, C.; Gilchriese, M. G. D.; Hall, C. R.; Hanhardt, M.; Haselschwardt, S. J.; Hertel, S. A.; Hogan, D. P.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Jacobsen, R. G.; Ji, W.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Knoche, R.; Larsen, N. A.; Lenardo, B. G.; Lesko, K. T.; Lindote, A.; Lopes, M. I.; Manalaysay, A.; Mannino, R. L.; Marzioni, M. F.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morad, J. A.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; O'Sullivan, K.; Oliver-Mallory, K. C.; Palladino, K. J.; Pease, E. K.; Rhyne, C.; Shaw, S.; Shutt, T. A.; Silva, C.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Sumner, T. J.; Szydagis, M.; Taylor, D. J.; Taylor, W. C.; Tennyson, B. P.; Terman, P. A.; Tiedt, D. R.; To, W. H.; Tripathi, M.; Tvrznikova, L.; Uvarov, S.; Velan, V.; Verbus, J. R.; Webb, R. C.; White, J. T.; Whitis, T. J.; Witherell, M. S.; Wolfs, F. L. H.; Xu, J.; Yazdani, K.; Young, S. K.; Zhang, C.

2017-12-01

We report an absolute calibration of the ionization yields (Qy ) and fluctuations for electronic recoil events in liquid xenon at discrete energies between 186 eV and 33.2 keV. The average electric field applied across the liquid xenon target is 180 V /cm . The data are obtained using low energy Xe 127 electron capture decay events from the 95.0-day first run from LUX (WS2013) in search of weakly interacting massive particles. The sequence of gamma-ray and x-ray cascades associated with I 127 deexcitations produces clearly identified two-vertex events in the LUX detector. We observe the K-(binding energy, 33.2 keV), L-(5.2 keV), M-(1.1 keV), and N-(186 eV) shell cascade events and verify that the relative ratio of observed events for each shell agrees with calculations. The N-shell cascade analysis includes single extracted electron (SE) events and represents the lowest-energy electronic recoil in situ measurements that have been explored in liquid xenon.

Ultralow energy calibration of LUX detector using Xe 127 electron capture

DOE PAGES

Akerib, D. S.; Alsum, S.; Araújo, H. M.; ...

2017-12-28

We report an absolute calibration of the ionization yields (Q y) and fluctuations for electronic recoil events in liquid xenon at discrete energies between 186 eV and 33.2 keV. The average electric field applied across the liquid xenon target is 180 V/cm. The data are obtained using low energy 127Xe electron capture decay events from the 95.0-day first run from LUX (WS2013) in search of weakly interacting massive particles. The sequence of gamma-ray and x-ray cascades associated with 127I deexcitations produces clearly identified two-vertex events in the LUX detector. We observe the K-(binding energy, 33.2 keV), L-(5.2 keV), M-(1.1 keV),more » and N-(186 eV) shell cascade events and verify that the relative ratio of observed events for each shell agrees with calculations. In conclusion, the N-shell cascade analysis includes single extracted electron (SE) events and represents the lowest-energy electronic recoil in situ measurements that have been explored in liquid xenon.« less

Radiance line ratios Ly-β/Ly-α, Ly-γ/Ly-α, Ly-δ/Ly-α, and Ly-ε/Ly-α for soft X-ray emissions following charge exchange between C 6+ and Kr

DOE Office of Scientific and Technical Information (OSTI.GOV)

V. M. Andrianarijaona; Wulf, D.; McCammon, D.

2015-02-04

The radiance line ratios Ly-β/Ly-α, Ly-γ/Ly-α, Ly-δ/Ly-α, and Ly-ε/Ly-α for soft X-ray emission following charge exchange (CX) between C 6+ and Kr are reported in this paper for collision energies between approximately 320 and 46,000 eV/u. The corresponding collision velocities (250–3000 km/s) are characteristic of the solar wind. X-ray spectra were obtained at the Oak Ridge National Laboratory Multicharged Ion Research Facility using a microcalorimeter X-ray detector with a resolution on the order of 10 eV FWHM. The measured Ly-ε/Ly-α is zero for all considered energies and suggests that very little, if any, capture to 6p occurs. The measured Ly-β/Ly-αmore » and Ly-γ/Ly-α ratios intersect and form a well resolved node around (950 ± 50) km/s, which could be used as an astrophysical velocity indicative tool. The results reported here are compared to calculations for C 6+ + H since no published theory for C 6+ + Kr is known to exist. Finally, double-electron-capture (DEC) and other multi-electron processes are possible. True double capture is estimated to be only 10% of the single-electron-capture (SEC).« less

Mechanism of 'GSI oscillations' in electron capture by highly charged hydrogen-like atomic ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krainov, V. P., E-mail: vpkrainov@mail.ru

2012-07-15

We suggest a qualitative explanation of oscillations in electron capture decays of hydrogen-like {sup 140}Pr and {sup 142}Pm ions observed recently in an ion experimental storage ring (ESR) of Gesellschaft fuer Schwerionenforschung (GSI) mbH, Darmstadt, Germany. This explanation is based on the electron multiphoton Rabi oscillations between two Zeeman states of the hyperfine ground level with the total angular momentum F = 1/2. The Zeeman splitting is produced by a constant magnetic field in the ESR. Transitions between these states are produced by the second, sufficiently strong alternating magnetic field that approximates realistic fields in the GSI ESR. The Zeemanmore » splitting amounts to only about 10{sup -5} eV. This allows explaining the observed quantum beats with the period 7 s.« less

Chemical Consequences of Radioactive Decay and their Biological Implications.

PubMed

DeJesus, Onofre T

2017-11-10

The chemical effects of radioactive decay arise from (1) transmutation, (2) formation of charged daughter nuclei, (3) recoil of the daughter nuclei, (4) electron "shakeoff" phenomenon and (5) vacancy cascade in decays via electron capture and internal conversion. This review aims to reiterate what has been known for a long time regarding the chemical consequences of radioactive decay and gives a historical perspective to the observations that led to their elucidation. The energetics of the recoil process in each decay mode is discussed in relation to the chemical bond between the decaying nucleus and the parent molecule. Special attention is given to the biological effects of the Auger process following decay by electron capture and internal conversion because of their possible utility in internal radiotherapy. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Capturing structured, pulmonary disease-specific data elements in electronic health records.

PubMed

Gronkiewicz, Cynthia; Diamond, Edward J; French, Kim D; Christodouleas, John; Gabriel, Peter E

2015-04-01

Electronic health records (EHRs) have the potential to improve health-care quality by allowing providers to make better decisions at the point of care based on electronically aggregated data and by facilitating clinical research. These goals are easier to achieve when key, disease-specific clinical information is documented as structured data elements (SDEs) that computers can understand and process, rather than as free-text/natural-language narrative. This article reviews the benefits of capturing disease-specific SDEs. It highlights several design and implementation considerations, including the impact on efficiency and expressivity of clinical documentation and the importance of adhering to data standards when available. Pulmonary disease-specific examples of collection instruments are provided from two commonly used commercial EHRs. Future developments that can leverage SDEs to improve clinical quality and research are discussed.

Use of large electronic health record databases for environmental epidemiology studies.

EPA Science Inventory

Background: Electronic health records (EHRs) are a ubiquitous component of the United States healthcare system and capture nearly all data collected in a clinic or hospital setting. EHR databases are attractive for secondary data analysis as they may contain detailed clinical rec...

75 FR 62149 - Records Schedules; Availability and Request for Comments

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-07

... publications through the editorial process and capture bibliographic information for printed publications. 7... electronic data relating to persons of interest when the data relates to unique and significant intelligence... records of an electronic information system used to access intelligence and investigative data. 22...

Plasmon tsunamis on metallic nanoclusters.

PubMed

Lucas, A A; Sunjic, M

2012-03-14

A model is constructed to describe inelastic scattering events accompanying electron capture by a highly charged ion flying by a metallic nanosphere. The electronic energy liberated by an electron leaving the Fermi level of the metal and dropping into a deep Rydberg state of the ion is used to increase the ion kinetic energy and, simultaneously, to excite multiple surface plasmons around the positively charged hole left behind on the metal sphere. This tsunami-like phenomenon manifests itself as periodic oscillations in the kinetic energy gain spectrum of the ion. The theory developed here extends our previous treatment (Lucas et al 2011 New J. Phys. 13 013034) of the Ar(q+)/C(60) charge exchange system. We provide an analysis of how the individual multipolar surface plasmons of the metallic sphere contribute to the formation of the oscillatory gain spectrum. Gain spectra showing characteristic, tsunami-like oscillations are simulated for Ar(15+) ions capturing one electron in distant collisions with Al and Na nanoclusters.

Evaluating the accuracy of recent electron transport models at predicting Hall thruster plasma dynamics

NASA Astrophysics Data System (ADS)

Cappelli, Mark; Young, Christopher

2016-10-01

We present continued efforts towards introducing physical models for cross-magnetic field electron transport into Hall thruster discharge simulations. In particular, we seek to evaluate whether such models accurately capture ion dynamics, both averaged and resolved in time, through comparisons with measured ion velocity distributions which are now becoming available for several devices. Here, we describe a turbulent electron transport model that is integrated into 2-D hybrid fluid/PIC simulations of a 72 mm diameter laboratory thruster operating at 400 W. We also compare this model's predictions with one recently proposed by Lafluer et al.. Introducing these models into 2-D hybrid simulations is relatively straightforward and leverages the existing framework for solving the electron fluid equations. The models are tested for their ability to capture the time-averaged experimental discharge current and its fluctuations due to ionization instabilities. Model predictions are also more rigorously evaluated against recent laser-induced fluorescence measurements of time-resolved ion velocity distributions.

Electron capture activation of the disulfide bond. The role of the asymmetry and electronegativity.

PubMed

Gámez, José A; Serrano-Andrés, Luis; Yáñez, Manuel

2010-02-07

The effects of electron capture on the structure of XSSX' disulfide derivatives in which the substituents attached to the sulfur atoms have different electronegativites have been investigated at different levels of theory, namely DFT, MP2, QCISD and CASSCF/CASPT2. Although it has been generally assumed that electron attachment to disulfide derivatives leads to a systematic and significant activation of the S-S bond, our results show that this is the case only when the substituents X or X' have low electronegativity. Otherwise, the S-S bond in the anion remains practically unperturbed and only the S-X bond is largely activated or even broken, because the extra electron occupies the sigma*(S-X) rather than the sigma*(S-S) antibonding orbital. Our results also show that S-S activation yields a system with a unique anion, whereas when the S-X activation is significant, two stable anionic species, stretched and bent, are formed.

Case Report Form Reporter: A Key Component for the Integration of Electronic Medical Records and the Electronic Data Capture System.

PubMed

Matsumura, Yasushi; Hattori, Atsushi; Manabe, Shiro; Takahashi, Daiyo; Yamamoto, Yuichiro; Murata, Taizo; Nakagawa, Akito; Mihara, Naoki; Takeda, Toshihiro

2017-01-01

To improve the efficiency of clinical research, we developed a system to integrate electronic medical records (EMRs) and the electronic data capture system (EDC). EDC is divided into case report form (CRF) reporter and CDMS with CRF receiver with data communication using the operational data model (ODM). The CRF reporter is incorporated into the EMR to share data witth the EMR. In the data transcription type, doctors enter data using a progress note template, which are transmitted to the reporter template. It then generates the ODM. In the direct record type, reporter templates open from the progress note and generate narrative text to make record in the progress note. The configuration files for a study are delivered from the contents server to minimize the setup. This system has been used for 15 clinical studies including 3 clinical trials. This system can save labor and financial costs in clinical research.

Online, automatic, ionospheric maps: IRI-PLAS-MAP

NASA Astrophysics Data System (ADS)

Arikan, F.; Sezen, U.; Gulyaeva, T. L.; Cilibas, O.

2015-04-01

Global and regional behavior of the ionosphere is an important component of space weather. The peak height and critical frequency of ionospheric layer for the maximum ionization, namely, hmF2 and foF2, and the total number of electrons on a ray path, Total Electron Content (TEC), are the most investigated and monitored values of ionosphere in capturing and observing ionospheric variability. Typically ionospheric models such as International Reference Ionosphere (IRI) can provide electron density profile, critical parameters of ionospheric layers and Ionospheric electron content for a given location, date and time. Yet, IRI model is limited by only foF2 STORM option in reflecting the dynamics of ionospheric/plasmaspheric/geomagnetic storms. Global Ionospheric Maps (GIM) are provided by IGS analysis centers for global TEC distribution estimated from ground-based GPS stations that can capture the actual dynamics of ionosphere and plasmasphere, but this service is not available for other ionospheric observables. In this study, a unique and original space weather service is introduced as IRI-PLAS-MAP from http://www.ionolab.org

Resonant recombination and autoionization in electron-ion collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mueller, A.

1990-06-01

The occurence of resonances in elastic and inelastic electron-ion collisions is discussed. Resonant processes involve excitation of the ion with simultaneous capture of the initially free electron. The decay mechanism subsequent to the formation of the intermediate multiply excited state determines whether a resonance is found in recombination, excitation, elastic scattering, in single or even in multiple ionization. This review concentrates on resonances in the ionization channel. Correlated two-electron transitions are considered.

HST Solar Arrays photographed by Electronic Still Camera

NASA Technical Reports Server (NTRS)

1993-01-01

This medium close-up view of one of two original Solar Arrays (SA) on the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and downlinked to ground controllers soon afterward. This view shows the cell side of the minus V-2 panel. Electronic still photography is a technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality.

Algorithmic implementation of particle-particle ladder diagram approximation to study strongly-correlated metals and semiconductors

NASA Astrophysics Data System (ADS)

Prayogi, A.; Majidi, M. A.

2017-07-01

In condensed-matter physics, strongly-correlated systems refer to materials that exhibit variety of fascinating properties and ordered phases, depending on temperature, doping, and other factors. Such unique properties most notably arise due to strong electron-electron interactions, and in some cases due to interactions involving other quasiparticles as well. Electronic correlation effects are non-trivial that one may need a sufficiently accurate approximation technique with quite heavy computation, such as Quantum Monte-Carlo, in order to capture particular material properties arising from such effects. Meanwhile, less accurate techniques may come with lower numerical cost, but the ability to capture particular properties may highly depend on the choice of approximation. Among the many-body techniques derivable from Feynman diagrams, we aim to formulate algorithmic implementation of the Ladder Diagram approximation to capture the effects of electron-electron interactions. We wish to investigate how these correlation effects influence the temperature-dependent properties of strongly-correlated metals and semiconductors. As we are interested to study the temperature-dependent properties of the system, the Ladder diagram method needs to be applied in Matsubara frequency domain to obtain the self-consistent self-energy. However, at the end we would also need to compute the dynamical properties like density of states (DOS) and optical conductivity that are defined in the real frequency domain. For this purpose, we need to perform the analytic continuation procedure. At the end of this study, we will test the technique by observing the occurrence of metal-insulator transition in strongly-correlated metals, and renormalization of the band gap in strongly-correlated semiconductors.

Mechanistic Study on Electronic Excitation Dissociation of the Cellobiose-Na+ Complex

NASA Astrophysics Data System (ADS)

Huang, Yiqun; Pu, Yi; Yu, Xiang; Costello, Catherine E.; Lin, Cheng

2016-02-01

The recent development of electron activated dissociation (ExD) techniques has opened the door for high-throughput, detailed glycan structural elucidation. Among them, ExD methods employing higher-energy electrons offer several advantages over low-energy electron capture dissociation (ECD), owing to their applicability towards chromophore-labeled glycans and singly charged ions, and ability to provide more extensive structural information. However, a lack of understanding of these processes has hindered rational optimization of the experimental conditions for more efficient fragmentation as well as the development of informatics tools for interpretation of the complex glycan ExD spectra. Here, cellobiose-Na+ was used as the model system to investigate the fragmentation behavior of metal-adducted glycans under irradiation of electrons with energy exceeding their ionization potential, and served as the basis on which a novel electronic excitation dissociation (EED) mechanism was proposed. It was found that ionization of the glycan produces a mixture of radical cations and ring-opened distonic ions. These distonic ions then capture a low-energy electron to produce diradicals with trivial singlet-triplet splitting, and subsequently undergo radical-induced dissociation to produce a variety of fragment ions, the abundances of which are influenced by the stability of the distonic ions from which they originate.

Negative ions of polyatomic molecules.

PubMed Central

Christophorou, L G

1980-01-01

In this paper general concepts relating to, and recent advances in, the study of negative ions of polyatomic molecules area discussed with emphasis on halocarbons. The topics dealt with in the paper are as follows: basic electron attachment processes, modes of electron capture by molecules, short-lived transient negative ions, dissociative electron attachment to ground-state molecules and to "hot" molecules (effects of temperature on electron attachment), parent negative ions, effect of density, nature, and state of the medium on electron attachment, electron attachment to electronically excited molecules, the binding of attached electrons to molecules ("electron affinity"), and the basic and the applied significance of negative-ion studies. PMID:7428744

Overview of the High Performance Antiproton Trap (HiPAT) Experiment

NASA Technical Reports Server (NTRS)

Martin, James; Chakrabarti, Suman; Pearson, Boise; Sims, W. Herbert; Lewis, Raymond; Fant, Wallace; Rodgers, Stephen (Technical Monitor)

2002-01-01

A general overview of the High Performance Antiproton Trap (HiPAT) Experiment is presented. The topics include: 1) Why Antimatter? 2) HiPAT Applicability; 3) Approach-Goals; 4) HiPAT General Layout; 5) Sizing For Containment; 6) Laboratory Operations; 7) Vacuum System Cleaning; 8) Ion Production Via Electron Gun; 9) Particle Capture Via Ion Sources; 10) Ion Beam Steering/Focusing; 11) Ideal Ion Stacking Sequence; 12) Setup For Dynamic Capture; 13) Dynamic Capture of H(+) Ions; 14) Dynamic Capture; 15) Radio Frequency Particle Detection; 16) Radio Frequency Antenna Modeling; and 17) R.F. Stabilization-Low Frequencies. A short presentation of propulsion applications of Antimatter is also given. This paper is in viewgraph form.

Web-based recruitment and survey methodology to capture followers of popular diets: the adhering to dietary approaches for personal taste (ADAPT) feasibility survey

USDA-ARS?s Scientific Manuscript database

Background: Although there is interest in popular diets such as vegan/vegetarian, Paleo, and other whole food diets, existing cohort studies lack specific data for these subgroups. With the evolution of new technologies, such as electronic data capture and web-based surveys, their application to nut...

A Brief Introduction to Web-Based Note Capture

ERIC Educational Resources Information Center

Ovadia, Steven

2012-01-01

While physical notebooks and locally saved electronic files are certainly helpful, there are a number of web-based solutions that might be useful to someone conducting research online, or looking to hold their notes in a web-based environment. The main advantage of a web-based note capture tool is that one is able to access it from just about…

Instant replay.

PubMed

Rosenthal, David I

2013-06-01

With widespread adoption of electronic health records (EHRs) and electronic clinical documentation, health care organizations now have greater faculty to review clinical data and evaluate the efficacy of quality improvement efforts. Unfortunately, I believe there is a fundamental gap between actual health care delivery and what we document in the current EHR systems. This process of capturing the patient encounter, which I'll refer to as transcription, is prone to significant data loss due to inadequate methods of data capture, multiple points of view, and bias and subjectivity in the transcriptional process. Our current EHR, text-based clinical documentation systems are lossy abstractions - one sided accounts of what take place between patients and providers. Our clinical notes contain the breadcrumbs of relationships, conversations, physical exams, and procedures but often lack the ability to capture the form, the emotions, the images, the nonverbal communication, and the actual narrative of interactions between human beings. I believe that a video record, in conjunction with objective transcriptional services and other forms of data capture, may provide a closer approximation to the truth of health care delivery and may be a valuable tool for healthcare improvement. Copyright © 2013 Elsevier Inc. All rights reserved.

Direct Evidence of EMIC-Driven Electron Loss in Space: Evaluation of an Electron Dropout Event

NASA Astrophysics Data System (ADS)

Zhang, X.; Li, W.; Ma, Q.; Thorne, R. M.; Angelopoulos, V.

2015-12-01

Electromagnetic ion cyclotron (EMIC) waves have been proposed as a mechanism to cause efficient losses of highly relativistic (>MeV) electrons via gyroresonant interactions. However, simultaneous observations of EMIC waves and equatorial electron pitch angle distributions, which can be used to directly quantify the EMIC wave scattering effect, are still very limited. In the present study, we evaluate the effect of EMIC waves on the pitch angle scattering of relativistic and ultrarelativistic (0.5-5 MeV) electrons during the main phase of a geomagnetic storm, when intense EMIC wave activity was observed in situ (in the plasma plume region with high plasma density) on both the Van Allen Probes and one of the THEMIS probes. EMIC waves captured on the ground across the Canadian Array for Real-time Investigations of Magnetic Activity (CARISMA) and enhanced precipitation of >~0.7 MeV electrons captured by POES are used to infer the MLT coverage of EMIC waves. Based on the observed EMIC wave spectra, local fpe and fce, we estimate the wave diffusion rates and model the evolution of electron pitch angle distributions. By comparing the modeled results with local observations of pitch angle distributions, for the first time, we are able to show direct, quantitative evidence of EMIC wave-driven relativistic electron loss in the Earth's outer radiation belt.

Negative-ion formation in the explosives RDX, PETN, and TNT using the Reversal Electron Attachment Detection (READ) technique

NASA Technical Reports Server (NTRS)

Chutijian, Ara; Boumsellek, S.; Alajajian, S. H.

1992-01-01

In the search for high sensitivity and direct atmospheric sampling of trace species, techniques have been developed such as atmospheric-sampling, glow-discharge ionization (ASGDI), corona discharge, atmospheric pressure ionization (API), electron-capture detection (ECD), and negative-ion chemical ionization (NICI) that are capable of detecting parts-per-billion to parts-per-trillion concentrations of trace species. These techniques are based on positive- or negative-ion formation via charge-transfer to the target, or electron capture under multiple-collision conditions in a Maxwellian distribution of electron energies at the source temperature. One drawback of the high-pressure, corona- or glow-discharge devices is that they are susceptible to interferences either through indistinguishable product masses, or through undesired ion-molecule reactions. The ASGDI technique is relatively immune from such interferences, since at target concentrations of less than 1 ppm the majority of negative ions arises via electron capture rather than through ion-molecule chemistry. A drawback of the conventional ECD, and possibly of the ASGDI, is that they exhibit vanishingly small densities of electrons with energies in the range 0-10 millielectron volts (meV), as can be seen from a typical Maxwellian electron energy distribution function at T = 300 K. Slowing the electrons to these subthermal (less than 10 meV) energies is crucial, since the cross section for attachment of several large classes of molecules is known to increase to values larger than 10(exp -12) sq cm at near-zero electron energies. In the limit of zero energy these cross sections are predicted to diverge as epsilon(exp -1/2), where epsilon is the electron energy. In order to provide a better 'match' between the electron energy distribution function and attachment cross section, a new concept of attachment in an electrostatic mirror was developed. In this scheme, electrons are brought to a momentary halt by reversing their direction with electrostatic fields. At this turning point the electrons have zero or near-zero energy. A beam of target molecules is introduced, and the resultant negative ions extracted. This basic idea has been recently improved to allow for better reversal geometry, higher electron currents, lower backgrounds, and increased negative-ion extraction efficiency. We present herein application of the so-called reversal electron attachment detector (READ) to the study of negative-ion formation in the explosives molecules RDX, PETN, and TNT under single-collision conditions.

Circular dichroism in photo-single-ionization of unoriented atoms.

PubMed

Feagin, James M

2002-01-28

We predict circular dichroism in photo-single-ionization angular distributions from spherically symmetric atomic states if the ionized electron is detected using two-slit interferometry. We demonstrate that the resulting electron interference pattern captures phase information on quadrupole corrections to the photoionization amplitude lost in conventional angular distributions.

78 FR 11877 - Announcement of Requirements Gathering Meetings for the Electronic Manifest (e-Manifest) System

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-20

... Gathering Meetings for the Electronic Manifest (e-Manifest) System AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of public meetings. SUMMARY: EPA's Office of Resource Conservation and Recovery...'') system to capture information regarding the shipment of hazardous waste from the time it leaves the...

17 CFR 38.552 - Elements of an acceptable audit trail program.

Code of Federal Regulations, 2014 CFR

2014-04-01

... of the order shall also be captured. (b) Transaction history database. A designated contract market's audit trail program must include an electronic transaction history database. An adequate transaction history database includes a history of all trades executed via open outcry or via entry into an electronic...

17 CFR 38.552 - Elements of an acceptable audit trail program.

Code of Federal Regulations, 2013 CFR

2013-04-01

... of the order shall also be captured. (b) Transaction history database. A designated contract market's audit trail program must include an electronic transaction history database. An adequate transaction history database includes a history of all trades executed via open outcry or via entry into an electronic...

Semiclassical analysis of angular differential cross sections for single-electron capture in 250-eV H++H collisions

NASA Astrophysics Data System (ADS)

Frémont, F.

2015-05-01

A classical model based on the resolution of Hamilton equations of motion is used to determine the angular distribution of H projectiles following single-electron capture in H++H collisions at an incident projectile energy of 250 eV. At such low energies, the experimental charge-exchange probability and angular differential cross sections exhibit oscillatory structures that are classically related to the number of swaps the electron experiences between the target and the projectile during the collision. These oscillations are well reproduced by models based on quantum mechanics. In the present paper, the angular distribution of H projectiles is determined classically, at angles varying from 0.1° up to 7°. The variation in intensity due to interferences caused by the indiscernibility between different trajectories is calculated, and the role of these interferences is discussed.

Charge-equilibrium and radiation of low-energy cosmic rays passing through interstellar medium

NASA Technical Reports Server (NTRS)

Rule, D. W.; Omidvar, K.

1977-01-01

The charge equilibrium and radiation of an oxygen and an iron beam in the MeV per nucleon energy range, representing a typical beam of low-energy cosmic rays passing through the interstellar medium, is considered. Electron loss of the beam has been taken into account by means of the First Born approximation allowing for the target atom to remain unexcited, or to be excited to all possible states. Electron capture cross sections have been calculated by means of the scaled Oppenheimer-Brinkman-Kramers approximation, taking into account all atomic shells of the target atoms. Radiation of the beam due to electron capture into the excited states of the ion, collisional excitation and collisional inner-shell ionization of the ions has been considered. Effective X-ray production cross sections and multiplicities for the most energetic X-ray lines emitted by the Fe and O beams have been calculated.

Automated Transformation of CDISC ODM to OpenClinica.

PubMed

Gessner, Sophia; Storck, Michael; Hegselmann, Stefan; Dugas, Martin; Soto-Rey, Iñaki

2017-01-01

Due to the increasing use of electronic data capture systems for clinical research, the interest in saving resources by automatically generating and reusing case report forms in clinical studies is growing. OpenClinica, an open-source electronic data capture system enables the reuse of metadata in its own Excel import template, hampering the reuse of metadata defined in other standard formats. One of these standard formats is the Operational Data Model for metadata, administrative and clinical data in clinical studies. This work suggests a mapping from Operational Data Model to OpenClinica and describes the implementation of a converter to automatically generate OpenClinica conform case report forms based upon metadata in the Operational Data Model.

Application of PIXE in the determination of the production cross section of a radionuclide decaying by electron capture

NASA Astrophysics Data System (ADS)

Morales, J. R.; Chesta, M. A.; Cancino, S. A.; Miranda, P. A.; Dinator, M. I.; Avila, M. J.

2005-01-01

Proton induced X-ray emission (PIXE) has been applied to the measurement of the production cross section of a radionuclide decaying by electron capture. By performing a PIXE type experiment on the daughter nuclide important advantages are obtained. The determination of some factors with usually large uncertainties, like solid angle and detector efficiency were avoided. The method was applied to the determination of cross section of the reaction 63Cu(d, p)64Cu at 2.4 MeV for 64Cu production. This result is in full agreement with that obtained through the decay of the 1346 keV gamma ray of 64Cu.

The use of Research Electronic Data Capture (REDCap) software to create a database of librarian-mediated literature searches.

PubMed

Lyon, Jennifer A; Garcia-Milian, Rolando; Norton, Hannah F; Tennant, Michele R

2014-01-01

Expert-mediated literature searching, a keystone service in biomedical librarianship, would benefit significantly from regular methodical review. This article describes the novel use of Research Electronic Data Capture (REDCap) software to create a database of literature searches conducted at a large academic health sciences library. An archive of paper search requests was entered into REDCap, and librarians now prospectively enter records for current searches. Having search data readily available allows librarians to reuse search strategies and track their workload. In aggregate, this data can help guide practice and determine priorities by identifying users' needs, tracking librarian effort, and focusing librarians' continuing education.

The feasibility of using 'bring your own device' (BYOD) technology for electronic data capture in multicentre medical audit and research.

PubMed

Faulds, M C; Bauchmuller, K; Miller, D; Rosser, J H; Shuker, K; Wrench, I; Wilson, P; Mills, G H

2016-01-01

Large-scale audit and research projects demand robust, efficient systems for accurate data collection, handling and analysis. We utilised a multiplatform 'bring your own device' (BYOD) electronic data collection app to capture observational audit data on theatre efficiency across seven hospital Trusts in South Yorkshire in June-August 2013. None of the participating hospitals had a dedicated information governance policy for bring your own device. Data were collected by 17 investigators for 392 individual theatre lists, capturing 14,148 individual data points, 12, 852 (91%) of which were transmitted to a central database on the day of collection without any loss of data. BYOD technology enabled accurate collection of a large volume of secure data across multiple NHS organisations over a short period of time. Bring your own device technology provides a method for collecting real-time audit, research and quality improvement data within healthcare systems without compromising patient data protection. © 2015 The Association of Anaesthetists of Great Britain and Ireland.

A photonic crystal hydrogel suspension array for the capture of blood cells from whole blood

NASA Astrophysics Data System (ADS)

Zhang, Bin; Cai, Yunlang; Shang, Luoran; Wang, Huan; Cheng, Yao; Rong, Fei; Gu, Zhongze; Zhao, Yuanjin

2016-02-01

Diagnosing hematological disorders based on the separation and detection of cells in the patient's blood is a significant challenge. We have developed a novel barcode particle-based suspension array that can simultaneously capture and detect multiple types of blood cells. The barcode particles are polyacrylamide (PAAm) hydrogel inverse opal microcarriers with characteristic reflection peak codes that remain stable during cell capture on their surfaces. The hydrophilic PAAm hydrogel scaffolds of the barcode particles can entrap various plasma proteins to capture different cells in the blood, with little damage to captured cells.Diagnosing hematological disorders based on the separation and detection of cells in the patient's blood is a significant challenge. We have developed a novel barcode particle-based suspension array that can simultaneously capture and detect multiple types of blood cells. The barcode particles are polyacrylamide (PAAm) hydrogel inverse opal microcarriers with characteristic reflection peak codes that remain stable during cell capture on their surfaces. The hydrophilic PAAm hydrogel scaffolds of the barcode particles can entrap various plasma proteins to capture different cells in the blood, with little damage to captured cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06368j

A multiplexed electronic architecture for opto-electronic patch sensor to effectively monitor heart rate and oxygen saturation

NASA Astrophysics Data System (ADS)

Yan, Liangwen; Hu, Sijung; Alharbi, Samah; Blanos, Panagiotis

2018-02-01

To effectively capture human vital signs, a multi-wavelength optoelectronic patch sensor (MOEPS), together with a schematic architecture of electronics, was developed to overcome the drawbacks of present photoplethysmographic (PPG) sensors. To obtain a better performance of in vivo physiological measurement, the optimal illuminations, i.e., light emitting diodes (LEDs) in the MOEPS, whose wavelength is automatically adjusted to each specific subject, were selected to capture better PPG signals. A multiplexed electronic architecture has been well established to properly drive the MOEPS and effectively capture pulsatile waveforms at rest. The protocol was designed to investigate its performance with the participation of 11 healthy subjects aged between 18 and 30. The signals obtained from green (525nm) and orange (595nm) illuminations were used to extract heart rate (HR) and oxygen saturation (SpO2%). These results were compared with data, simultaneously acquired, from a commercial ECG and a pulse oximeter. Considering the difficulty for current devices to attain the SpO2%, a new computing method, to obtain the value of SpO2%, is proposed depended on the green and orange wavelength illuminations. The values of SpO2% between the MOEPS and the commercial Pulse Oximeter devics showed that the results were in good agreement. The values of HR showed close correlation between commercial devices and the MOEPS (HR: r1=0.994(Green); r2=0.992(Orange); r3=0.975(Red); r4=0.990(IR)).

Breaking Symmetry in Time-Dependent Electronic Structure Theory to Describe Spectroscopic Properties of Non-Collinear and Chiral Molecules

NASA Astrophysics Data System (ADS)

Goings, Joshua James

Time-dependent electronic structure theory has the power to predict and probe the ways electron dynamics leads to useful phenomena and spectroscopic data. Here we report several advances and extensions of broken-symmetry time-dependent electronic structure theory in order to capture the flexibility required to describe non-equilibrium spin dynamics, as well as electron dynamics for chiroptical properties and vibrational effects. In the first half, we begin by discussing the generalization of self-consistent field methods to the so-called two-component structure in order to capture non-collinear spin states. This means that individual electrons are allowed to take a superposition of spin-1/2 projection states, instead of being constrained to either spin-up or spin-down. The system is no longer a spin eigenfunction, and is known a a spin-symmetry broken wave function. This flexibility to break spin symmetry may lead to variational instabilities in the approximate wave function, and we discuss how these may be overcome. With a stable non-collinear wave function in hand, we then discuss how to obtain electronic excited states from the non-collinear reference, along with associated challenges in their physical interpretation. Finally, we extend the two-component methods to relativistic Hamiltonians, which is the proper setting for describing spin-orbit driven phenomena. We describe the first implementation of the explicit time propagation of relativistic two-component methods and how this may be used to capture spin-forbidden states in electronic absorption spectra. In the second half, we describe the extension of explicitly time-propagated wave functions to the simulation of chiroptical properties, namely circular dichroism (CD) spectra of chiral molecules. Natural circular dichroism, that is, CD in the absence of magnetic fields, originates in the broken parity symmetry of chiral molecules. This proves to be an efficient method for computing circular dichroism spectra for high density-of-states chiral molecules. Next, we explore the impact of allowing nuclear motion on electronic absorption spectra within the context of mixed quantum-classical dynamics. We show that nuclear motion modulates the electronic response, and this gives rise to infrared absorption as well as Raman scattering phenomena in the computed dynamic polarizability. Finally, we explore the accuracy of several perturbative approximations to the equation-of-motion coupled-cluster methods for the efficient and accurate prediction of electronic absorption spectra.

A novel electron gun for inline MRI-linac configurations.

PubMed

Constantin, Dragoş E; Holloway, Lois; Keall, Paul J; Fahrig, Rebecca

2014-02-01

This work introduces a new electron gun geometry capable of robust functioning in the presence of a high strength external magnetic field for axisymmetric magnetic resonance imaging (MRI)-linac configurations. This allows an inline MRI-linac to operate without the need to isolate the linear accelerator (linac) using a magnetic shield. This MRI-linac integration approach not only leaves the magnet homogeneity unchanged but also provides the linac flexibility to move along the magnet axis of symmetry if the source to target distance needs to be adjusted. Simple electron gun geometry modifications of a Varian 600 C electron gun are considered and solved in the presence of an external magnetic field in order to determine a set of design principles for the new geometry. Based on these results, a new gun geometry is proposed and optimized in the fringe field of a 0.5 T open bore MRI magnet (GE Signa SP). A computer model for the 6 MeV Varian 600 C linac is used to determine the capture efficiency of the new electron gun-linac system in the presence of the fringe field of the same MRI scanner. The behavior of the new electron gun plus the linac system is also studied in the fringe fields of two other magnets, a 1.0 T prototype open bore magnet and a 1.5 T GE Conquest scanner. Simple geometrical modifications of the original electron gun geometry do not provide feasible solutions. However, these tests show that a smaller transverse cathode diameter with a flat surface and a slightly larger anode diameter could alleviate the current loss due to beam interactions with the anode in the presence of magnetic fields. Based on these findings, an initial geometry resembling a parallel plate capacitor with a hole in the anode is proposed. The optimization procedure finds a cathode-anode distance of 5 mm, a focusing electrode angle of 5°, and an anode drift tube length of 17.1 mm. Also, the linac can be displaced with ± 15 cm along the axis of the 0.5 T magnet without capture efficiency reduction below the experimental value in zero field. In this range of linac displacements, the electron beam generated by the new gun geometry is more effectively injected into the linac in the presence of an external magnetic field, resulting in approximately 20% increase of the target current compared to the original gun geometry behavior at zero field. The new gun geometry can generate and accelerate electron beams in external magnetic fields without current loss for fields higher than 0.11 T. The new electron-gun geometry is robust enough to function in the fringe fields of the other two magnets with a target current loss of no more than 16% with respect to the current obtained with no external magnetic fields. In this work, a specially designed electron gun was presented which can operate in the presence of axisymmetric strong magnetic fringe fields of MRI magnets. Computer simulations show that the electron gun can produce high quality beams which can be injected into a straight through linac such as Varian 600 C and accelerated with more efficiency in the presence of the external magnetic fields. Also, the new configuration allows linac displacements along the magnet axis in a range equal to the diameter of the imaging spherical volume of the magnet under consideration. The new electron gun-linac system can function in the fringe field of a MRI magnet if the field strength at the cathode position is higher than 0.11 T. The capture efficiency of the linac depends on the magnetic field strength and the field gradient. The higher the gradient the better the capture efficiency. The capture efficiency does not degrade more than 16%.

A novel electron gun for inline MRI-linac configurations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Constantin, Dragoş E., E-mail: dragos.constantin@varian.com; Fahrig, Rebecca; Holloway, Lois

2014-02-15

Purpose: This work introduces a new electron gun geometry capable of robust functioning in the presence of a high strength external magnetic field for axisymmetric magnetic resonance imaging (MRI)-linac configurations. This allows an inline MRI-linac to operate without the need to isolate the linear accelerator (linac) using a magnetic shield. This MRI-linac integration approach not only leaves the magnet homogeneity unchanged but also provides the linac flexibility to move along the magnet axis of symmetry if the source to target distance needs to be adjusted. Methods: Simple electron gun geometry modifications of a Varian 600C electron gun are considered andmore » solved in the presence of an external magnetic field in order to determine a set of design principles for the new geometry. Based on these results, a new gun geometry is proposed and optimized in the fringe field of a 0.5 T open bore MRI magnet (GE Signa SP). A computer model for the 6 MeV Varian 600C linac is used to determine the capture efficiency of the new electron gun-linac system in the presence of the fringe field of the same MRI scanner. The behavior of the new electron gun plus the linac system is also studied in the fringe fields of two other magnets, a 1.0 T prototype open bore magnet and a 1.5 T GE Conquest scanner. Results: Simple geometrical modifications of the original electron gun geometry do not provide feasible solutions. However, these tests show that a smaller transverse cathode diameter with a flat surface and a slightly larger anode diameter could alleviate the current loss due to beam interactions with the anode in the presence of magnetic fields. Based on these findings, an initial geometry resembling a parallel plate capacitor with a hole in the anode is proposed. The optimization procedure finds a cathode-anode distance of 5 mm, a focusing electrode angle of 5°, and an anode drift tube length of 17.1 mm. Also, the linac can be displaced with ±15 cm along the axis of the 0.5 T magnet without capture efficiency reduction below the experimental value in zero field. In this range of linac displacements, the electron beam generated by the new gun geometry is more effectively injected into the linac in the presence of an external magnetic field, resulting in approximately 20% increase of the target current compared to the original gun geometry behavior at zero field. The new gun geometry can generate and accelerate electron beams in external magnetic fields without current loss for fields higher than 0.11 T. The new electron-gun geometry is robust enough to function in the fringe fields of the other two magnets with a target current loss of no more than 16% with respect to the current obtained with no external magnetic fields. Conclusions: In this work, a specially designed electron gun was presented which can operate in the presence of axisymmetric strong magnetic fringe fields of MRI magnets. Computer simulations show that the electron gun can produce high quality beams which can be injected into a straight through linac such as Varian 600C and accelerated with more efficiency in the presence of the external magnetic fields. Also, the new configuration allows linac displacements along the magnet axis in a range equal to the diameter of the imaging spherical volume of the magnet under consideration. The new electron gun-linac system can function in the fringe field of a MRI magnet if the field strength at the cathode position is higher than 0.11 T. The capture efficiency of the linac depends on the magnetic field strength and the field gradient. The higher the gradient the better the capture efficiency. The capture efficiency does not degrade more than 16%.« less

A novel electron gun for inline MRI-linac configurations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Constantin, Dragoş E., E-mail: dragos.constantin@varian.com; Fahrig, Rebecca; Holloway, Lois

Purpose: This work introduces a new electron gun geometry capable of robust functioning in the presence of a high strength external magnetic field for axisymmetric magnetic resonance imaging (MRI)-linac configurations. This allows an inline MRI-linac to operate without the need to isolate the linear accelerator (linac) using a magnetic shield. This MRI-linac integration approach not only leaves the magnet homogeneity unchanged but also provides the linac flexibility to move along the magnet axis of symmetry if the source to target distance needs to be adjusted. Methods: Simple electron gun geometry modifications of a Varian 600C electron gun are considered andmore » solved in the presence of an external magnetic field in order to determine a set of design principles for the new geometry. Based on these results, a new gun geometry is proposed and optimized in the fringe field of a 0.5 T open bore MRI magnet (GE Signa SP). A computer model for the 6 MeV Varian 600C linac is used to determine the capture efficiency of the new electron gun-linac system in the presence of the fringe field of the same MRI scanner. The behavior of the new electron gun plus the linac system is also studied in the fringe fields of two other magnets, a 1.0 T prototype open bore magnet and a 1.5 T GE Conquest scanner. Results: Simple geometrical modifications of the original electron gun geometry do not provide feasible solutions. However, these tests show that a smaller transverse cathode diameter with a flat surface and a slightly larger anode diameter could alleviate the current loss due to beam interactions with the anode in the presence of magnetic fields. Based on these findings, an initial geometry resembling a parallel plate capacitor with a hole in the anode is proposed. The optimization procedure finds a cathode-anode distance of 5 mm, a focusing electrode angle of 5°, and an anode drift tube length of 17.1 mm. Also, the linac can be displaced with ±15 cm along the axis of the 0.5 T magnet without capture efficiency reduction below the experimental value in zero field. In this range of linac displacements, the electron beam generated by the new gun geometry is more effectively injected into the linac in the presence of an external magnetic field, resulting in approximately 20% increase of the target current compared to the original gun geometry behavior at zero field. The new gun geometry can generate and accelerate electron beams in external magnetic fields without current loss for fields higher than 0.11 T. The new electron-gun geometry is robust enough to function in the fringe fields of the other two magnets with a target current loss of no more than 16% with respect to the current obtained with no external magnetic fields. Conclusions: In this work, a specially designed electron gun was presented which can operate in the presence of axisymmetric strong magnetic fringe fields of MRI magnets. Computer simulations show that the electron gun can produce high quality beams which can be injected into a straight through linac such as Varian 600C and accelerated with more efficiency in the presence of the external magnetic fields. Also, the new configuration allows linac displacements along the magnet axis in a range equal to the diameter of the imaging spherical volume of the magnet under consideration. The new electron gun-linac system can function in the fringe field of a MRI magnet if the field strength at the cathode position is higher than 0.11 T. The capture efficiency of the linac depends on the magnetic field strength and the field gradient. The higher the gradient the better the capture efficiency. The capture efficiency does not degrade more than 16%.« less

Structural biologists capture detailed image of gene regulator’s fleeting form | Center for Cancer Research

Cancer.gov

Using an ultrafast, high-intensity radiation source called an X-ray free-electron laser (XFEL), scientists have captured an atomic-level picture of an RNA structure called a riboswitch as it reorganizes itself to regulate protein production. The structure they visualized has never before been seen, and likely exists for only milliseconds after the riboswitch first encounters

Effects of using structured templates for recalling chemistry experiments.

PubMed

Willoughby, Cerys; Logothetis, Thomas A; Frey, Jeremy G

2016-01-01

The way that we recall information is dependent upon both the knowledge in our memories and the conditions under which we recall the information. Electronic Laboratory Notebooks can provide a structured interface for the capture of experiment records through the use of forms and templates. These templates can be useful by providing cues to help researchers to remember to record particular aspects of their experiment, but they may also constrain the information that is recorded by encouraging them to record only what is asked for. It is therefore unknown whether using structured templates for capturing experiment records will have positive or negative effects on the quality and usefulness of the records for assessment and future use. In this paper we report on the results of a set of studies investigating the effects of different template designs on the recording of experiments by undergraduate students and academic researchers. The results indicate that using structured templates to write up experiments does make a significant difference to the information that is recalled and recorded. These differences have both positive and negative effects, with templates prompting the capture of specific information that is otherwise forgotten, but also apparently losing some of the personal elements of the experiment experience such as observations and explanations. Other unexpected effects were seen with templates that can change the information that is captured, but also interfere with the way an experiment is conducted. Our results showed that using structured templates can improve the completeness of the experiment context information captured but can also cause a loss of personal elements of the experiment experience when compared with allowing the researcher to structure their own record. The results suggest that interfaces for recording information about chemistry experiments, whether paper-based questionnaires or templates in Electronic Laboratory Notebooks, can be an effective way to improve the quality of experiment write-ups, but that care needs to be taken to ensure that the correct cues are provided.Graphical abstractScientists have traditionally recorded their research in paper notebooks, a format that provides great flexibility for capturing information. In contrast, Electronic Laboratory Notebooks frequently make use of forms or structured templates for capturing experiment records. Structured templates can provide cues that can improve record quality by increasing the amount of information captured and encouraging consistency. However, using the wrong cues can lead to a loss of personal elements of the experiment experience and frustrate users. This image shows two participants from one of our studies recording their experiment using a computer-based template.

Large electron capture-cross-section of the major nonradiative recombination centers in Mg-doped GaN epilayers grown on a GaN substrate

NASA Astrophysics Data System (ADS)

Chichibu, S. F.; Shima, K.; Kojima, K.; Takashima, S.; Edo, M.; Ueno, K.; Ishibashi, S.; Uedono, A.

2018-05-01

Complementary time-resolved photoluminescence and positron annihilation measurements were carried out at room temperature on Mg-doped p-type GaN homoepitaxial films for identifying the origin and estimating the electron capture-cross-section ( σ n ) of the major nonradiative recombination centers (NRCs). To eliminate any influence by threading dislocations, free-standing GaN substrates were used. In Mg-doped p-type GaN, defect complexes composed of a Ga-vacancy (VGa) and multiple N-vacancies (VNs), namely, VGa(VN)2 [or even VGa(VN)3], are identified as the major intrinsic NRCs. Different from the case of 4H-SiC, atomic structures of intrinsic NRCs in p-type and n-type GaN are different: VGaVN divacancies are the major NRCs in n-type GaN. The σ n value approximately the middle of 10-13 cm2 is obtained for VGa(VN)n, which is larger than the hole capture-cross-section (σp = 7 × 10-14 cm2) of VGaVN in n-type GaN. Combined with larger thermal velocity of an electron, minority carrier lifetime in Mg-doped GaN becomes much shorter than that of n-type GaN.

Development of tungsten-tantalum generator

NASA Technical Reports Server (NTRS)

Leblanc, A.; Babich, J.; Jhingran, S. G.

1985-01-01

The purpose of this project was to develop a useable tungsten (W)/tantalum (Ta) generator. Ta-178 is formed following the decay of its parent, W-178 (half-life: 21.7d) and has a half life of 9.3 minutes in turn yielding stable Hf-178. The decay of the parent isotope (W-178) occurs entirely by electron capture to the 9.3 minute Ta-178 state, without feeding the high spin Ta-178 isomer (half life 2.2 hours). In Ta-178 decay, 99.2% of the disintegrations proceed by electron capture and 0.18% by positron emission. Electron capture results in a 61.2% branch to the ground state of Hf-178 and 33.7% to the first excited state at 93 1KeV. The most prominent features of the radionuclide's energy spectrum are the hafnium characteristic radiation peaks with energies between 54.6 and 65.0 KeV. The radiation exposure dose of Ta-118 was calculated to be approximately one-twentieth that of Tc-99m on a per millicurie basis. A twenty-fold reduction in radiation exposure from Ta-178 compared with Tc-99m means that the usual administered dose can be increased three or four times, greatly increasing statistical accuracy while reducing radiation exposure by a factor of five.

Determining Steady-state Tissue Residues for Invertebrates in Contaminated Sediment

DTIC Science & Technology

2010-05-01

meter (Thermo Orion Electron Corp., Beverly, MA) equipped with a 95-12 ammonia sensitive electrode (Thermo Orion Electron Corp., Beverly, MA...analyzed using an Agilent 5890 gas chromatograph with electron capture detection. Metals were analyzed following methods 6010B and 6020 using a Perkin...readily into cyto- plasm , making it a strong candidate for biomagnification up the food chain (Mason et al. 1996; Wiener et al. 2003). The BSAF

The role of electron irradiation history in liquid cell transmission electron microscopy.

PubMed

Moser, Trevor H; Mehta, Hardeep; Park, Chiwoo; Kelly, Ryan T; Shokuhfar, Tolou; Evans, James E

2018-04-01

In situ liquid cell transmission electron microscopy (LC-TEM) allows dynamic nanoscale characterization of systems in a hydrated state. Although powerful, this technique remains impaired by issues of repeatability that limit experimental fidelity and hinder the identification and control of some variables underlying observed dynamics. We detail new LC-TEM devices that improve experimental reproducibility by expanding available imaging area and providing a platform for investigating electron flux history on the sample. Irradiation history is an important factor influencing LC-TEM results that has, to this point, been largely qualitatively and not quantitatively described. We use these devices to highlight the role of cumulative electron flux history on samples from both nanoparticle growth and biological imaging experiments and demonstrate capture of time zero, low-dose images on beam-sensitive samples. In particular, the ability to capture pristine images of biological samples, where the acquired image is the first time that the cell experiences significant electron flux, allowed us to determine that nanoparticle movement compared to the cell membrane was a function of cell damage and therefore an artifact rather than visualizing cell dynamics in action. These results highlight just a subset of the new science that is accessible with LC-TEM through the new multiwindow devices with patterned focusing aides.

The role of electron irradiation history in liquid cell transmission electron microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moser, Trevor H.; Mehta, Hardeep; Park, Chiwoo

In situ liquid cell transmission electron microscopy (LC-TEM) allows dynamic nanoscale characterization of systems in a hydrated state. Although powerful, this technique remains impaired by issues of repeatability that limit experimental fidelity and hinder the identification and control of some variables underlying observed dynamics. We detail new LC- TEM devices that improve experimental reproducibility by expanding available imaging area and providing a platform for investigating electron flux history on the sample. Irradiation history is an important factor influencing LC-TEM results that has, to this point, been largely qualitatively and not quantitatively described. We use these devices to highlight the rolemore » of cumulative electron flux history on samples from both nanoparticle growth and biological imaging experiments and demonstrate capture of time zero, low-dose images on beam-sensitive samples. In particular, the ability to capture pristine images of biological samples, where the acquired image is the first time that the cell experiences significant electron flux, allowed us to determine that nanoparticle movement compared to the cell membrane was a function of cell damage and therefore an artifact rather than visualizing cell dynamics in action. These results highlight just a subset of the new science that is accessible with LC-TEM through the new multiwindow devices with patterned focusing aides.« less

The role of electron irradiation history in liquid cell transmission electron microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moser, Trevor H.; Mehta, Hardeep; Park, Chiwoo

In situ liquid cell transmission electron microscopy (LC-TEM) allows dynamic nanoscale characterization of systems in a hydrated state. Although powerful, this technique remains impaired by issues of repeatability that limit experimental fidelity and hinder the identification and control of some variables underlying observed dynamics. We detail new LC-TEM devices that improve experimental reproducibility by expanding available imaging area and providing a platform for investigating electron flux history on the sample. Irradiation history is an important factor influencing LC-TEM results that has, to this point, been largely qualitatively and not quantitatively described. We use these devices to highlight the role ofmore » cumulative electron flux history on samples from both nanoparticle growth and biological imaging experiments and demonstrate capture of time zero, low-dose images on beam-sensitive samples. In particular, the ability to capture pristine images of biological samples, where the acquired image is the first time that the cell experiences significant electron flux, allowed us to determine that nanoparticle movement compared to the cell membrane was a function of cell damage and therefore an artifact rather than visualizing cell dynamics in action. Lastly, these results highlight just a subset of the new science that is accessible with LC-TEM through the new multiwindow devices with patterned focusing aides.« less

Electronic Information Standards to Support Obesity Prevention and Bridge Services Across Systems, 2010-2015.

PubMed

Wiltz, Jennifer L; Blanck, Heidi M; Lee, Brian; Kocot, S Lawrence; Seeff, Laura; McGuire, Lisa C; Collins, Janet

2017-10-26

Electronic information technology standards facilitate high-quality, uniform collection of data for improved delivery and measurement of health care services. Electronic information standards also aid information exchange between secure systems that link health care and public health for better coordination of patient care and better-informed population health improvement activities. We developed international data standards for healthy weight that provide common definitions for electronic information technology. The standards capture healthy weight data on the "ABCDs" of a visit to a health care provider that addresses initial obesity prevention and care: assessment, behaviors, continuity, identify resources, and set goals. The process of creating healthy weight standards consisted of identifying needs and priorities, developing and harmonizing standards, testing the exchange of data messages, and demonstrating use-cases. Healthy weight products include 2 message standards, 5 use-cases, 31 LOINC (Logical Observation Identifiers Names and Codes) question codes, 7 healthy weight value sets, 15 public-private engagements with health information technology implementers, and 2 technical guides. A logic model and action steps outline activities toward better data capture, interoperable systems, and information use. Sharing experiences and leveraging this work in the context of broader priorities can inform the development of electronic information standards for similar core conditions and guide strategic activities in electronic systems.

Electronic Information Standards to Support Obesity Prevention and Bridge Services Across Systems, 2010–2015

PubMed Central

Blanck, Heidi M.; Lee, Brian; Kocot, S. Lawrence; Seeff, Laura; McGuire, Lisa C.; Collins, Janet

2017-01-01

Electronic information technology standards facilitate high-quality, uniform collection of data for improved delivery and measurement of health care services. Electronic information standards also aid information exchange between secure systems that link health care and public health for better coordination of patient care and better-informed population health improvement activities. We developed international data standards for healthy weight that provide common definitions for electronic information technology. The standards capture healthy weight data on the “ABCDs” of a visit to a health care provider that addresses initial obesity prevention and care: assessment, behaviors, continuity, identify resources, and set goals. The process of creating healthy weight standards consisted of identifying needs and priorities, developing and harmonizing standards, testing the exchange of data messages, and demonstrating use-cases. Healthy weight products include 2 message standards, 5 use-cases, 31 LOINC (Logical Observation Identifiers Names and Codes) question codes, 7 healthy weight value sets, 15 public–private engagements with health information technology implementers, and 2 technical guides. A logic model and action steps outline activities toward better data capture, interoperable systems, and information use. Sharing experiences and leveraging this work in the context of broader priorities can inform the development of electronic information standards for similar core conditions and guide strategic activities in electronic systems. PMID:29072985

The role of electron irradiation history in liquid cell transmission electron microscopy

PubMed Central

Mehta, Hardeep

2018-01-01

In situ liquid cell transmission electron microscopy (LC-TEM) allows dynamic nanoscale characterization of systems in a hydrated state. Although powerful, this technique remains impaired by issues of repeatability that limit experimental fidelity and hinder the identification and control of some variables underlying observed dynamics. We detail new LC-TEM devices that improve experimental reproducibility by expanding available imaging area and providing a platform for investigating electron flux history on the sample. Irradiation history is an important factor influencing LC-TEM results that has, to this point, been largely qualitatively and not quantitatively described. We use these devices to highlight the role of cumulative electron flux history on samples from both nanoparticle growth and biological imaging experiments and demonstrate capture of time zero, low-dose images on beam-sensitive samples. In particular, the ability to capture pristine images of biological samples, where the acquired image is the first time that the cell experiences significant electron flux, allowed us to determine that nanoparticle movement compared to the cell membrane was a function of cell damage and therefore an artifact rather than visualizing cell dynamics in action. These results highlight just a subset of the new science that is accessible with LC-TEM through the new multiwindow devices with patterned focusing aides. PMID:29725619

The role of electron irradiation history in liquid cell transmission electron microscopy

DOE PAGES

Moser, Trevor H.; Mehta, Hardeep; Park, Chiwoo; ...

2018-04-20

In situ liquid cell transmission electron microscopy (LC-TEM) allows dynamic nanoscale characterization of systems in a hydrated state. Although powerful, this technique remains impaired by issues of repeatability that limit experimental fidelity and hinder the identification and control of some variables underlying observed dynamics. We detail new LC-TEM devices that improve experimental reproducibility by expanding available imaging area and providing a platform for investigating electron flux history on the sample. Irradiation history is an important factor influencing LC-TEM results that has, to this point, been largely qualitatively and not quantitatively described. We use these devices to highlight the role ofmore » cumulative electron flux history on samples from both nanoparticle growth and biological imaging experiments and demonstrate capture of time zero, low-dose images on beam-sensitive samples. In particular, the ability to capture pristine images of biological samples, where the acquired image is the first time that the cell experiences significant electron flux, allowed us to determine that nanoparticle movement compared to the cell membrane was a function of cell damage and therefore an artifact rather than visualizing cell dynamics in action. Lastly, these results highlight just a subset of the new science that is accessible with LC-TEM through the new multiwindow devices with patterned focusing aides.« less

γ{\\hbox-}Flash suppression using a gated photomultiplier assembled with an LaBr3(Ce) detector to measure fast neutron capture reactions

NASA Astrophysics Data System (ADS)

Hara, K. Y.; Harada, H.; Toh, Y.; Hori, J.

2013-09-01

A gated photomultiplier tube (PMT) assembled with an LaBr3(Ce) detector was applied toward the prompt γ{hbox-}ray measurement of fast neutron capture reactions. Time-of-flight measurements of the neutron capture reactions of Cl and Al were performed using the 46-MeV electron linear accelerator at the Kyoto University Research Reactor Institute (KURRI) as a pulsed neutron source. The photomultiplier gating technique effectively suppressed the saturation of the PMT output and extended the energy region of the TOF measurement.

Can one measure the Cosmic Neutrino Background?

NASA Astrophysics Data System (ADS)

Faessler, Amand; Hodák, Rastislav; Kovalenko, Sergey; Šimkovic, Fedor

The Cosmic Microwave Background (CMB) yields information about our Universe at around 380,000 years after the Big Bang (BB). Due to the weak interaction of the neutrinos with matter, the Cosmic Neutrino Background (CNB) should give information about a much earlier time of our Universe, around one second after the BB. Probably, the most promising method to “see” the CNB is the capture of the electron neutrinos from the Background by Tritium, which then decays into 3He and an electron with the energy of the the Q-value = 18.562keV plus the electron neutrino rest mass. The “KArlsruhe TRItium Neutrino” (KATRIN) experiment, which is in preparation, seems presently the most sensitive proposed method for measuring the electron antineutrino mass. At the same time, KATRIN can also look by the reaction νe(˜ 1.95K) +3H →3He + e-(Q = 18.6keV + m νec2). The capture of the Cosmic Background Neutrinos (CNB) should show in the electron spectrum as a peak by the electron neutrino rest mass above Q. Here, the possibility to see the CNB with KATRIN is studied. A detection of the CNB by KATRIN seems not to be possible at the moment. But KATRIN should be able to determine an upper limit for the local electron neutrino density of the CNB.

Can one measure the Cosmic Neutrino Background?

NASA Astrophysics Data System (ADS)

Faessler, Amand; Hodák, Rastislav; Kovalenko, Sergey; Šimkovic, Fedor

The Cosmic Microwave Background (CMB) yields information about our Universe at around 380,000 years after the Big Bang (BB). Due to the weak interaction of the neutrinos with matter, the Cosmic Neutrino Background (CNB) should give information about a much earlier time of our Universe, around one second after the BB. Probably, the most promising method to "see" the CNB is the capture of the electron neutrinos from the Background by Tritium, which then decays into 3He and an electron with the energy of the the Q-value = 18.562 keV plus the electron neutrino rest mass. The "KArlsruhe TRItium Neutrino" (KATRIN) experiment, which is in preparation, seems presently the most sensitive proposed method for measuring the electron antineutrino mass. At the same time, KATRIN can also look by the reaction νe(˜1.95K) + 3H → 3He + e-(Q = 18.6keV + mνec2). The capture of the Cosmic Background Neutrinos (CNB) should show in the electron spectrum as a peak by the electron neutrino rest mass above Q. Here, the possibility to see the CNB with KATRIN is studied. A detection of the CNB by KATRIN seems not to be possible at the moment. But KATRIN should be able to determine an upper limit for the local electron neutrino density of the CNB.

Constraining Nuclear Weak Interactions in Astrophysics and New Many-Core Algorithms for Neuroevolution

NASA Astrophysics Data System (ADS)

Sullivan, Christopher James

Weak interactions involving atomic nuclei are critical components in a broad range of as- trophysical phenomenon. As allowed Gamow-Teller transitions are the primary path through which weak interactions in nuclei operate in astrophysical contexts, the constraint of these nuclear transitions is an important goal of nuclear astrophysics. In this work, the charged current nuclear weak interaction known as electron capture is studied in the context of stellar core-collapse supernovae (CCSNe). Specifically, the sensitivity of the core-collapse and early post-bounce phases of CCSNe to nuclear electron capture rates are examined. Electron capture rates are adjusted by factors consistent with uncer- tainties indicated by comparing theoretical rates to those deduced from charge-exchange and beta-decay measurements. With the aide of such sensitivity studies, the diverse role of electron capture on thousands of nuclear species is constrained to a few tens of nuclei near N 50 and A 80 which dictate the primary response of CCSNe to nuclear electron capture. As electron capture is shown to be a leading order uncertainty during the core-collapse phase of CCSNe, future experimental and theoretical efforts should seek to constrain the rates of nuclei in this region. Furthermore, neutral current neutrino-nuclear interactions in the tens-of-MeV energy range are important in a variety of astrophysical environments including core-collapse super- novae as well as in the synthesis of some of the solar systems rarest elements. Estimates for inelastic neutrino scattering on nuclei are also important for neutrino detector construction aimed at the detection of astrophysical neutrinos. Due to the small cross sections involved, direct measurements are rare and have only been performed on a few nuclei. For this rea- son, indirect measurements provide a unique opportunity to constrain the nuclear transition strength needed to infer inelastic neutrino-nucleus cross sections. Herein the (6Li, 6Li‧) inelastic scattering reaction at 100 MeV/u is shown to indirectly select the relevant transitions for inelastic neutrino-nucleus scattering. Specifically, the probes unique selectivity of isovector- spin transfer excitations (Delta S = 1, DeltaT = 1, DeltaTz = 0) is demonstrated, thereby allowing the extraction of Gamow-Teller transition strength in the inelastic channel. Finally, the development and performance of a newly established technique for the sub- field of artificial intelligence known as neuroevolution is described. While separate from the physics that is discussed, these algorithmic advancements seek to improve the adoption of machine learning in the scientific domain by enabling neuroevolution to take advantage of modern heterogeneous compute architectures. Because the evolution of neural network pop- ulations offloads the choice of specific details about the neural networks to an evolutionary search algorithm, neuroevolution can increase the accessibility of machine learning. However, the evolution of neural networks through parameter and structural space presents a novel di- vergence problem when mapping the evaluation of these networks to many-core architectures. The principal focus of the algorithm optimizations described herein are on improving the feed-forward evaluation time when tens-to-hundreds of thousands of heterogeneous neural networks are evaluated concurrently.

Effect of nuclear shielding in collision of positive charged helium ions with helium atoms

NASA Astrophysics Data System (ADS)

Ghavaminia, Hoda; Ghavaminia, Shirin

2018-03-01

Differential in angle and absolute cross sections in energy of the scattered particles are obtained for single charge exchange in ^3He^+-^4He collisions by means of the four body boundary-corrected first Born approximation (CB1-4B). The quantum-mechanical post and prior transition amplitudes are derived in terms of two-dimensional real integrals in the case of the prior form and five-dimensional quadratures for the post form. The effect of the dynamic electron correlation through the complete perturbation potential and the nuclear-screening influence of the passive electrons on the electron capture process is investigated. The results obtained in the CB1-4B method are compared with the available experimental data. For differential cross sections, the present results are in better agreement with experimental data than other theoretical data at extreme forward scattering angles. The integral cross sections are in excellent agreement with the experiment. Also, total cross sections for single electron capture, has been investigated using the classical trajectory Monte Carlo method. The present calculated results are found to be in an excellent agreement with the experimental data.

Carrier-density-dependent recombination dynamics of excitons and electron-hole plasma in m -plane InGaN/GaN quantum wells

NASA Astrophysics Data System (ADS)

Liu, W.; Butté, R.; Dussaigne, A.; Grandjean, N.; Deveaud, B.; Jacopin, G.

2016-11-01

We study the carrier-density-dependent recombination dynamics in m -plane InGaN/GaN multiple quantum wells in the presence of n -type background doping by time-resolved photoluminescence. Based on Fermi's golden rule and Saha's equation, we decompose the radiative recombination channel into an excitonic and an electron-hole pair contribution, and extract the injected carrier-density-dependent bimolecular recombination coefficients. Contrary to the standard electron-hole picture, our results confirm the strong influence of excitons even at room temperature. Indeed, at 300 K, excitons represent up to 63 ± 6% of the photoexcited carriers. In addition, following the Shockley-Read-Hall model, we extract the electron and hole capture rates by deep levels and demonstrate that the increase in the effective lifetime with injected carrier density is due to asymmetric capture rates in presence of an n -type background doping. Thanks to the proper determination of the density-dependent recombination coefficients up to high injection densities, our method provides a way to evaluate the importance of Auger recombination.

Investigation of the Mechanism of Electron Capture and Electron Transfer Dissociation of Peptides with a Covalently Attached Free Radical Hydrogen Atom Scavenger.

PubMed

Sohn, Chang Ho; Yin, Sheng; Peng, Ivory; Loo, Joseph A; Beauchamp, J L

2015-11-15

The mechanisms of electron capture and electron transfer dissociation (ECD and ETD) are investigated by covalently attaching a free-radical hydrogen atom scavenger to a peptide. The 2,2,6,6-tetramethylpiperidin-l-oxyl (TEMPO) radical was chosen as the scavenger due to its high hydrogen atom affinity (ca. 280 kJ/mol) and low electron affinity (ca. 0.45 ev), and was derivatized to the model peptide, FQX TEMPO EEQQQTEDELQDK. The X TEMPO residue represents a cysteinyl residue derivatized with an acetamido-TEMPO group. The acetamide group without TEMPO was also examined as a control. The gas phase proton affinity (882 kJ/mol) of TEMPO is similar to backbone amide carbonyls (889 kJ/mol), minimizing perturbation to internal solvation and sites of protonation of the derivatized peptides. Collision induced dissociation (CID) of the TEMPO tagged peptide dication generated stable odd-electron b and y type ions without indication of any TEMPO radical induced fragmentation initiated by hydrogen abstraction. The type and abundance of fragment ions observed in the CID spectra of the TEMPO and acetamide tagged peptides are very similar. However, ECD of the TEMPO labeled peptide dication yielded no backbone cleavage. We propose that a labile hydrogen atom in the charge reduced radical ions is scavenged by the TEMPO radical moiety, resulting in inhibition of N-C α backbone cleavage processes. Supplemental activation after electron attachment (ETcaD) and CID of the charge-reduced precursor ion generated by electron transfer of the TEMPO tagged peptide dication produced a series of b + H (b H ) and y + H (y H ) ions along with some c ions having suppressed intensities, consistent with stable O-H bond formation at the TEMPO group. In summary, the results indicate that ECD and ETD backbone cleavage processes are inhibited by scavenging of a labile hydrogen atom by the localized TEMPO radical moiety. This observation supports the conjecture that ECD and ETD processes involve long-lived intermediates formed by electron capture/transfer in which a labile hydrogen atom is present and plays a key role with low energy processes leading to c and z ion formation. Ab initio and density functional calculations are performed to support our conclusion, which depends most importantly on the proton affinity, electron affinity and hydrogen atom affinity of the TEMPO moiety.

Visualizing Ebolavirus Particles Using Single-Particle Interferometric Reflectance Imaging Sensor (SP-IRIS).

PubMed

Carter, Erik P; Seymour, Elif Ç; Scherr, Steven M; Daaboul, George G; Freedman, David S; Selim Ünlü, M; Connor, John H

2017-01-01

This chapter describes an approach for the label-free imaging and quantification of intact Ebola virus (EBOV) and EBOV viruslike particles (VLPs) using a light microscopy technique. In this technique, individual virus particles are captured onto a silicon chip that has been printed with spots of virus-specific capture antibodies. These captured virions are then detected using an optical approach called interference reflectance imaging. This approach allows for the detection of each virus particle that is captured on an antibody spot and can resolve the filamentous structure of EBOV VLPs without the need for electron microscopy. Capture of VLPs and virions can be done from a variety of sample types ranging from tissue culture medium to blood. The technique also allows automated quantitative analysis of the number of virions captured. This can be used to identify the virus concentration in an unknown sample. In addition, this technique offers the opportunity to easily image virions captured from native solutions without the need for additional labeling approaches while offering a means of assessing the range of particle sizes and morphologies in a quantitative manner.

Structural biologists capture detailed image of gene regulator’s fleeting form | Center for Cancer Research

Cancer.gov

Using an ultrafast, high-intensity radiation source called an X-ray free-electron laser (XFEL), scientists have captured an atomic-level picture of an RNA structure called a riboswitch as it reorganizes itself to regulate protein production. The structure they visualized has never before been seen, and likely exists for only milliseconds after the riboswitch first encounters its activating molecule.  Read more...  

Electronic Equipment Proposal to Improve the Photovoltaic Systems Efficiency

NASA Astrophysics Data System (ADS)

Flores-Mena, J. E.; Juárez Morán, L. A.; Díaz Reyes, J.

2011-05-01

This paper reports a new technique proposal to improve the photovoltaic systems. It was made to design and implement an electronic system that will detect, capture, and transfer the maximum power of the photovoltaic (PV) panel to optimize the supplied power of a solar panel. The electronic system works on base technical proposal of electrical sweeping of electric characteristics using capacitive impedance. The maximum power is transformed and the solar panel energy is sent to an automotive battery. This electronic system reduces the energy lost originated when the solar radiation level decreases or the PV panel temperature is increased. This electronic system tracks, captures, and stores the PV module's maximum power into a capacitor. After, a higher voltage level step-up circuit was designed to increase the voltage of the PV module's maximum power and then its current can be sent to a battery. The experimental results show that the developed electronic system has 95% efficiency. The measurement was made to 50 W, the electronic system works rightly with solar radiation rate from 100 to 1,000 W m - 2 and the PV panel temperature rate changed from 1 to 75°C. The main advantage of this electronic system compared with conventional methods is the elimination of microprocessors, computers, and sophisticated numerical approximations, and it does not need any small electrical signals to track the maximum power. The proposed method is simple, fast, and it is also cheaper.

Preparation of graphene thin films for radioactive samples.

PubMed

Roteta, Miguel; Fernández-Martínez, Rodolfo; Mejuto, Marcos; Rucandio, Isabel

2016-03-01

A new method for the preparation of conductive thin films is presented. The metallization of VYNS films guarantees the electrical conductivity but it results in the breaking of a high proportion of them. Graphene, a two-dimensional nanostructure of monolayer or few layers graphite has attracted a great deal of attention because of its excellent properties such as a good chemical stability, mechanical resistance and extraordinary electronic transport properties. In this work, the possibilities of graphene have been explored as a way to produce electrical conductive thin films without an extra metallization process. The procedure starts with preparing homogenous suspensions of reduced graphene oxide (rGO) in conventional VYNS solutions. Ultra-sonication is used to ensure a good dispersibility of rGO. Graphene oxide (GO) is prepared via oxidation of graphite and subsequent exfoliation by sonication. Different chemically rGO were obtained by reaction with hydrazine sulfate, sodium borohydride, ascorbic acid and hydroiodic acid as reducing agents. The preparation of the thin graphene films is done in a similar way as the conventional VYNS foil preparation procedure. Drops of the solution are deposited onto water. The graphene films have been used to prepare sources containing some electron capture radionuclides ((109)Cd, (55)Fe, (139)Ce) with an activity in the order of 3kBq. The samples have been measured to test the attainable low energy electron efficiency and the energy resolution of Auger and conversion electrons by 4π (electron capture)-γ coincidence measurements. The 4π (electron capture)-γ coincidence setup includes a pressurized proportional counter and a NaI(Tl) detector. Tests with different pressures up to 1000kPa were carried out. All these tests show similar values in both parameters (efficiency and resolution) as those obtained by using the conventional metallized films without the drawback of the high percentage of broken films. Copyright © 2015 Elsevier Ltd. All rights reserved.

High Pressure Gas Filled RF Cavity Beam Test at the Fermilab MuCool Test Area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freemire, Ben

2013-05-01

The high energy physics community is continually looking to push the limits with respect to the energy and luminosity of particle accelerators. In the realm of leptons, only electron colliders have been built to date. Compared to hadrons, electrons lose a large amount of energy when accelerated in a ring through synchrotron radiation. A solution to this problem is to build long, straight accelerators for electrons, which has been done with great success. With a new generation of lepton colliders being conceived, building longer, more powerful accelerators is not the most enticing option. Muons have been proposed as an alternativemore » particle to electrons. Muons lose less energy to synchrotron radiation and a Muon Collider can provide luminosity within a much smaller energy range than a comparable electron collider. This allows a circular collider to be built with higher attainable energy than any present electron collider. As part of the accelerator, but separate from the collider, it would also be possible to allow the muons to decay to study neutrinos. The possibility of a high energy, high luminosity muon collider and an abundant, precise source of neutrinos is an attractive one. The technological challenges of building a muon accelerator are many and diverse. Because the muon is an unstable particle, a muon beam must be cooled and accelerated to the desired energy within a short amount of time. This requirement places strict requisites on the type of acceleration and focusing that can be used. Muons are generated as tertiary beams with a huge phase space, so strong magnetic fields are required to capture and focus them. Radio frequency (RF) cavities are needed to capture, bunch and accelerate the muons. Unfortunately, traditional vacuum RF cavities have been shown to break down in the magnetic fields necessary for capture and focusing.« less

Electron capture rates in stars studied with heavy ion charge exchange reactions

NASA Astrophysics Data System (ADS)

Bertulani, C. A.

2018-01-01

Indirect methods using nucleus-nucleus reactions at high energies (here, high energies mean ~ 50 MeV/nucleon and higher) are now routinely used to extract information of interest for nuclear astrophysics. This is of extreme relevance as many of the nuclei involved in stellar evolution are short-lived. Therefore, indirect methods became the focus of recent studies carried out in major nuclear physics facilities. Among such methods, heavy ion charge exchange is thought to be a useful tool to infer Gamow-Teller matrix elements needed to describe electron capture rates in stars and also double beta-decay experiments. In this short review, I provide a theoretical guidance based on a simple reaction model for charge exchange reactions.

The concept of quasi-tissue-equivalent nanodosimeter based on the glow peak 5a/5 in LiF:Mg,Ti (TLD-100).

PubMed

Oster, L; Horowitz, Y S; Biderman, S; Haddad, J

2003-12-01

We demonstrate the viability of the concept of using existing molecular nanostructures in thermoluminescent solid-state materials as solid-state nanodosimeters. The concept is based on mimicking radiobiology (specifically the ionization density dependence of double strand breaks in DNA) by using the similar ionization density dependence of simultaneous electron-hole capture in spatially correlated trapping and luminescent centres pairs in the thermoluminescence of LiF:Mg,Ti. This simultaneous electron-hole capture has been shown to lead to ionization density dependence in the relative intensity of peak 5a to peak 5 similar to the ratio of double-strand breaks to single-strand breaks for low energy He ions.

Optical pumping and negative luminescence polarization in charged GaAs quantum dots

NASA Astrophysics Data System (ADS)

Shabaev, Andrew; Stinaff, Eric A.; Bracker, Allan S.; Gammon, Daniel; Efros, Alexander L.; Korenev, Vladimir L.; Merkulov, Igor

2009-01-01

Optical pumping of electron spins and negative photoluminescence polarization are observed when interface quantum dots in a GaAs quantum well are excited nonresonantly by circularly polarized light. Both observations can be explained by the formation of long-lived dark excitons through hole spin relaxation in the GaAs quantum well prior to exciton capture. In this model, optical pumping of resident electron spins is caused by capture of dark excitons and recombination in charged quantum dots. Negative polarization results from accumulation of dark excitons in the quantum well and is enhanced by optical pumping. The dark exciton model describes the experimental results very well, including intensity and bias dependence of the photoluminescence polarization and the Hanle effect.

Supporting research sites in resource-limited settings: challenges in implementing information technology infrastructure.

PubMed

Whalen, Christopher J; Donnell, Deborah; Tartakovsky, Michael

2014-01-01

As information and communication technology infrastructure becomes more reliable, new methods of electronic data capture, data marts/data warehouses, and mobile computing provide platforms for rapid coordination of international research projects and multisite studies. However, despite the increasing availability of Internet connectivity and communication systems in remote regions of the world, there are still significant obstacles. Sites with poor infrastructure face serious challenges participating in modern clinical and basic research, particularly that relying on electronic data capture and Internet communication technologies. This report discusses our experiences in supporting research in resource-limited settings. We describe examples of the practical and ethical/regulatory challenges raised by the use of these newer technologies for data collection in multisite clinical studies.

Photophysical Properties on Functional Pi-Electronic Molecular Systems

DTIC Science & Technology

2012-08-01

the aromaticity; i) it is possible to control the number of conjugated π-electrons by changing the number of connected pyrrole rings, ii) by...flexibilities, and facile capture and release of two pyrrolic protons upon two-electron oxidation and reduction, respectively. Scheme 2. (a...nitrogen atoms of pyrrole A, B, C and D, and the ortho-carbon atom of meso-pentafluorophenyl group in a trigonal bipyramidal manner. The 1 H NMR spectrum

The Demonstration of the Feasibility of the Tuning and Stimulation of Nuclear Radiation.

DTIC Science & Technology

1988-10-31

line, or the center of a resonance pattern, is called the isomer shift. It is due to the electrostatic interaction of the nucleus with the electron ...magnetic moment due to the presence of unpaired electrons , the material is either paramagnetic or ferromagnetic. In paramagnetic materials these moments...capture and fission.4,5,8 A very fertile interdisciplinary area of nuclear quantum electronics 7 appeared to be developing, encouraged by the

Comment on: Negative ions, molecular electron affinity and orbital structure of cata-condensed polycyclic aromatic hydrocarbons by Rustem V. Khatymov, Mars V. Muftakhov and Pavel V. Shchukin.

PubMed

Chen, Edward S; Chen, Edward C M

2018-02-15

The anion mass spectral lifetimes for several aromatic hydrocarbons reported in the subject article were related to significantly different electron affinities. The different values are rationalized using negative ion mass spectral data. Electron affinities for polycyclic aromatic hydrocarbons are reported from the temperature dependence of unpublished electron capture detector data. These are compared with published values and the largest values are assigned to the ground state. The ground state adiabatic electron affinities: (eV) pentacene, 1.41 (3); tetracene, 1.058 (5); benz(a)pyrene, 0.82 (4); benz(a) anthracene, 0.69 (2) anthracene, 0.68 (2); and pyrene, 0.59 (1) are used to assign excited state adiabatic electron affinities: (eV) tetracene: 0.88 (4); anthracene 0.53 (1); pyrene, 0.41 (1); benz(a)anthracene, 0.39 (10); chrysene, 0.32 (1); and phenanthrene, 0.12 (2) and ground state adiabatic electron affinities: (eV) dibenz(a,j)anthracene, 0.69 (3); dibenz(a,h)anthracene, 0.68 (3); benz(e)pyrene, 0.60 (3); and picene, 0.59 (3) from experimental data. The lifetime of benz(a)pyrene is predicted to be larger than 150 μs and for benzo(c)phenanthrene and picene about 40 μs, from ground state adiabatic electron affinities. The assignments of adiabatic electron affinities of aromatic hydrocarbons determined from electron capture detector and mass spectrometric data to ground and excited states are supported by constant electronegativities. A set of consistent ground state adiabatic electron affinities for 15 polycyclic aromatic hydrocarbons is related to lifetimes from the subject article. Copyright © 2017 John Wiley & Sons, Ltd.

High-resolution, high-throughput imaging with a multibeam scanning electron microscope

PubMed Central

EBERLE, AL; MIKULA, S; SCHALEK, R; LICHTMAN, J; TATE, ML KNOTHE; ZEIDLER, D

2015-01-01

Electron–electron interactions and detector bandwidth limit the maximal imaging speed of single-beam scanning electron microscopes. We use multiple electron beams in a single column and detect secondary electrons in parallel to increase the imaging speed by close to two orders of magnitude and demonstrate imaging for a variety of samples ranging from biological brain tissue to semiconductor wafers. Lay Description The composition of our world and our bodies on the very small scale has always fascinated people, making them search for ways to make this visible to the human eye. Where light microscopes reach their resolution limit at a certain magnification, electron microscopes can go beyond. But their capability of visualizing extremely small features comes at the cost of a very small field of view. Some of the questions researchers seek to answer today deal with the ultrafine structure of brains, bones or computer chips. Capturing these objects with electron microscopes takes a lot of time – maybe even exceeding the time span of a human being – or new tools that do the job much faster. A new type of scanning electron microscope scans with 61 electron beams in parallel, acquiring 61 adjacent images of the sample at the same time a conventional scanning electron microscope captures one of these images. In principle, the multibeam scanning electron microscope’s field of view is 61 times larger and therefore coverage of the sample surface can be accomplished in less time. This enables researchers to think about large-scale projects, for example in the rather new field of connectomics. A very good introduction to imaging a brain at nanometre resolution can be found within course material from Harvard University on http://www.mcb80x.org/# as featured media entitled ‘connectomics’. PMID:25627873

Proportional counter device for detecting electronegative species in an air sample

DOEpatents

Allman, Steve L.; Chen, Fang C.; Chen, Chung-Hsuan

1994-01-01

Apparatus for detecting an electronegative species comprises an analysis chamber, an inlet communicating with the analysis chamber for admitting a sample containing the electronegative species and an ionizable component, a radioactive source within the analysis chamber for emitting radioactive energy for ionizing a component of the sample, a proportional electron detector within the analysis chamber for detecting electrons emitted from the ionized component, and a circuit for measuring the electrons and determining the presence of the electronegative species by detecting a reduction in the number of available electrons due to capture of electrons by the electronegative species.

Proportional counter device for detecting electronegative species in an air sample

DOEpatents

Allman, S.L.; Chen, F.C.; Chen, C.H.

1994-03-08

Apparatus for detecting an electronegative species comprises an analysis chamber, an inlet communicating with the analysis chamber for admitting a sample containing the electronegative species and an ionizable component, a radioactive source within the analysis chamber for emitting radioactive energy for ionizing a component of the sample, a proportional electron detector within the analysis chamber for detecting electrons emitted from the ionized component, and a circuit for measuring the electrons and determining the presence of the electronegative species by detecting a reduction in the number of available electrons due to capture of electrons by the electronegative species. 2 figures.

ERCS08: A FORTRAN program equipped with a Windows graphics user interface that calculates ECPSSR cross sections for the removal of atomic electrons

NASA Astrophysics Data System (ADS)

Horvat, Vladimir

2009-06-01

ERCS08 is a program for computing the atomic electron removal cross sections. It is written in FORTRAN in order to make it more portable and easier to customize by a large community of physicists, but it also comes with a separate windows graphics user interface control application ERCS08w that makes it easy to quickly prepare the input file, run the program, as well as view and analyze the output. The calculations are based on the ECPSSR theory for direct (Coulomb) ionization and non-radiative electron capture. With versatility in mind, the program allows for selective inclusion or exclusion of individual contributions to the cross sections from effects such as projectile energy loss, Coulomb deflection of the projectile, perturbation of electron's stationary state (polarization and binding), as well as relativity. This makes it straightforward to assess the importance of each effect in a given collision regime. The control application also makes it easy to setup for calculations in inverse kinematics (i.e. ionization of projectile ions by target atoms or ions). Program summaryProgram title: ERCS08 Catalogue identifier: AECU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AECU_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 12 832 No. of bytes in distributed program, including test data, etc.: 318 420 Distribution format: tar.gz Programming language: Once the input file is prepared (using a text editor or ERCS08w), all the calculations are done in FORTRAN using double precision. Computer: see "Operating system" below Operating system: The main program (ERCS08) can run on any computer equipped with a FORTRAN compiler. Its pre-compiled executable file (supplied) runs under DOS or Windows. The supplied graphics user interface control application (ERCS08w) requires a Windows operating system. ERCS08w is designed to be used along with a text editor. Any editor can be used, including the one that comes with the operating system (for example, Edit for DOS or Notepad for Windows). Classification: 16.7, 16.8 Nature of problem: ECPSSR has become a typical tag word for a theory that goes beyond the standard plane wave Born approximation (PWBA) in order to predict the cross sections for direct (Coulomb) ionization of atomic electrons by projectile ions, taking into account the energy loss (E) and Coulomb deflection (C) of the projectile, as well as the perturbed stationary state (PSS) and relativistic nature (R) of the target electron. Its treatment of non-radiative electron capture to the projectile goes beyond the Oppenheimer-Brinkman-Kramers approximation (OBK) to include the effects of C, PSS, and R. PSS is described in terms of increased target electron binding (B) due to the presence of the projectile in the vicinity of the target nucleus, and (for direct ionization only) polarization of the target electron cloud (P) while projectile is outside the electron's shell radius. Several modifications of the theory have been recently suggested or endorsed by one of its authors (Lapicki). These modifications are sometimes explicit in the tag word (for example, eCPSSR, eCUSR, ReCPSShsR, etc.) A cross section for the ionization of a target electron is assumed to equal the sum of the cross sections for direct ionization (DI) and electron capture (EC). Solution method: The calculations are based on the ECPSSR theory for direct (Coulomb) ionization and non-radiative electron capture. With versatility in mind, the program allows for selective inclusion or exclusion of individual contributions to the cross sections from effects such as projectile energy loss, Coulomb deflection of the projectile, perturbation of electron's stationary state (polarization and binding), as well as relativity. This makes it straightforward to assess the importance of each effect in a given collision regime. The control application also makes it easy to setup for calculations in inverse kinematics (i.e. ionization of projectile ions by target atoms or ions). Restrictions: The program is restricted to the ionization of K, L, and M electrons. The theory is non-relativistic, which effectively limits its applicability to projectile energies up to about 50 MeV/amu. However, the theory is extended to apply to relativistic light projectiles. Radiative electron capture is not taken into account, since its contribution is found to be negligible in the collision regimes covered by the ECPSSR theory. Unusual features: Windows graphics user interface along with a FORTRAN code for calculations, selective inclusion or exclusion of specific corrections, inclusion of the extension to relativistic light projectiles, inclusion of non-radiative electron capture. Running time: Running the program using the input data provided with the distribution only takes a few seconds.

NOR-DMARD data management: implementation of data capture from electronic health records.

PubMed

Olsen, I C; Haavardsholm, E A; Moholt, E; Kvien, T K; Lie, E

2014-01-01

The use of electronic health records (EHR) is an essential part of modern health care, and electronic data capture (EDC) has become essential for managing clinical trials. Usually, these two entities are independent of each other, and transfer from one system to another is done manually. Our aim was to develop a method to capture data directly from the EHR system and transfer them into an EDC system for the NORwegian Disease-Modifying Anti-Rheumatic Drugs (NOR-DMARD) registry. All rheumatology departments contributing to NOR-DMARD had implemented a structured EHR system. Data are extracted locally and securely transferred to the study data management once a month. The study data management then parse the data into a readable format for the EDC and import the data. Once the data is in the EDC, they are available to all authorized researchers and downloadable in a preferred format. From May 2012 to August 2014 almost 6400 visits in 3400 patients treated with biologics have been successfully registered in the EDC system. Previously, NOR-DMARD used standard paper-based case report forms (CRFs), with a substantial cost for data entry. Setting up and maintaining the EDC system required some investments, but the amount saved from avoiding paper handling has made the shift into EDC profitable. In addition to this, gains have been made in administration and data quality. The transition from paper and pencil format to a fully electronic data management system in NOR-DMARD has had obvious advantages regarding feasibility, cost, data quality and accessibility of the data.

Cross sections of relativistic radiative electron capture by use of the strong-potential Born calculation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hino, K.; Watanabe, T.

1987-07-15

The relativistically extended strong-potential Born (SPB) formalism is applied to the radiative electron capture process caused by the bombardment of a heavy and highly stripped charged particle with relativistically high velocity. The results are compared with those by use of nonrelativistic SPB calculations and with those by use of the relativistic Born calculation (Sauter's formula), which includes no distortion effects between a heavy projectile ion and an active electron. Even if the strong distortion effects are taken into consideration, the shapes of photon angular distributions in the laboratory frame still nearly depend on sin/sup 2/theta/sub L/(theta/sub L/ is the anglemore » of the emitted photon) in the vicinity of the angle of 90/sup 0/, which is the same as the results by use of Sauter's formula. The higher the charge of a projectile ion becomes, however, the greater the discrepancy between the angular shape of our results and that of Sauter's becomes at both smaller and larger angles than at 90/sup 0/. As is expected, the magnitudes of the differential and the total cross sections are drastically influenced by the distortion effects ascribable to a large charge of a heavy projectile ion such as U/sup 92+/. Our results are in good agreement with recent experiments. In addition, the Coulomb off-shell factor introduced by the SPB theory is found playing important roles in the case of the relativistic radiative electron capture process because the results calculated by using the relativistic impulse approximation are too underestimated.« less

Toward a mechanistic modeling of nitrogen limitation on vegetation dynamics.

PubMed

Xu, Chonggang; Fisher, Rosie; Wullschleger, Stan D; Wilson, Cathy J; Cai, Michael; McDowell, Nate G

2012-01-01

Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO(2) concentration. To account for this known variability in nitrogen-photosynthesis relationships, we develop a mechanistic nitrogen allocation model based on a trade-off of nitrogen allocated between growth and storage, and an optimization of nitrogen allocated among light capture, electron transport, carboxylation, and respiration. The developed model is able to predict the acclimation of photosynthetic capacity to changes in CO(2) concentration, temperature, and radiation when evaluated against published data of V(c,max) (maximum carboxylation rate) and J(max) (maximum electron transport rate). A sensitivity analysis of the model for herbaceous plants, deciduous and evergreen trees implies that elevated CO(2) concentrations lead to lower allocation of nitrogen to carboxylation but higher allocation to storage. Higher growing-season temperatures cause lower allocation of nitrogen to carboxylation, due to higher nitrogen requirements for light capture pigments and for storage. Lower levels of radiation have a much stronger effect on allocation of nitrogen to carboxylation for herbaceous plants than for trees, resulting from higher nitrogen requirements for light capture for herbaceous plants. As far as we know, this is the first model of complete nitrogen allocation that simultaneously considers nitrogen allocation to light capture, electron transport, carboxylation, respiration and storage, and the responses of each to altered environmental conditions. We expect this model could potentially improve our confidence in simulations of carbon-nitrogen interactions and the vegetation feedbacks to climate in Earth system models.

Toward a Mechanistic Modeling of Nitrogen Limitation on Vegetation Dynamics

PubMed Central

Xu, Chonggang; Fisher, Rosie; Wullschleger, Stan D.; Wilson, Cathy J.; Cai, Michael; McDowell, Nate G.

2012-01-01

Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO2 concentration. To account for this known variability in nitrogen-photosynthesis relationships, we develop a mechanistic nitrogen allocation model based on a trade-off of nitrogen allocated between growth and storage, and an optimization of nitrogen allocated among light capture, electron transport, carboxylation, and respiration. The developed model is able to predict the acclimation of photosynthetic capacity to changes in CO2 concentration, temperature, and radiation when evaluated against published data of Vc,max (maximum carboxylation rate) and Jmax (maximum electron transport rate). A sensitivity analysis of the model for herbaceous plants, deciduous and evergreen trees implies that elevated CO2 concentrations lead to lower allocation of nitrogen to carboxylation but higher allocation to storage. Higher growing-season temperatures cause lower allocation of nitrogen to carboxylation, due to higher nitrogen requirements for light capture pigments and for storage. Lower levels of radiation have a much stronger effect on allocation of nitrogen to carboxylation for herbaceous plants than for trees, resulting from higher nitrogen requirements for light capture for herbaceous plants. As far as we know, this is the first model of complete nitrogen allocation that simultaneously considers nitrogen allocation to light capture, electron transport, carboxylation, respiration and storage, and the responses of each to altered environmental conditions. We expect this model could potentially improve our confidence in simulations of carbon-nitrogen interactions and the vegetation feedbacks to climate in Earth system models. PMID:22649564

Teaching Cellular Respiration & Alternate Energy Sources with a Laboratory Exercise Developed by a Scientist-Teacher Partnership

ERIC Educational Resources Information Center

Briggs, Brandon; Mitton, Teri; Smith, Rosemary; Magnuson, Timothy

2009-01-01

Microbial fuel cells are a current research area that harvests electricity from bacteria capable of anaerobic respiration. Graphite is an electrically conductive material that bacteria can respire on, thus it can be used to capture electrons from bacteria. When bacteria transfer electrons to graphite, an electrical potential is created that can…

School Security Solutions: Bringing Corporate Safety to Schools and Colleges with EasyLobbyTM Software.

ERIC Educational Resources Information Center

Pendzick, Richard E.; Downs, Robert L.

2002-01-01

Describes software for electronic visitor management (EVM) called EasyLobbyTM, currently in use in thousands of federal and corporate installations throughout the world and its application for school and campus environments. Explains EasyLobbyTM's use to replace visitor logs, capture and store visitor data electronically, and provide badges that…

On the origin of the electron blocking effect by an n-type AlGaN electron blocking layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Zi-Hui; Ji, Yun; Liu, Wei

2014-02-17

In this work, the origin of electron blocking effect of n-type Al{sub 0.25}Ga{sub 0.75}N electron blocking layer (EBL) for c+ InGaN/GaN light-emitting diodes has been investigated through dual-wavelength emission method. It is found that the strong polarization induced electric field within the n-EBL reduces the thermal velocity and correspondingly the mean free path of the hot electrons. As a result, the electron capture efficiency of the multiple quantum wells is enhanced, which significantly reduces the electron overflow from the active region and increases the radiative recombination rate with holes.

Electron self-injection in the donut bubble wakefield

NASA Astrophysics Data System (ADS)

Firouzjaei, Ali Shekari; Shokri, Babak

2018-05-01

We investigate electron self-injection in a donut bubble wakefield driven by a Laguerre-Gauss laser pulse. The present work discusses the electron capture by modeling the analytical donut bubble field. We discuss the self-injection of the electrons from plasma for various initial conditions and then compare the results. We show that the donut bubble can trap plasma electrons forming a hollow beam. We present the phase spaces and longitudinal momentum evolution for the trapped electrons in the bubble and discuss their characteristic behaviors and stability. It will be shown that the electrons self-injected in the front are ideal for applications in which a good stability and low energy spread are essential.

76 FR 55804 - Dicamba; Pesticide Tolerances

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-09

... Considerations A. Analytical Enforcement Methodology Adequate enforcement methodologies, Methods I and II--gas chromatography with electron capture detection (GC/ECD), are available to enforce the tolerance expression. The...

Borophene as a Promising Material for Charge-Modulated Switchable CO2 Capture.

PubMed

Tan, Xin; Tahini, Hassan A; Smith, Sean C

2017-06-14

Ideal carbon dioxide (CO 2 ) capture materials for practical applications should bind CO 2 molecules neither too weakly to limit good loading kinetics nor too strongly to limit facile release. Although charge-modulated switchable CO 2 capture has been proposed to be a controllable, highly selective, and reversible CO 2 capture strategy, the development of a practical gas-adsorbent material remains a great challenge. In this study, by means of density functional theory (DFT) calculations, we have examined the possibility of conductive borophene nanosheets as promising sorbent materials for charge-modulated switchable CO 2 capture. Our results reveal that the binding strength of CO 2 molecules on negatively charged borophene can be significantly enhanced by injecting extra electrons into the adsorbent. At saturation CO 2 capture coverage, the negatively charged borophene achieves CO 2 capture capacities up to 6.73 × 10 14 cm -2 . In contrast to the other CO 2 capture methods, the CO 2 capture/release processes on negatively charged borophene are reversible with fast kinetics and can be easily controlled via switching on/off the charges carried by borophene nanosheets. Moreover, these negatively charged borophene nanosheets are highly selective for separating CO 2 from mixtures with CH 4 , H 2 , and/or N 2 . This theoretical exploration will provide helpful guidance for identifying experimentally feasible, controllable, highly selective, and high-capacity CO 2 capture materials with ideal thermodynamics and reversibility.

Implementation of an electronic fingerprint-linked data collection system: a feasibility and acceptability study among Zambian female sex workers.

PubMed

Wall, Kristin M; Kilembe, William; Inambao, Mubiana; Chen, Yi No; Mchoongo, Mwaka; Kimaru, Linda; Hammond, Yuna Tiffany; Sharkey, Tyronza; Malama, Kalonde; Fulton, T Roice; Tran, Alex; Halumamba, Hanzunga; Anderson, Sarah; Kishore, Nishant; Sarwar, Shawn; Finnegan, Trisha; Mark, David; Allen, Susan A

2015-06-27

Patient identification within and between health services is an operational challenge in many resource-limited settings. When following HIV risk groups for service provision and in the context of vaccine trials, patient misidentification can harm patient care and bias trial outcomes. Electronic fingerprinting has been proposed to identify patients over time and link patient data between health services. The objective of this study was to determine 1) the feasibility of implementing an electronic-fingerprint linked data capture system in Zambia and 2) the acceptability of this system among a key HIV risk group: female sex workers (FSWs). Working with Biometrac, a US-based company providing biometric-linked healthcare platforms, an electronic fingerprint-linked data capture system was developed for use by field recruiters among Zambian FSWs. We evaluated the technical feasibility of the system for use in the field in Zambia and conducted a pilot study to determine the acceptability of the system, as well as barriers to uptake, among FSWs. We found that implementation of an electronic fingerprint-linked patient tracking and data collection system was feasible in this relatively resource-limited setting (false fingerprint matching rate of 1/1000 and false rejection rate of <1/10,000) and was acceptable among FSWs in a clinic setting (2% refusals). However, our data indicate that less than half of FSWs are comfortable providing an electronic fingerprint when recruited while they are working. The most common reasons cited for not providing a fingerprint (lack of privacy/confidentiality issues while at work, typically at bars or lodges) could be addressed by recruiting women during less busy hours, in their own homes, in the presence of "Queen Mothers" (FSW organizers), or in the presence of a FSW that has already been fingerprinted. Our findings have major implications for key population research and improved health services provision. However, more work needs to be done to increase the acceptability of the electronic fingerprint-linked data capture system during field recruitment. This study indicated several potential avenues that will be explored to increase acceptability.

Investigation of interface property in Al/SiO2/ n-SiC structure with thin gate oxide by illumination

NASA Astrophysics Data System (ADS)

Chang, P. K.; Hwu, J. G.

2017-04-01

The reverse tunneling current of Al/SiO2/ n-SiC structure employing thin gate oxide is introduced to examine the interface property by illumination. The gate current at negative bias decreases under blue LED illumination, yet increases under UV lamp illumination. Light-induced electrons captured by interface states may be emitted after the light sources are off, leading to the recovery of gate currents. Based on transient characteristics of gate current, the extracted trap level is close to the light energy for blue LED, indicating that electron capture induced by lighting may result in the reduction of gate current. Furthermore, bidirectional C- V measurements exhibit a positive voltage shift caused by electron trapping under blue LED illumination, while a negative voltage shift is observed under UV lamp illumination. Distinct trapping and detrapping behaviors can be observed from variations in I- V and C- V curves utilizing different light sources for 4H-SiC MOS capacitors with thin insulators.

Characteristics of a heavy water photoneutron source in boron neutron capture therapy

NASA Astrophysics Data System (ADS)

Danial, Salehi; Dariush, Sardari; M. Salehi, Jozani

2013-07-01

Bremsstrahlung photon beams produced by medical linear accelerators are currently the most commonly used method of radiation therapy for cancerous tumors. Photons with energies greater than 8-10 MeV potentially generate neutrons through photonuclear interactions in the accelerator's treatment head, patient's body, and treatment room ambient. Electrons impinging on a heavy target generate a cascade shower of bremsstrahlung photons, the energy spectrum of which shows an end point equal to the electron beam energy. By varying the target thickness, an optimum thickness exists for which, at the given electron energy, maximum photon flux is achievable. If a source of high-energy photons i.e. bremsstrahlung, is conveniently directed to a suitable D2O target, a novel approach for production of an acceptable flux of filterable photoneturons for boron neutron capture therapy (BNCT) application is possible. This study consists of two parts. 1. Comparison and assessment of deuterium photonuclear cross section data. 2. Evaluation of the heavy water photonuclear source.

Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector

PubMed Central

Field, Christopher R.; Lubrano, Adam; Woytowitz, Morgan; Giordano, Braden C.; Rose-Pehrsson, Susan L.

2014-01-01

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples. PMID:25145416

Quantitative detection of trace explosive vapors by programmed temperature desorption gas chromatography-electron capture detector.

PubMed

Field, Christopher R; Lubrano, Adam; Woytowitz, Morgan; Giordano, Braden C; Rose-Pehrsson, Susan L

2014-07-25

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples.

Weak-interaction rates in stellar conditions

NASA Astrophysics Data System (ADS)

Sarriguren, Pedro

2018-05-01

Weak-interaction rates, including β-decay and electron captures, are studied in several mass regions at various densities and temperatures of astrophysical interest. In particular, we study odd-A nuclei in the pf-shell region, which are involved in presupernova formations. Weak rates are relevant to understand the late stages of the stellar evolution, as well as the nucleosynthesis of heavy nuclei. The nuclear structure involved in the weak processes is studied within a quasiparticle proton-neutron random-phase approximation with residual interactions in both particle-hole and particle-particle channels on top of a deformed Skyrme Hartree-Fock mean field with pairing correlations. First, the energy distributions of the Gamow-Teller strength are discussed and compared with the available experimental information, measured under terrestrial conditions from charge-exchange reactions. Then, the sensitivity of the weak-interaction rates to both astrophysical densities and temperatures is studied. Special attention is paid to the relative contribution to these rates of thermally populated excited states in the decaying nucleus and to the electron captures from the degenerate electron plasma.

Electron capture by U(91+) and U(92+) and ionization of U(90+) and U(91+)

NASA Technical Reports Server (NTRS)

Gould, H.; Greiner, D.; Lindstrom, P.; Symons, T. J. M.; Crawford, H.

1984-01-01

U(92+)/U(91+) and U(91+)/U(90+) electron-capture and ionization cross sections and equilibrium charge-state distributions are measured experimentally in mylar, Cu and Ta of varying thickness. Relativistic U(68+) ions at 437 or 962 MeV/nucleon are produced by a heavy-ion linear accelerator and synchrotron in tandem and passed through the target material into a magnetic specrometer and position-sensitive proportional counter for evaluation of charge states. The results are presented graphically and discussed. At 962 MeV/nucleon, beams containing 85 percent bare U(92+) nuclei are obtained using 150-mg/sq cm Cu or 85-mg/sq cm Ta; at 437 MeV/nucleon, 50 percent bare U(92+) nuclei are obtained with 90-mg/sq cm Cu. The techniques decribed can be applied to produce beams of bare U nuclei for acceleration to ultrarelativistic speeds or beams of few-electron U for atomic-physics experiments on quantum electrodynamics.

Procurement of Shared Data Instruments for Research Electronic Data Capture (REDCap)

PubMed Central

Obeid, Jihad S; McGraw, Catherine A; Minor, Brenda L; Conde, José G; Pawluk, Robert; Lin, Michael; Wang, Janey; Banks, Sean R; Hemphill, Sheree A; Taylor, Rob; Harris, Paul A

2012-01-01

REDCap (Research Electronic Data Capture) is a web-based software solution and tool set that allows biomedical researchers to create secure online forms for data capture, management and analysis with minimal effort and training. The Shared Data Instrument Library (SDIL) is a relatively new component of REDCap that allows sharing of commonly used data collection instruments for immediate study use by 3 research teams. Objectives of the SDIL project include: 1) facilitating reuse of data dictionaries and reducing duplication of effort; 2) promoting the use of validated data collection instruments, data standards and best practices; and 3) promoting research collaboration and data sharing. Instruments submitted to the library are reviewed by a library oversight committee, with rotating membership from multiple institutions, which ensures quality, relevance and legality of shared instruments. The design allows researchers to download the instruments in a consumable electronic format in the REDCap environment. At the time of this writing, the SDIL contains over 128 data collection instruments. Over 2500 instances of instruments have been downloaded by researchers at multiple institutions. In this paper we describe the library platform, provide detail about experience gained during the first 25 months of sharing public domain instruments and provide evidence of impact for the SDIL across the REDCap consortium research community. We postulate that the shared library of instruments reduces the burden of adhering to sound data collection principles while promoting best practices. PMID:23149159

Strong-potential Born calculations for 1s-1s electron capture from atoms by protons

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGuire, J.H.; Kletke, R.E.; Sil, N.C.

1985-08-01

The strong-potential Born (SPB) approximation is examined by comparing various SPB calculations of high-velocity 1s-1s electron capture cross sections with one another and with experimental data. Above about 1 MeV, calculations using the SPB method of McGuire and Sil (SPMS) (Phys. Rev. A 28, 3679 (1983)) are in good agreement with total-cross-section observations for protons on H, He, C, Ne, and Ar as expected. For p+H and p+He, the SPB full-peaking (SPB-FP) approximation of Macek and Alston (Phys. Rev. A 26, 250 (1982)) and the SPB transverse-peaking (SPB-TP) approximation of Alston (Phys. Rev. A 27, 2342 (1982)) differ from ourmore » SPMS total cross sections by typically a factor of 2, as expected from general validity criteria. However, the differential cross sections at very forward angles (well within the Thomas angle) are the same in SPMS, SPB-FP, and SPB-TP methods in all cases. Below 1 MeV, cross sections obtained with use of various SPB methods differ considerably from one another, placing a limit of validity for these SPB calculations. We also suggest that in the gap between those energies where continuum intermediate states simply dominate, and above those energies where bound intermediate states simply dominate, detailed conceptual understanding of electron capture is incomplete.« less

Mechanistic Study on Electron Capture Dissociation of the Oligosaccharide-Mg2+ Complex

NASA Astrophysics Data System (ADS)

Huang, Yiqun; Pu, Yi; Yu, Xiang; Costello, Catherine E.; Lin, Cheng

2014-08-01

Electron capture dissociation (ECD) has shown great potential in structural characterization of glycans. However, our current understanding of the glycan ECD process is inadequate for accurate interpretation of the complex glycan ECD spectra. Here, we present the first comprehensive theoretical investigation on the ECD fragmentation behavior of metal-adducted glycans, using the cellobiose-Mg2+ complex as the model system. Molecular dynamics simulation was carried out to determine the typical glycan-Mg2+ binding patterns and the lowest-energy conformer identified was used as the initial geometry for density functional theory-based theoretical modeling. It was found that the electron is preferentially captured by Mg2+ and the resultant Mg+• can abstract a hydroxyl group from the glycan moiety to form a carbon radical. Subsequent radical migration and α-cleavage(s) result in the formation of a variety of product ions. The proposed hydroxyl abstraction mechanism correlates well with the major features in the ECD spectrum of the Mg2+-adducted cellohexaose. The mechanism presented here also predicts the presence of secondary, radical-induced fragmentation pathways. These secondary fragment ions could be misinterpreted, leading to erroneous structural determination. The present study highlights an urgent need for continuing investigation of the glycan ECD mechanism, which is imperative for successful development of bioinformatics tools that can take advantage of the rich structural information provided by ECD of metal-adducted glycans.

Dependence of weak interaction rates on the nuclear composition during stellar core collapse

NASA Astrophysics Data System (ADS)

Furusawa, Shun; Nagakura, Hiroki; Sumiyoshi, Kohsuke; Kato, Chinami; Yamada, Shoichi

2017-02-01

We investigate the influences of the nuclear composition on the weak interaction rates of heavy nuclei during the core collapse of massive stars. The nuclear abundances in nuclear statistical equilibrium (NSE) are calculated by some equation of state (EOS) models including in-medium effects on nuclear masses. We systematically examine the sensitivities of electron capture and neutrino-nucleus scattering on heavy nuclei to the nuclear shell effects and the single-nucleus approximation. We find that the washout of the shell effect at high temperatures brings significant change to weak rates by smoothing the nuclear abundance distribution: the electron capture rate decreases by ˜20 % in the early phase and increases by ˜40 % in the late phase at most, while the cross section for neutrino-nucleus scattering is reduced by ˜15 % . This is because the open-shell nuclei become abundant instead of those with closed neutron shells as the shell effects disappear. We also find that the single-nucleus description based on the average values leads to underestimations of weak rates. Electron captures and neutrino coherent scattering on heavy nuclei are reduced by ˜80 % in the early phase and by ˜5 % in the late phase, respectively. These results indicate that NSE like EOS accounting for shell washout is indispensable for the reliable estimation of weak interaction rates in simulations of core-collapse supernovae.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shao, Tao, E-mail: st@mail.iee.ac.cn; Yang, Wenjin; Zhang, Cheng

Polymer materials, such as polymethylmethacrylate (PMMA), are widely used as insulators in vacuum. The insulating performance of a high-voltage vacuum system is mainly limited by surface flashover of the insulators rather than bulk breakdown. Non-thermal plasmas are an efficient method to modify the chemical and physical properties of polymer material surfaces, and enhance the surface insulating performance. In this letter, an atmospheric-pressure dielectric barrier discharge is used to treat the PMMA surface to improve the surface flashover strength in vacuum. Experimental results indicate that the plasma treatment method using Ar and CF{sub 4} (10:1) as the working gas can etchmore » the PMMA surface, introduce fluoride groups to the surface, and then alter the surface characteristics of the PMMA. The increase in the surface roughness can introduce physical traps that can capture free electrons, and the fluorination can enhance the charge capturing ability. The increase in the surface roughness and the introduction of the fluoride groups can enhance the PMMA hydrophobic ability, improve the charge capturing ability, decrease the secondary electron emission yield, increase the surface resistance, and improve the surface flashover voltage in vacuum.« less

Capture, acceleration and bunching rf systems for the MEIC booster and storage rings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Shaoheng; Guo, Jiquan; Lin, Fanglei

2015-09-01

The Medium-energy Electron Ion Collider (MEIC), proposed by Jefferson Lab, consists of a series of accelerators. The electron collider ring accepts electrons from CEBAF at energies from 3 to 12 GeV. Protons and ions are delivered to a booster and captured in a long bunch before being ramped and transferred to the ion collider ring. The ion collider ring accelerates a small number of long ion bunches to colliding energy before they are re-bunched into a high frequency train of very short bunches for colliding. Two sets of low frequency RF systems are needed for the long ion bunch energymore » ramping in the booster and ion collider ring. Another two sets of high frequency RF cavities are needed for re-bunching in the ion collider ring and compensating synchrotron radiation energy loss in the electron collider ring. The requirements from energy ramping, ion beam bunching, electron beam energy compensation, collective effects, beam loading and feedback capability, RF power capability, etc. are presented. The preliminary designs of these RF systems are presented. Concepts for the baseline cavity and RF station configurations are described, as well as some options that may allow more flexible injection and acceleration schemes.« less

Hybrid data capture for monitoring patients on highly active antiretroviral therapy (HAART) in urban Botswana.

PubMed

Bussmann, Hermann; Wester, C William; Ndwapi, Ndwapi; Vanderwarker, Chris; Gaolathe, Tendani; Tirelo, Geoffrey; Avalos, Ava; Moffat, Howard; Marlink, Richard G

2006-02-01

Individual patient care and programme evaluation are pivotal for the success of antiretroviral treatment programmes in resource-limited countries. While computer-aided documentation and data storage are indispensable for any large programme, several important issues need to be addressed including which data are to be collected, who collects it and how it is entered into an electronic database. We describe a patient-monitoring approach, which uses patient encounter forms (in hybrid paper + electronic format) based on optical character recognition, piloted at Princess Marina Hospital in Gaborone, Botswana's first public highly active antiretroviral therapy (HAART) outpatient clinic. Our novel data capture approach collects "key" data for tracking patient and programme outcomes. It saves physician time and does not detract from clinical care.

The origin of the Crab Nebula and the electron capture supernova in 8-10 M solar mass stars

NASA Technical Reports Server (NTRS)

Nomoto, K.

1981-01-01

The chemical composition of the Crab Nebula is compared with several presupernova models. The small carbon and oxygen abundances in the helium-rich nebula are consistent with only the presupernova model of the star whose main sequence mass was MMS approximately 8-9.5 M. More massive stars contain too much carbon in the helium layer and smaller mass stars do not leave neutron stars. The progenitor star of the Crab Nebula lost appreciable part of the hydrogen-rich envelope before the hydrogen-rich and helium layers were mixed by convection. Finally it exploded as the electron capture supernova; the O+Ne+Mg core collapsed to form a neutron star and only the extended helium-rich envelope was ejected by the weak shock wave.

Simultaneous determination of chlorinated organic compounds from environmental samples using gas chromatography coupled with a micro electron capture detector and micro-plasma atomic emission detector

NASA Astrophysics Data System (ADS)

Quan, Xie; Chen, Shuo; Platzer, Bernhard; Chen, Jingwen; Gfrerer, Marion

2002-01-01

Water and sediment samples were screened simultaneously for the presence of polychlorinated organic compounds using gas chromatography (GC) coupled with an micro electron capture detector (μ-ECD) and a newly developed helium plasma based on a micro-atomic emission detector (μ-AED). The GC column effluent was split 15:85 between two detectors. In this way, two chromatograms, one obtained by μ-ECD and another by μ-AED, were recorded simultaneously. α-, β-hexachlorocyclohexane and p, p'-DDE were detected. RSDs of the monitoring results from the two detection methods were <20% for the three compounds. A detection limit of 8.5 pg and at least 3 orders of magnitude of linear range for μ-AED was observed.

A Foundation for Enterprise Imaging: HIMSS-SIIM Collaborative White Paper.

PubMed

Roth, Christopher J; Lannum, Louis M; Persons, Kenneth R

2016-10-01

Care providers today routinely obtain valuable clinical multimedia with mobile devices, scope cameras, ultrasound, and many other modalities at the point of care. Image capture and storage workflows may be heterogeneous across an enterprise, and as a result, they often are not well incorporated in the electronic health record. Enterprise Imaging refers to a set of strategies, initiatives, and workflows implemented across a healthcare enterprise to consistently and optimally capture, index, manage, store, distribute, view, exchange, and analyze all clinical imaging and multimedia content to enhance the electronic health record. This paper is intended to introduce Enterprise Imaging as an important initiative to clinical and informatics leadership, and outline its key elements of governance, strategy, infrastructure, common multimedia content, acquisition workflows, enterprise image viewers, and image exchange services.

Hybrid data capture for monitoring patients on highly active antiretroviral therapy (HAART) in urban Botswana.

PubMed Central

Bussmann, Hermann; Wester, C. William; Ndwapi, Ndwapi; Vanderwarker, Chris; Gaolathe, Tendani; Tirelo, Geoffrey; Avalos, Ava; Moffat, Howard; Marlink, Richard G.

2006-01-01

Individual patient care and programme evaluation are pivotal for the success of antiretroviral treatment programmes in resource-limited countries. While computer-aided documentation and data storage are indispensable for any large programme, several important issues need to be addressed including which data are to be collected, who collects it and how it is entered into an electronic database. We describe a patient-monitoring approach, which uses patient encounter forms (in hybrid paper + electronic format) based on optical character recognition, piloted at Princess Marina Hospital in Gaborone, Botswana's first public highly active antiretroviral therapy (HAART) outpatient clinic. Our novel data capture approach collects "key" data for tracking patient and programme outcomes. It saves physician time and does not detract from clinical care. PMID:16501730

Orbital Electron Capture Rates in Extreme Astrophysical Environments

NASA Astrophysics Data System (ADS)

Martin, Matthew; McDonald, William; Leach, Kyle

2017-09-01

In an attempt to better understand EC decay rates in hot environments, we have developed a program to examine and parse all evaluated atomic and nuclear data. Taking into account the effects of ionization on accessible decay states and electron capture probabilities, half lives across the nuclear chart can be investigated without the need for theoretical estimates. Part of the ongoing project will include isolating stable isotopes that become unstable due to ionization and estimating their stability in these new environments. In addition, we hope to account for a thermal population of excited states to better simulate these environments. This should aide in the complete understanding of nuclear processes in these extreme astrophysical environments. This work is supported in part by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics.

Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

PubMed Central

Swierk, John R.; Méndez-Hernández, Dalvin D.; McCool, Nicholas S.; Liddell, Paul; Terazono, Yuichi; Pahk, Ian; Tomlin, John J.; Oster, Nolan V.; Moore, Thomas A.; Moore, Ana L.; Gust, Devens; Mallouk, Thomas E.

2015-01-01

Solar fuel generation requires the efficient capture and conversion of visible light. In both natural and artificial systems, molecular sensitizers can be tuned to capture, convert, and transfer visible light energy. We demonstrate that a series of metal-free porphyrins can drive photoelectrochemical water splitting under broadband and red light (λ > 590 nm) illumination in a dye-sensitized TiO2 solar cell. We report the synthesis, spectral, and electrochemical properties of the sensitizers. Despite slow recombination of photoinjected electrons with oxidized porphyrins, photocurrents are low because of low injection yields and slow electron self-exchange between oxidized porphyrins. The free-base porphyrins are stable under conditions of water photoelectrolysis and in some cases photovoltages in excess of 1 V are observed. PMID:25583488

Hematopoietic stem cell capture and directional differentiation into vascular endothelial cells for metal stent-coated chitosan/hyaluronic acid loading CD133 antibody.

PubMed

Zhang, Shixuan; Zhang, Fan; Feng, Bo; Fan, Qingyu; Yang, Feng; Shang, Debin; Sui, Jinghan; Zhao, Hong

2015-03-01

A series of metal stents coated with chitosan/hyaluronic acid (CS/HA) loading antibodies by electrostatic self-assembled method were prepared, and the types of cells captured by antibodies and their differentiation in vascular endothelial cells (ECs) evaluated by molecular biology and scanning electron microscope. The results showed that CD133 stent can selectively capture hematopoietic stem cells (HSC),which directionally differentiate into vascular ECs in peripheral blood by (CS/HA) induction, and simultaneously inhibit migration and proliferation of immune cells and vascular smooth muscle cells (MCs). CD34 stent can capture HSC, hematopoietic progenitor cells that differentiate into vascular ECs and immune cells, promoting smooth MCs growth, leading to thrombosis, inflammation, and rejection. CD133 stent can be implanted into miniature pig heart coronary and can repair vascular damage by capturing own HSC, thus contributing to the rapid natural vascular repair, avoiding inflammation and rejection, thrombosis and restenosis. These studies demonstrated that CD133 stent of HSC capture will be an ideal coated metal stent providing a new therapeutic approach for cardiovascular and cerebrovascular disease.

Stopping of protons - Improved accuracy of the UCA model

NASA Astrophysics Data System (ADS)

Schiwietz, G.; Grande, P. L.

2012-02-01

Recent theoretical developments in the unitary convolution approximation (UCA) for electronic energy losses of bare and screened ions are presented. Examples are given for proton beams and rare-gas targets. For gas targets there exists a sufficient amount of experimental data on charge exchange, for pinpointing the largely unknown stopping-power contribution of electron-capture processes at low and intermediate energies.

Top-Down Hydrogen-Deuterium Exchange Analysis of Protein Structures Using Ultraviolet Photodissociation.

PubMed

Brodie, Nicholas I; Huguet, Romain; Zhang, Terry; Viner, Rosa; Zabrouskov, Vlad; Pan, Jingxi; Petrotchenko, Evgeniy V; Borchers, Christoph H

2018-03-06

Top-down hydrogen-deuterium exchange (HDX) analysis using electron capture or transfer dissociation Fourier transform mass spectrometry (FTMS) is a powerful method for the analysis of secondary structure of proteins in solution. The resolution of the method is a function of the degree of fragmentation of backbone bonds in the proteins. While fragmentation is usually extensive near the N- and C-termini, electron capture (ECD) or electron transfer dissociation (ETD) fragmentation methods sometimes lack good coverage of certain regions of the protein, most often in the middle of the sequence. Ultraviolet photodissociation (UVPD) is a recently developed fast-fragmentation technique, which provides extensive backbone fragmentation that can be complementary in sequence coverage to the aforementioned electron-based fragmentation techniques. Here, we explore the application of electrospray ionization (ESI)-UVPD FTMS on an Orbitrap Fusion Lumos Tribrid mass spectrometer to top-down HDX analysis of proteins. We have incorporated UVPD-specific fragment-ion types and fragment-ion mixtures into our isotopic envelope fitting software (HDX Match) for the top-down HDX analysis. We have shown that UVPD data is complementary to ETD, thus improving the overall resolution when used as a combined approach.

42 CFR 456.722 - Electronic claims management system.

Code of Federal Regulations, 2011 CFR

2011-10-01

... verifications, claims data capture, adjudication of claims, and to assist pharmacists and other authorized... pharmacist (or other authorized person, such as the dispensing physician) about the claim status. (iii...

42 CFR 456.722 - Electronic claims management system.

Code of Federal Regulations, 2010 CFR

2010-10-01

... verifications, claims data capture, adjudication of claims, and to assist pharmacists and other authorized... pharmacist (or other authorized person, such as the dispensing physician) about the claim status. (iii...

42 CFR 456.722 - Electronic claims management system.

Code of Federal Regulations, 2014 CFR

2014-10-01

... verifications, claims data capture, adjudication of claims, and to assist pharmacists and other authorized...) Notifying the pharmacist (or other authorized person, such as the dispensing physician) about the claim...

42 CFR 456.722 - Electronic claims management system.

Code of Federal Regulations, 2012 CFR

2012-10-01

... verifications, claims data capture, adjudication of claims, and to assist pharmacists and other authorized...) Notifying the pharmacist (or other authorized person, such as the dispensing physician) about the claim...

42 CFR 456.722 - Electronic claims management system.

Code of Federal Regulations, 2013 CFR

2013-10-01

... verifications, claims data capture, adjudication of claims, and to assist pharmacists and other authorized...) Notifying the pharmacist (or other authorized person, such as the dispensing physician) about the claim...

Astronaut Kathryn Thornton on HST photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-05

S61-E-011 (5 Dec 1993) --- This view of astronaut Kathryn C. Thornton working on the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. Thornton, anchored to the end of the Remote Manipulator System (RMS) arm, is installing the +V2 Solar Array Panel as a replacement for the original one removed earlier. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Diversity of abundance patterns of neutron-capture elements in very metal-poor stars

NASA Astrophysics Data System (ADS)

Aoki, Misa; Aoki, Wako; Ishimaru, Yuhri; Wanajo, Shinya

2014-05-01

Observations of Very Metal-Poor stars indicate that there are at least two sites to r-process; "weak r-process" and "main r-process". A question is whether these two are well separated or there exists a variation in the r-process. We present the results of abundance analysis of neutron-capture elements in the two Very Metal-Poor stars HD107752 and HD110184 in the Milky Way halo observed with the Subaru Telescope HDS. The abundance patterns show overabundace at light n-capture elements (e.g. Sr, Y), inferring the element yielding of weak r-process, while heavy neutron-capture elements (e.g. Ba, Eu) are deficient; however, the overabundance of light ones is not as significant as that previously found in stars representing the weak r-process (e.g. HD122563; Honda et al. 2006). Our study show diversity in the abundance patterns from light to heavy neutron-capture elements in VMP stars, suggesting a variation in r-process, which may depend on electron fraction of environment.

Improving Performance on Preventive Health Quality Measures Using Clinical Decision Support to Capture Care Done Elsewhere and Patient Exceptions.

PubMed

Bowen, Michael E; Bhat, Deepa; Fish, Jason; Moran, Brett; Howell-Stampley, Temple; Kirk, Lynne; Persell, Stephen D; Halm, Ethan A

Preventive services required for performance measurement often are completed in outside health systems and not captured in electronic medical records (EMRs). A before-after study was conducted to examine the ability of clinical decision support (CDS) to improve performance on preventive quality measures, capture clinician-reported services completed elsewhere, and patient/medical exceptions and to describe their impact on quality measurement. CDS improved performance on colorectal cancer screening, osteoporosis screening, and pneumococcal vaccination measures ( P < .05) but not breast or cervical cancer screening. CDS captured clinician-reported services completed elsewhere (2% to 10%) and patient/medical exceptions (<3%). Compared to measures using only within-system data, including services completed elsewhere in the numerator improved performance: pneumococcal vaccine (73% vs 82%); breast (69% vs 75%), colorectal (58% vs 70%), and cervical cancer (53% vs 62%); and osteoporosis (72% vs 75%) screening ( P < .05). Visit-based CDS can capture clinician-reported preventive services, and accounting for services completed elsewhere improves performance on quality measures.

Surface modification of a low cost bentonite for post-combustion CO2 capture

NASA Astrophysics Data System (ADS)

Chen, Chao; Park, Dong-Wha; Ahn, Wha-Seung

2013-10-01

A low cost bentonite was modified with PEI (polyethylenimine) through a physical impregnation method. Bentonite in its natural state and after amine modification were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, N2 adsorption-desorption isotherms, and investigated for CO2 capture using a thermogravimetric analysis unit connected to a flow panel. The effect of adsorption temperature, PEI loading and CO2 partial pressure on the CO2 capture performance of the PEI-modified bentonite was examined. A cyclic CO2 adsorption-desorption test was also carried out to assess the stability of PEI-modified bentonite as a CO2 adsorbent. Bentonite in its natural state showed negligible CO2 uptake. After amine modification, the CO2 uptake increased significantly due to CO2 capture by amine species introduced via chemisorption. The PEI-modified bentonites showed high CO2 capture selectivity over N2, and exhibited excellent stability in cyclic CO2 adsorption-desorption runs.

A spherical electron cloud hopping model for studying product branching ratios of dissociative recombination.

PubMed

Yu, Hua-Gen

2008-05-21

A spherical electron cloud hopping (SECH) model is proposed to study the product branching ratios of dissociative recombination (DR) of polyatomic systems. In this model, the fast electron-captured process is treated as an instantaneous hopping of a cloud of uniform spherical fractional point charges onto a target M+q ion (or molecule). The sum of point charges (-1) simulates the incident electron. The sphere radius is determined by a critical distance (Rc eM) between the incoming electron (e-) and the target, at which the potential energy of the e(-)-M+q system is equal to that of the electron-captured molecule M+q(-1) in a symmetry-allowed electronic state with the same structure as M(+q). During the hopping procedure, the excess energies of electron association reaction are dispersed in the kinetic energies of M+q(-1) atoms to conserve total energy. The kinetic energies are adjusted by linearly adding atomic momenta in the direction of driving forces induced by the scattering electron. The nuclear dynamics of the resultant M+q(-1) molecule are studied by using a direct ab initio dynamics method on the adiabatic potential energy surface of M+q(-1), or together with extra adiabatic surface(s) of M+q(-1). For the latter case, the "fewest switches" surface hopping algorithm of Tully was adapted to deal with the nonadiabaticity in trajectory propagations. The SECH model has been applied to study the DR of both CH+ and H3O+(H2O)2. The theoretical results are consistent with the experiment. It was found that water molecules play an important role in determining the product branching ratios of the molecular cluster ion.

Terrestrial Clay under Microscope

NASA Image and Video Library

2008-09-30

A scanning electron microscope captured this image of terresterial soil containing a phyllosilicate mineral from Koua Bocca, Ivory Coast, West Africa. This soil shares some similarities with Martian soil scooped by NASA Phoenix Lander.

Asymmetry and Electronegativity in the Electron Capture Activation of the Se-Se Bond: σ*(Se-Se) vs σ*(Se-X).

PubMed

Gámez, José A; Yáñez, Manuel

2010-10-12

The effects of electron capture on the structure of XSeSeX' diselenide derivatives in which the substituents attached to the selenium atoms have different electronegativities have been investigated at different levels of theory, namely, DFT, MP2, CCSD, G2, and CASSCF/CASPT2. An analysis of the bonding changes upon electron attachment shows that when the diselenides bear low-electronegativity substituents, the Se-Se bond becomes activated upon electron capture, as previous studies have shown. However, this is no longer the case for very electronegative substituents, where this bond remains practically unaltered and is the Se-X bond the one which becomes strongly activated through a preferential population of the σ*(Se-X) antibonding orbital rather than the σ*(Se-Se) one. When this is the case, several anionic species are also encountered, namely, stretched, bent, and book structures. The present findings are similar to those obtained for a series of analogous disulfide compounds, which points out that these results are not unique and could be extrapolated to a wider range of compounds than the ones covered here. The Se-Se (Se-X) linkage in CH3SeSeOH, CH3SeSeF, FSeSeOH, and FSeSeF bears some of the characteristics of the so-called charge-shift bonds, with a clear charge fluctuation between both selenium atoms. This is more evident in their anions where the bonding reflects the important contribution of the ionic resonant forms Se-Se(-) ↔ (-)Se-Se vs the covalent component Se∴Se. This resonance changes with the nature of the substituents but also depends on the asymmetry of the substitution.

Collective Poisson process with periodic rates: applications in physics from micro-to nanodevices.

PubMed

da Silva, Roberto; Lamb, Luis C; Wirth, Gilson Inacio

2011-01-28

Continuous reductions in the dimensions of semiconductor devices have led to an increasing number of noise sources, including random telegraph signals (RTS) due to the capture and emission of electrons by traps at random positions between oxide and semiconductor. The models traditionally used for microscopic devices become of limited validity in nano- and mesoscale systems since, in such systems, distributed quantities such as electron and trap densities, and concepts like electron mobility, become inadequate to model electrical behaviour. In addition, current experimental works have shown that RTS in semiconductor devices based on carbon nanotubes lead to giant current fluctuations. Therefore, the physics of this phenomenon and techniques to decrease the amplitudes of RTS need to be better understood. This problem can be described as a collective Poisson process under different, but time-independent, rates, τ(c) and τ(e), that control the capture and emission of electrons by traps distributed over the oxide. Thus, models that consider calculations performed under time-dependent periodic capture and emission rates should be of interest in order to model more efficient devices. We show a complete theoretical description of a model that is capable of showing a noise reduction of current fluctuations in the time domain, and a reduction of the power spectral density in the frequency domain, in semiconductor devices as predicted by previous experimental work. We do so through numerical integrations and a novel Monte Carlo Markov chain (MCMC) algorithm based on microscopic discrete values. The proposed model also handles the ballistic regime, relevant in nano- and mesoscale devices. Finally, we show that the ballistic regime leads to nonlinearity in the electrical behaviour.

Support and Assessment for Fall Emergency Referrals (SAFER 1): Cluster Randomised Trial of Computerised Clinical Decision Support for Paramedics

PubMed Central

Snooks, Helen Anne; Carter, Ben; Dale, Jeremy; Foster, Theresa; Humphreys, Ioan; Logan, Philippa Anne; Lyons, Ronan Anthony; Mason, Suzanne Margaret; Phillips, Ceri James; Sanchez, Antonio; Wani, Mushtaq; Watkins, Alan; Wells, Bridget Elizabeth; Whitfield, Richard; Russell, Ian Trevor

2014-01-01

Objective To evaluate effectiveness, safety and cost-effectiveness of Computerised Clinical Decision Support (CCDS) for paramedics attending older people who fall. Design Cluster trial randomised by paramedic; modelling. Setting 13 ambulance stations in two UK emergency ambulance services. Participants 42 of 409 eligible paramedics, who attended 779 older patients for a reported fall. Interventions Intervention paramedics received CCDS on Tablet computers to guide patient care. Control paramedics provided care as usual. One service had already installed electronic data capture. Main Outcome Measures Effectiveness: patients referred to falls service, patient reported quality of life and satisfaction, processes of care. Safety Further emergency contacts or death within one month. Cost-Effectiveness Costs and quality of life. We used findings from published Community Falls Prevention Trial to model cost-effectiveness. Results 17 intervention paramedics used CCDS for 54 (12.4%) of 436 participants. They referred 42 (9.6%) to falls services, compared with 17 (5.0%) of 343 participants seen by 19 control paramedics [Odds ratio (OR) 2.04, 95% CI 1.12 to 3.72]. No adverse events were related to the intervention. Non-significant differences between groups included: subsequent emergency contacts (34.6% versus 29.1%; OR 1.27, 95% CI 0.93 to 1.72); quality of life (mean SF12 differences: MCS −0.74, 95% CI −2.83 to +1.28; PCS −0.13, 95% CI −1.65 to +1.39) and non-conveyance (42.0% versus 36.7%; OR 1.13, 95% CI 0.84 to 1.52). However ambulance job cycle time was 8.9 minutes longer for intervention patients (95% CI 2.3 to 15.3). Average net cost of implementing CCDS was £208 per patient with existing electronic data capture, and £308 without. Modelling estimated cost per quality-adjusted life-year at £15,000 with existing electronic data capture; and £22,200 without. Conclusions Intervention paramedics referred twice as many participants to falls services with no difference in safety. CCDS is potentially cost-effective, especially with existing electronic data capture. Trial Registration ISRCTN Register ISRCTN10538608 PMID:25216281

Enhanced photocatalytic activity of Te-doped Bi{sub 2}MoO{sub 6} under visible light irradiation: Effective separation of photogenerated carriers resulted from inhomogeneous lattice distortion and improved electron capturing ability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Shuguang, E-mail: csustcsg@yahoo.com; Li, Yuhan; Wu, Zixu

Te-doped Bi{sub 2}MoO{sub 6} photocatalyst was hydrothermally synthesized, and nonmetal atoms Te were homogeneously incorporated into Bi{sub 2}MoO{sub 6} lattice with the substitution of Te{sup 4+} to Mo{sup 6+}. With increasing Te-doping concentration in Bi{sub 2}MoO{sub 6}, no detectable band-gap narrowing but more and more severe inhomogeneous lattice distortions were determined. The activity of Bi{sub 2}MoO{sub 6} photocatalyst was evaluated through methylene blue degradation under visible light irradiation (λ>410 nm) and was greatly enhanced by Te-doping. When Te-doped Bi{sub 2}MoO{sub 6} was synthesized at Te/Mo molar ratio of 7.5%, a maximum first-order rate constant of methylene blue degradation was obtained.more » The inhomogeneous lattice distortion generated an internal dipole moment, and the holes generated with the substitution of Te{sup 4+} to Mo{sup 6+} acted as the capturing centers of photogenerated electrons, thus the effective separation of photogenerated carriers was facilitated to result in a relatively high concentration of holes on the surface of Te-doped Bi{sub 2}MoO{sub 6} to be favorable for the efficient methylene blue degradation. - Graphical abstract: With the substitution of Te{sup 4+} to Mo{sup 6+}, effective separation of photogenerated carriers resulted from inhomogeneous lattice distortion and improved electron capturing ability is achieved to be responsible for enhanced photocatalytic activity of Te-doped Bi{sub 2}MoO{sub 6}. - Highlights: • Nonmetal Te is incorporated into Bi{sub 2}MoO{sub 6} with the substitution of Te{sup 4+} to Mo{sup 6+}. • Revealing inhomogeneous lattice distortion and improved electron capturing ability. • Effective separation of photogenerated carriers in Te-doped Bi{sub 2}MoO{sub 6} is achieved. • The mechanism of methylene blue degradation over Te-doped Bi{sub 2}MoO{sub 6} is proposed.« less

Many-body formulation of carriers capture time in quantum dots applicable in device simulation codes

NASA Astrophysics Data System (ADS)

Vallone, Marco

2010-03-01

We present an application of Green's functions formalism to calculate in a simplified but rigorous way electrons and holes capture time in quantum dots in closed form as function of carrier density, levels confinement potential, and temperature. Carrier-carrier (Auger) scattering and single LO-phonon emission are both addressed accounting for dynamic effects of the potential screening in the single plasmon pole approximation of the dielectric function. Regarding the LO-phonons interaction, the formulation evidences the role of the dynamic screening from wetting-layer carriers in comparison with its static limit, describes the interplay between screening and Fermi band filling, and offers simple expressions for capture time, suitable for modeling implementation.

Ab initio investigation of electron capture by Cl{sup 7+} ions from H

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, L. B.; Stancil, P. C.; Watanabe, A.

2007-08-15

An investigation of charge transfer in collisions of ground-state Cl{sup 7+} with H has been conducted based on a fully quantum-mechanical molecular-orbital close-coupling (QMOCC) approach. The charge-transfer process Cl{sup 7+}({sup 1}S)+H{yields}Cl{sup 6+}(2p{sup 6}nl {sup 2}S,{sup 2}P{sup o},{sup 2}D,{sup 2}F{sup o},{sup 2}G)+H{sup +} with n=5 and 6 is taken into account for collision energies between 10{sup -4} eV/u and 1 keV/u. The relevant adiabatic potentials and nonadiabatic coupling matrix elements for the ClH{sup 7+} system are evaluated with the configuration-interaction method. The investigation shows that electron capture into the 5d, 5f, 5g, and 6p states dominates for collision energies less thanmore » {approx}1 eV/u, while above 100 eV/u the 5s, 5p, 5d, and 6p are the primary capture channels. Comparison with experimental data for collisions of Cl{sup 7+}({sup 1}S) with D reveals a discrepancy over the full range of measured energies (5-430 eV/u), while no significant isotope effect is found for QMOCC calculations with deuterium. Furthermore, comparison with a previous calculation of the one-electron N{sup 7+}+H system, as well as measurements of the multielectron Al{sup 7+}+H and Fe{sup 7+}+H systems, suggests that the electronic structure of the core has a non-negligible effect on the charge-transfer process. A one-electron model for relative l distributions is found to agree with the QMOCC results for n=5 between 100 and 1000 eV/u, but fails at lower collision energies. Finally, state-selective and total rate coefficients are given for temperatures between 10 and 200 000 K.« less

Glow discharge detector

DOEpatents

Koo, Jackson C.; Yu, Conrad M.

2002-01-01

A highly sensitive electronic ion cell for the measurement of trace elements in He carrier gas which involves glow discharge. A constant wave (CW) glow discharge detector which is controlled through a biased resistor, can detect the change of electron density caused by impurities in the He carrier gas by many orders of magnitude larger than that caused by direct ionization or electron capture. The glow discharge detector utilizes a floating pseudo-electrode to form a probe in or near the plasma. By using this probe, the large variation of electron density due to trace amounts of impurities can be directly measured.

Concurrent engineering design and management knowledge capture

NASA Technical Reports Server (NTRS)

1990-01-01

The topics are presented in viewgraph form and include the following: real-time management, personnel management, project management, conceptual design and decision making; the SITRF design problem; and the electronic-design notebook.

Relativistic Photoionization Computations with the Time Dependent Dirac Equation

DTIC Science & Technology

2016-10-12

fields often occurs in the relativistic regime. A complete description of this phenomenon requires both relativistic and quantum mechanical treatment...photoionization, or other relativis- tic quantum electronics problems. While the Klein-Gordon equation captures much of the relevant physics, especially...for moderately heavy ions (Z 137), it does neglect the spin polarization of the electron. This memo parallels [1], but replaces the Klein-Gordon

Inelastic electron injection in a water chain

PubMed Central

Rizzi, Valerio; Todorov, Tchavdar N.; Kohanoff, Jorge J.

2017-01-01

Irradiation of biological matter triggers a cascade of secondary particles that interact with their surroundings, resulting in damage. Low-energy electrons are one of the main secondary species and electron-phonon interaction plays a fundamental role in their dynamics. We have developed a method to capture the electron-phonon inelastic energy exchange in real time and have used it to inject electrons into a simple system that models a biological environment, a water chain. We simulated both an incoming electron pulse and a steady stream of electrons and found that electrons with energies just outside bands of excited molecular states can enter the chain through phonon emission or absorption. Furthermore, this phonon-assisted dynamical behaviour shows great sensitivity to the vibrational temperature, highlighting a crucial controlling factor for the injection and propagation of electrons in water. PMID:28350013

Surface hopping with a manifold of electronic states. III. Transients, broadening, and the Marcus picture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dou, Wenjie; Subotnik, Joseph E.; Nitzan, Abraham

2015-06-21

In a previous paper [Dou et al., J. Chem. Phys. 142, 084110 (2015)], we have introduced a surface hopping (SH) approach to deal with the Anderson-Holstein model. Here, we address some interesting aspects that have not been discussed previously, including transient phenomena and extensions to arbitrary impurity-bath couplings. In particular, in this paper we show that the SH approach captures phonon coherence beyond the secular approximation, and that SH rates agree with Marcus theory at steady state. Finally, we show that, in cases where the electronic tunneling rate depends on nuclear position, a straightforward use of Marcus theory rates yieldsmore » a useful starting point for capturing level broadening. For a simple such model, we find I-V curves that exhibit negative differential resistance.« less

Towards saturation of the electron-capture delayed fission probability: The new isotopes 240Es and 236Bk

NASA Astrophysics Data System (ADS)

Konki, J.; Khuyagbaatar, J.; Uusitalo, J.; Greenlees, P. T.; Auranen, K.; Badran, H.; Block, M.; Briselet, R.; Cox, D. M.; Dasgupta, M.; Di Nitto, A.; Düllmann, Ch. E.; Grahn, T.; Hauschild, K.; Herzán, A.; Herzberg, R.-D.; Heßberger, F. P.; Hinde, D. J.; Julin, R.; Juutinen, S.; Jäger, E.; Kindler, B.; Krier, J.; Leino, M.; Lommel, B.; Lopez-Martens, A.; Luong, D. H.; Mallaburn, M.; Nishio, K.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Peura, P.; Rahkila, P.; Rezynkina, K.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Sorri, J.; Stolze, S.; Sulignano, B.; Theisen, Ch.; Ward, A.; Yakushev, A.; Yakusheva, V.

2017-01-01

The new neutron-deficient nuclei 240Es and 236Bk were synthesised at the gas-filled recoil separator RITU. They were identified by their radioactive decay chains starting from 240Es produced in the fusion-evaporation reaction 209Bi(34S,3n)240Es. Half-lives of 6 (2)s and 22-6+13s were obtained for 240Es and 236Bk, respectively. Two groups of α particles with energies Eα = 8.19 (3)MeV and 8.09 (3)MeV were unambiguously assigned to 240Es. Electron-capture delayed fission branches with probabilities of 0.16 (6) and 0.04 (2) were measured for 240Es and 236Bk, respectively. These new data show a continuation of the exponential increase of ECDF probabilities in more neutron-deficient isotopes.

Simultaneous multi-state stimulated emission in quantum dot lasers: experiment and analytical approach

NASA Astrophysics Data System (ADS)

Korenev, V. V.; Savelyev, A. V.; Zhukov, A. E.; Omelchenko, A. V.; Maximov, M. V.; Shernyakov, Yu. M.

2012-06-01

The theoretical investigation of the double-state lasing phenomena in InAs/InGaAs quantum dot lasers has been carried out. The new mechanism of the ground-state lasing quenching, which takes place in quantum dot (QD) laser operating in double-state lasing regime at high pump level, was proposed. The difference between electron and hole capture rates causes the depletion of the hole levels and consequently leads to the decrease of an output lasing power via QD ground state with the growth of injection. Moreover, it was shown that the hole-to-electron capture rates ratio strongly affects both the light-current curve and the key laser parameters. The model of the simultaneous lasing through the ground and excited QD states was developed which allows to describe the observed quenching quantitatively.

Connected health: cancer symptom and quality-of-life assessment using a tablet computer: a pilot study.

PubMed

Aktas, Aynur; Hullihen, Barbara; Shrotriya, Shiva; Thomas, Shirley; Walsh, Declan; Estfan, Bassam

2015-03-01

Incorporation of tablet computers (TCs) into patient assessment may facilitate safe and secure data collection. We evaluated the usefulness and acceptability of a TC as an electronic self-report symptom assessment instrument. Research Electronic Data Capture Web-based application supported data capture. Information was collected and disseminated in real time and a structured format. Completed questionnaires were printed and given to the physician before the patient visit. Most participants completed the survey without assistance. Completion rate was 100%. The median global quality of life was high for all. More than half reported pain. Based on Edmonton Symptom Assessment System, the top 3 most common symptoms were tiredness, anxiety, and decreased well-being. Patient and physician acceptability for these quick and useful TC-based surveys was excellent. © The Author(s) 2013.

Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

DOE PAGES

Swierk, John R.; Méndez-Hernández, Dalvin D.; McCool, Nicholas S.; ...

2015-01-12

Solar fuel generation requires the efficient capture and conversion of visible light. In both natural and artificial systems, molecular sensitizers can be tuned to capture, convert, and transfer visible light energy. We demonstrate that a series of metal-free porphyrins can drive photoelectrochemical water splitting under broadband and red light (λ > 590 nm) illumination in a dye-sensitized TiO 2 solar cell. Here, we report the synthesis, spectral, and electrochemical properties of the sensitizers. Despite slow recombination of photoinjected electrons with oxidized porphyrins, photocurrents are low because of low injection yields and slow electron self-exchange between oxidized porphyrins. As a result,more » the free-base porphyrins are stable under conditions of water photoelectrolysis and in some cases photovoltages in excess of 1 V are observed.« less

PbSnTe:In compound: Electron capture levels, galvanomagnetic properties, and THz sensitivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishchenko, D. V., E-mail: miracle4348@gmail.com; Klimov, A. E.; Shumsky, V. N.

A model of the Pb{sub 1–x}Sn{sub x}Te:In compound, based on concepts of the theory of disordered systems is considered. The temperature dependences of the Fermi-level position and carrier concentration are calculated depending on the indium doping level and are compared with experimental data. The transient current–voltage characteristics are calculated in the mode of injection from the contact and current limitation by space charge at various voltage-variation rates. The data obtained are compared with the experiments. It is demonstrated that the shape of the characteristics is controlled by the parameters of electron capture at localized states. Photocurrent relaxation in a magneticmore » field is studied, and the mechanism of such relaxation is discussed under the assumption of the magnetic freezing of carriers.« less

Electron Capture Supernovae from Close Binary Systems

NASA Astrophysics Data System (ADS)

Poelarends, Arend J. T.; Wurtz, Scott; Tarka, James; Cole Adams, L.; Hills, Spencer T.

2017-12-01

We present the first detailed study of the Electron Capture Supernova Channel (ECSN Channel) for a primary star in a close binary star system. Progenitors of ECSN occupy the lower end of the mass spectrum of supernova progenitors and are thought to form the transition between white dwarf progenitors and core-collapse progenitors. The mass range for ECSN from close binary systems is thought to be wider than the range for single stars, because of the effects of mass transfer on the helium core. Using the MESA stellar evolution code, we explored the parameter space of initial primary masses between 8 and 17 {M}⊙ , using a large grid of models. We find that the initial primary mass and the mass transfer evolution are important factors in the final fate of stars in this mass range. Mass transfer due to Roche lobe overflow during and after carbon burning causes the core to cool down so that it avoids neon ignition, even in helium-free cores with masses up to 1.52 {M}⊙ , which in single stars would ignite neon. If the core is able to contract to high enough densities for electron captures to commence, we find that, for the adopted Ledoux convection criterion, the initial mass range for the primary to evolve into an ECSN is between 13.5 and 17.6 {M}⊙ . The mass ratio, initial period, and mass-loss efficiency only marginally affect the predicted ranges.

Direct Observation of Electron Capture and Reemission by the Divacancy via Charge Transient Positron Spectroscopy

NASA Astrophysics Data System (ADS)

Edwardson, C. J.; Coleman, P. G.; Paez, D. J.; Doylend, J. K.; Knights, A. P.

2013-03-01

Electron capture during forward bias and reemission at zero bias by divacancies in the depletion region of a silicon diode structure at room temperature have been studied for the first time using monoenergetic positrons. The positron response increases essentially linearly with electron current, as a result of increased positron trapping by negatively charged divacancies. The measurements indicate that ≤1% of the divacancies become negatively charged in the steady state at a forward bias of 1 V. Changes in the mean positron response when applying a square wave bias to the sample (1 V forward bias and 0 V, duty cycle 1∶4, times at 0 V in the range 0.1-100μs), were consistent with a rapid conversion of doubly to singly charged divacancies (in ˜101ns), followed by slower defilling of the singly charged divacancies with a time constant of ˜101μs. These ac measurements allow determination of the relative populations of singly and doubly charged divacancies. The results provide confirmation of consistency between the positron’s response to the silicon divacancy and previously extracted capture and emission kinetics determined through charge transient measurements and assigned to the same defect. The possibility of combining these two, orthogonal techniques suggest a promising new and powerful approach to defect spectroscopy in which the structure and electrical properties of a defect may be determined in a single measurement.

Block Copolymer Membranes for Efficient Capture of a Chemotherapy Drug

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, X. Chelsea; Oh, Hee Jeung; Yu, Jay F.

In this paper, we introduce the use of block copolymer membranes for an emerging application, “drug capture”. The polymer is incorporated in a new class of biomedical devices, referred to as ChemoFilter, which is an image-guided temporarily deployable endovascular device designed to increase the efficacy of chemotherapy-based cancer treatment. We show that block copolymer membranes consisting of functional sulfonated polystyrene end blocks and a structural polyethylene middle block (SSES) are capable of capturing doxorubicin, a chemotherapy drug. We focus on the relationship between morphology of the membrane in the ChemoFilter device and efficacy of doxorubicin capture measured in vitro. Usingmore » small-angle X-ray scattering and cryogenic scanning transmission electron microscopy, we discovered that rapid doxorubicin capture is associated with the presence of water-rich channels in the lamellar-forming S-SES membranes in aqueous environment.« less

Block Copolymer Membranes for Efficient Capture of a Chemotherapy Drug

DOE PAGES

Chen, X. Chelsea; Oh, Hee Jeung; Yu, Jay F.; ...

2016-07-23

In this paper, we introduce the use of block copolymer membranes for an emerging application, “drug capture”. The polymer is incorporated in a new class of biomedical devices, referred to as ChemoFilter, which is an image-guided temporarily deployable endovascular device designed to increase the efficacy of chemotherapy-based cancer treatment. We show that block copolymer membranes consisting of functional sulfonated polystyrene end blocks and a structural polyethylene middle block (SSES) are capable of capturing doxorubicin, a chemotherapy drug. We focus on the relationship between morphology of the membrane in the ChemoFilter device and efficacy of doxorubicin capture measured in vitro. Usingmore » small-angle X-ray scattering and cryogenic scanning transmission electron microscopy, we discovered that rapid doxorubicin capture is associated with the presence of water-rich channels in the lamellar-forming S-SES membranes in aqueous environment.« less

Comparison of Muon Capture in Light and in Heavy Nuclei

NASA Astrophysics Data System (ADS)

Measday, David F.; Stocki, Trevor J.

2007-10-01

We have recently completed an experimental study at TRIUMF of muon capture in the following elements, N, Al, Si, Ca, Fe, Ni, I, Au, and Bi. We detected the nuclear gamma rays emitted by the product nuclei after muon capture. The energy of the gamma ray identifies the source nuclide, and thus the reaction which has occurred. Our data are of better quality, and more comprehensive than any other data set in the literature. The (μ-,νn) reaction is always dominant. In light nuclei, reactions such as (μ-,νp) and (μ-,νpn) can occur, but not for heavy nuclei. However the reverse is true for reactions such as (μ-,ν3n) and (μ-,ν4n), which are very rare in light nuclei, but easily detected in heavy elements. We shall discuss how such information can be useful in calculations of neutrino-nucleus interactions, and of electron-capture in supernovae.

Biochar and enhanced phosphate capture: Mapping mechanisms to functional properties.

PubMed

Shepherd, Jessica G; Joseph, Stephen; Sohi, Saran P; Heal, Kate V

2017-07-01

A multi-technique analysis was performed on a range of biochar materials derived from secondary organic resources and aimed at sustainable recovery and re-use of wastewater phosphorus (P). Our purpose was to identify mechanisms of P capture in biochar and thereby inform its future optimisation as a sustainable P fertiliser. The biochar feedstock comprised pellets of anaerobically digested sewage sludge (PAD) or pellets of the same blended in the ratio 9:1 with ochre sourced from minewater treatment (POCAD), components which have limited alternative economic value. In the present study the feedstocks were pyrolysed at two highest treatment temperatures of 450 and 550 °C. Each of the resulting biochars were repeatedly exposed to a 20 mg l -1 PO 4 -P solution, to produce a parallel set of P-exposed biochars. Biochar exterior and/or interior surfaces were quantitatively characterised using laser-ablation (LA)-ICP-MS, X-ray diffraction, X-ray photo-electron spectroscopy (XPS) and scanning electron microscopy coupled with energy dispersive X-ray. The results highlighted the general importance of Fe minerals in P capture. XPS analysis of POCAD550 indicated lower oxidation state Fe2p3 bonding compared to POCAD450, and LA-ICP-MS indicated stronger covariation of Fe and S, even after P exposure. This suggests that low-solubility Fe/S compounds are formed during pyrolysis, are affected by process parameters and impact on P capture. Other data suggested capture roles for aluminium, calcium and silicon. Overall, our analyses suggest that a range of mechanisms for P capture are concurrently active in biochar. We highlighted the potential to manipulate these through choice of form and composition of feedstock as well as pyrolysis processing, so that biochar may be increasingly tailored towards specific functionality. Copyright © 2017 Elsevier Ltd. All rights reserved.

Capillary atmospheric pressure electron capture ionization (cAPECI): a highly efficient ionization method for nitroaromatic compounds.

PubMed

Derpmann, Valerie; Mueller, David; Bejan, Iustinian; Sonderfeld, Hannah; Wilberscheid, Sonja; Koppmann, Ralf; Brockmann, Klaus J; Benter, Thorsten

2014-03-01

We report on a novel method for atmospheric pressure ionization of compounds with elevated electron affinity (e.g., nitroaromatic compounds) or gas phase acidity (e.g., phenols), respectively. The method is based on the generation of thermal electrons by the photo-electric effect, followed by electron capture of oxygen when air is the gas matrix yielding O2(-) or of the analyte directly with nitrogen as matrix. Charge transfer or proton abstraction by O2(-) leads to the ionization of the analytes. The interaction of UV-light with metals is a clean method for the generation of thermal electrons at atmospheric pressure. Furthermore, only negative ions are generated and neutral radical formation is minimized, in contrast to discharge- or dopant assisted methods. Ionization takes place inside the transfer capillary of the mass spectrometer leading to comparably short transfer times of ions to the high vacuum region of the mass spectrometer. This strongly reduces ion transformation processes, resulting in mass spectra that more closely relate to the neutral analyte distribution. cAPECI is thus a soft and selective ionization method with detection limits in the pptV range. In comparison to standard ionization methods (e.g., PTR), cAPECI is superior with respect to both selectivity and achievable detection limits. cAPECI demonstrates to be a promising ionization method for applications in relevant fields as, for example, explosives detection and atmospheric chemistry.

Gamow-Teller strength and lepton captures rates on 66-71Ni in stellar matter

NASA Astrophysics Data System (ADS)

Nabi, Jameel-Un; Majid, Muhammad

Charge-changing transitions play a significant role in stellar weak-decay processes. The fate of the massive stars is decided by these weak-decay rates including lepton (positron and electron) captures rates, which play a consequential role in the dynamics of core collapse. As per previous simulation results, weak interaction rates on nickel (Ni) isotopes have significant influence on the stellar core vis-à-vis controlling the lepton content of stellar matter throughout the silicon shell burning phases of high mass stars up to the presupernova stages. In this paper, we perform a microscopic calculation of Gamow-Teller (GT) charge-changing transitions, in the β-decay and electron capture (EC) directions, for neutron-rich Ni isotopes (66-71Ni). We further compute the associated weak-decay rates for these selected Ni isotopes in stellar environment. The computations are accomplished by employing the deformed proton-neutron quasiparticle random phase approximation (pn-QRPA) model. A recent study showed that the deformed pn-QRPA theory is well suited for the estimation of GT transitions. The astral weak-decay rates are determined over densities in the range of 10-1011g/cm3 and temperatures in the range of 0.01 × 109-30 × 109K. The calculated lepton capture rates are compared with the previous calculation of Pruet and Fuller (PF). The overall comparison demonstrates that, at low stellar densities and high temperatures, our EC rates are bigger by as much as two orders of magnitude. Our results show that, at higher temperatures, the lepton capture rates are the dominant mode for the stellar weak rates and the corresponding lepton emission rates may be neglected.

Photoelectrochemical processes in polymer-tethered CdSe nanocrystals.

PubMed

Shallcross, R Clayton; D'Ambruoso, Gemma D; Pyun, Jeffrey; Armstrong, Neal R

2010-03-03

We demonstrate the electrochemical capture of CdSe semiconductor nanocrystals (NCs), with thiophene-terminated carboxylic acid capping ligands, at the surfaces of electrodeposited poly(thiophene) films (i) poly((diethyl)propylenedixoythiophene), P(Et)(2)ProDOT; (ii) poly(propylenedioxythiophene), PProDOT; and (iii) poly(ethylenedioxythiophene), PEDOT, coupled with the exploration of their photoelectrochemical properties. Host polymer films were created using a kinetically controlled electrodeposition protocol on activated indium-tin oxide electrodes (ITO), producing conformal films that facilitate high rates of electron transfer. ProDOT-terminated, ligand-capped CdSe-NCs were captured at the outer surface of the host polymer films using a unique pulse-potential step electrodeposition protocol, providing for nearly close-packed monolayers of the NCs at the host polymer/solution interface. These polymer-confined CdSe NCs were used as sensitizers in the photoelectrochemical reduction of methyl viologen (MV(+2)). High internal quantum efficiencies (IQEs) are estimated for photoelectrochemical sensitized MV(+2) reduction using CdSe NCs ranging from 3.1 to 7.0 nm diameters. Cathodic photocurrent at high MV(+2) concentrations are limited by the rate of hole-capture by the host polymer from photoexcited NCs. The rate of this hole-capture process is determined by (a) the onset potential for reductive dedoping of the host polymer film; (b) the concentration ratio of neutral to oxidized forms of the host polymer ([P(n)]/[P(ox)]); and (c) the NC diameter, which controls its valence band energy, E(VB). These relationships are consistent with control of photoinduced electron transfer by Marcus-like excess free energy relationships. Our electrochemical assembly methods provide an enabling route to the capture of functional NCs in conducting polymer hosts in both photoelectrochemical and photovoltaic energy conversion systems.

Numerical calculation of charge exchange cross sections for plasma diagnostics

NASA Astrophysics Data System (ADS)

Mendez, Luis

2016-09-01

The diagnostics of impurity density and temperature in the plasma core in tokamak plasmas is carried out by applying the charge exchange recombination spectroscopy (CXRS) technique, where a fast beam of H atoms collides with the plasma particles leading to electron capture reactions with the impurity ions. The diagnostics is based on the emission of the excited ions formed in the electron capture. The application of the CXRS requires the knowledge of accurate state-selective cross sections, which in general are not accessible experimentally, and the calculation of cross sections for the high n capture levels, required for the diagnostics in the intermediate energy domain of the probe beam, is particularly difficult. In this work, we present a lattice numerical method to solve the time dependent Schrödinger equation. The method is based on the GridTDSE package, it is applicable in the wide energy range 1 - 500 keV/u and can be used to assess the accuracy of previous calculations. The application of the method will be illustrated with calculations for collisions of multiply charged ions with H. Work partially supported by project ENE2014-52432-R (Secretaria de Estado de I+D+i, Spain).

A hybrid 3D SEM reconstruction method optimized for complex geologic material surfaces.

PubMed

Yan, Shang; Adegbule, Aderonke; Kibbey, Tohren C G

2017-08-01

Reconstruction methods are widely used to extract three-dimensional information from scanning electron microscope (SEM) images. This paper presents a new hybrid reconstruction method that combines stereoscopic reconstruction with shape-from-shading calculations to generate highly-detailed elevation maps from SEM image pairs. The method makes use of an imaged glass sphere to determine the quantitative relationship between observed intensity and angles between the beam and surface normal, and the detector and surface normal. Two specific equations are derived to make use of image intensity information in creating the final elevation map. The equations are used together, one making use of intensities in the two images, the other making use of intensities within a single image. The method is specifically designed for SEM images captured with a single secondary electron detector, and is optimized to capture maximum detail from complex natural surfaces. The method is illustrated with a complex structured abrasive material, and a rough natural sand grain. Results show that the method is capable of capturing details such as angular surface features, varying surface roughness, and surface striations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Role of hydrogen in volatile behaviour of defects in SiO2-based electronic devices

NASA Astrophysics Data System (ADS)

Wimmer, Yannick; El-Sayed, Al-Moatasem; Gös, Wolfgang; Grasser, Tibor; Shluger, Alexander L.

2016-06-01

Charge capture and emission by point defects in gate oxides of metal-oxide-semiconductor field-effect transistors (MOSFETs) strongly affect reliability and performance of electronic devices. Recent advances in experimental techniques used for probing defect properties have led to new insights into their characteristics. In particular, these experimental data show a repeated dis- and reappearance (the so-called volatility) of the defect-related signals. We use multiscale modelling to explain the charge capture and emission as well as defect volatility in amorphous SiO2 gate dielectrics. We first briefly discuss the recent experimental results and use a multiphonon charge capture model to describe the charge-trapping behaviour of defects in silicon-based MOSFETs. We then link this model to ab initio calculations that investigate the three most promising defect candidates. Statistical distributions of defect characteristics obtained from ab initio calculations in amorphous SiO2 are compared with the experimentally measured statistical properties of charge traps. This allows us to suggest an atomistic mechanism to explain the experimentally observed volatile behaviour of defects. We conclude that the hydroxyl-E' centre is a promising candidate to explain all the observed features, including defect volatility.

Triple pulse shape discrimination and capture-gated spectroscopy in a composite heterogeneous scintillator

NASA Astrophysics Data System (ADS)

Sharma, M.; Nattress, J.; Wilhelm, K.; Jovanovic, I.

2017-06-01

We demonstrate an all-solid-state design for a composite heterogeneous scintillation detector sensitive to interactions with high-energy photons (gammas), fast neutrons, and thermal neutrons. The scintillator exhibits triple pulse shape discrimination, effectively separating electron recoils, fast neutron recoils, and neutron captures. This is accomplished by combining the properties of two distinct scintillators, whereby a 51-mm diameter, 51-mm tall cylinder of pulse shape discriminating plastic is wrapped by a 320-μm thick sheet of 6LiF:ZnS(Ag), optically coupling the scintillators to each other and to the photomultiplier tube. In this way, the sensitivity to neutron captures is achieved without the need to load the plastic scintillator with a capture agent. We demonstrate a figure of merit of up to 1.2 for fast neutrons/gammas and 5.7 for thermal neutrons/gammas. Intrinsic capture efficiency is found to be 0.46±0.05% and is in good agreement with simulation, while gamma rejection was 10-6 with respect to the capture region and 10-4 with respect to the recoil region using a 300 keVee threshold. Finally, we show an improvement in capture-gated neutron spectroscopy by rejecting accidental gamma coincidences using pulse shape discrimination in the plastic scintillator.

Secondary electron emission from textured surfaces

NASA Astrophysics Data System (ADS)

Huerta, C. E.; Patino, M. I.; Wirz, R. E.

2018-04-01

In this work, a Monte Carlo model is used to investigate electron induced secondary electron emission for varying effects of complex surfaces by using simple geometric constructs. Geometries used in the model include: vertical fibers for velvet-like surfaces, tapered pillars for carpet-like surfaces, and a cage-like configuration of interlaced horizontal and vertical fibers for nano-structured fuzz. The model accurately captures the secondary electron emission yield dependence on incidence angle. The model shows that unlike other structured surfaces previously studied, tungsten fuzz exhibits secondary electron emission yield that is independent of primary electron incidence angle, due to the prevalence of horizontally-oriented fibers in the fuzz geometry. This is confirmed with new data presented herein of the secondary electron emission yield of tungsten fuzz at incidence angles from 0-60°.

Electron Energization and Mixing Observed by MMS in the Vicinity of an Electron Diffusion Region During Magnetopause Reconnection

NASA Technical Reports Server (NTRS)

Chen, Li-Jen; Hesse, Michael; Wang, Shan; Gershman, Daniel; Ergun, Robert; Pollock, Craig; Torbert, Roy; Bessho, Naoki; Daughton, William; Dorelli, John;

Electron energization and mixing observed by MMS in the vicinity of an electron diffusion region during magnetopause reconnection

NASA Astrophysics Data System (ADS)

Chen, Li-Jen; Hesse, Michael; Wang, Shan; Gershman, Daniel; Ergun, Robert; Pollock, Craig; Torbert, Roy; Bessho, Naoki; Daughton, William; Dorelli, John; Giles, Barbara; Strangeway, Robert; Russell, Christopher; Khotyaintsev, Yuri; Burch, Jim; Moore, Thomas; Lavraud, Benoit; Phan, Tai; Avanov, Levon

2016-06-01

Measurements from the Magnetospheric Multiscale (MMS) mission are reported to show distinct features of electron energization and mixing in the diffusion region of the terrestrial magnetopause reconnection. At the ion jet and magnetic field reversals, distribution functions exhibiting signatures of accelerated meandering electrons are observed at an electron out-of-plane flow peak. The meandering signatures manifested as triangular and crescent structures are established features of the electron diffusion region (EDR). Effects of meandering electrons on the electric field normal to the reconnection layer are detected. Parallel acceleration and mixing of the inflowing electrons with exhaust electrons shape the exhaust flow pattern. In the EDR vicinity, the measured distribution functions indicate that locally, the electron energization and mixing physics is captured by two-dimensional reconnection, yet to account for the simultaneous four-point measurements, translational invariant in the third dimension must be violated on the ion-skin-depth scale.

Advances in structural and functional analysis of membrane proteins by electron crystallography

PubMed Central

Wisedchaisri, Goragot; Reichow, Steve L.; Gonen, Tamir

2011-01-01

Summary Electron crystallography is a powerful technique for the study of membrane protein structure and function in the lipid environment. When well-ordered two-dimensional crystals are obtained the structure of both protein and lipid can be determined and lipid-protein interactions analyzed. Protons and ionic charges can be visualized by electron crystallography and the protein of interest can be captured for structural analysis in a variety of physiologically distinct states. This review highlights the strengths of electron crystallography and the momentum that is building up in automation and the development of high throughput tools and methods for structural and functional analysis of membrane proteins by electron crystallography. PMID:22000511

Advances in structural and functional analysis of membrane proteins by electron crystallography.

PubMed

Wisedchaisri, Goragot; Reichow, Steve L; Gonen, Tamir

2011-10-12

Electron crystallography is a powerful technique for the study of membrane protein structure and function in the lipid environment. When well-ordered two-dimensional crystals are obtained the structure of both protein and lipid can be determined and lipid-protein interactions analyzed. Protons and ionic charges can be visualized by electron crystallography and the protein of interest can be captured for structural analysis in a variety of physiologically distinct states. This review highlights the strengths of electron crystallography and the momentum that is building up in automation and the development of high throughput tools and methods for structural and functional analysis of membrane proteins by electron crystallography. Copyright © 2011 Elsevier Ltd. All rights reserved.

Electronic Still Camera view of Aft end of Wide Field/Planetary Camera in HST

NASA Image and Video Library

1993-12-06

S61-E-015 (6 Dec 1993) --- A close-up view of the aft part of the new Wide Field/Planetary Camera (WFPC-II) installed on the Hubble Space Telescope (HST). WFPC-II was photographed with the Electronic Still Camera (ESC) from inside Endeavour's cabin as astronauts F. Story Musgrave and Jeffrey A. Hoffman moved it from its stowage position onto the giant telescope. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Electron-capture Isotopes Could Constrain Cosmic-Ray Propagation Models

NASA Astrophysics Data System (ADS)

Benyamin, David; Shaviv, Nir J.; Piran, Tsvi

2017-12-01

Electron capture (EC) isotopes are known to provide constraints on the low-energy behavior of cosmic rays (CRs), such as reacceleration. Here, we study the EC isotopes within the framework of the dynamic spiral-arms CR propagation model in which most of the CR sources reside in the galactic spiral arms. The model was previously used to explain the B/C and sub-Fe/Fe ratios. We show that the known inconsistency between the 49Ti/49V and 51V/51Cr ratios remains also in the spiral-arms model. On the other hand, unlike the general wisdom that says the isotope ratios depend primarily on reacceleration, we find here that the ratio also depends on the halo size (Z h) and, in spiral-arms models, also on the time since the last spiral-arm passage ({τ }{arm}). Namely, EC isotopes can, in principle, provide interesting constraints on the diffusion geometry. However, with the present uncertainties in the lab measurements of both the electron attachment rate and the fragmentation cross sections, no meaningful constraint can be placed.

Complexes in the Photocatalytic Reaction of CO2 and H2O: Theoretical Studies

PubMed Central

Luo, Dongmei; Zhang, Ning; Hong, Sanguo; Wu, Huanwen; Liu, Zhihua

2010-01-01

Complexes (H2O/CO2, e–(H2O/CO2) and h+–(H2O/CO2)) in the reaction system of CO2 photoreduction with H2O were researched by B3LYP and MP2 methods along with natural bond orbital (NBO) analysis. Geometries of these complexes were optimized and frequencies analysis performed. H2O/CO2 captured photo-induced electron and hole produced e–(H2O/CO2) and h+–(H2O/CO2), respectively. The results revealed that CO2 and H2O molecules could be activated by the photo-induced electrons and holes, and each of these complexes possessed two isomers. Due to the effect of photo-induced electrons, the bond length of C=O and H-O were lengthened, while H-O bonds were shortened, influenced by holes. The infrared (IR) adsorption frequencies of these complexes were different from that of CO2 and H2O, which might be attributed to the synergistic effect and which could not be captured experimentally. PMID:21152274

Penetration of multiple thin films in micrometeorite capture cells

NASA Technical Reports Server (NTRS)

Simon, Charles G.

1994-01-01

As part of a continuing effort to develop cosmic dust detectors/collectors for use in space, we performed a series of hypervelocity impact experiments on combined sensor/capture-cell assemblies using 10-200-micron-diameter glass projectiles and olivine crystals at velocities of 0.9-14.4 km/s. The design objective of the space-flight instrument is to measure the trajectories of individual particles with sufficient accuracy to permit identification of their parent bodies and to capture enough impactor material to allow chemical and isotopic analyses of samples returned to Earth. Three different multiple-film small-particle capture cell designs (0.1-100-micron-thick Al foils with approx. 10, 100, and 1800 micron spacing) were evaluated for their ability to capture impactor fragments and residue. Their performances were compared to two other types of capture cells, foil covered Ge crystals, and 0.50 and 0.120 g/cu cm aerogels. All capture cells were tested behind multifilm (1.4-6.0-micron-thick) polyvinylidene fluoride (PVDF) velocity/trajectory sensor devices. Several tests were also done without the PVDF sensors for comparison. The results of this study were reported by Simon in a comprehensive report in which the morphology of impacts and impactor residues in various types of capture cells after passage through two PVDF sensor films is discussed. Impactor fragments in selected capture cells from impacts at velocities up to 6.4 km/s were identified using scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS).

Hematopoietic Stem Cell Capture and Directional Differentiation into Vascular Endothelial Cells for Metal Stent-Coated Chitosan/Hyaluronic Acid Loading CD133 Antibody

PubMed Central

Zhang, Fan; Feng, Bo; Fan, Qingyu; Yang, Feng; Shang, Debin; Sui, Jinghan; Zhao, Hong

2015-01-01

A series of metal stents coated with chitosan/hyaluronic acid (CS/HA) loading antibodies by electrostatic self-assembled method were prepared, and the types of cells captured by antibodies and their differentiation in vascular endothelial cells (ECs) evaluated by molecular biology and scanning electron microscope. The results showed that CD133 stent can selectively capture hematopoietic stem cells (HSC),which directionally differentiate into vascular ECs in peripheral blood by (CS/HA) induction, and simultaneously inhibit migration and proliferation of immune cells and vascular smooth muscle cells (MCs). CD34 stent can capture HSC, hematopoietic progenitor cells that differentiate into vascular ECs and immune cells, promoting smooth MCs growth, leading to thrombosis, inflammation, and rejection. CD133 stent can be implanted into miniature pig heart coronary and can repair vascular damage by capturing own HSC, thus contributing to the rapid natural vascular repair, avoiding inflammation and rejection, thrombosis and restenosis. These studies demonstrated that CD133 stent of HSC capture will be an ideal coated metal stent providing a new therapeutic approach for cardiovascular and cerebrovascular disease. PMID:25404533

AMUC: Associated Motion capture User Categories.

PubMed

Norman, Sally Jane; Lawson, Sian E M; Olivier, Patrick; Watson, Paul; Chan, Anita M-A; Dade-Robertson, Martyn; Dunphy, Paul; Green, Dave; Hiden, Hugo; Hook, Jonathan; Jackson, Daniel G

2009-07-13

The AMUC (Associated Motion capture User Categories) project consisted of building a prototype sketch retrieval client for exploring motion capture archives. High-dimensional datasets reflect the dynamic process of motion capture and comprise high-rate sampled data of a performer's joint angles; in response to multiple query criteria, these data can potentially yield different kinds of information. The AMUC prototype harnesses graphic input via an electronic tablet as a query mechanism, time and position signals obtained from the sketch being mapped to the properties of data streams stored in the motion capture repository. As well as proposing a pragmatic solution for exploring motion capture datasets, the project demonstrates the conceptual value of iterative prototyping in innovative interdisciplinary design. The AMUC team was composed of live performance practitioners and theorists conversant with a variety of movement techniques, bioengineers who recorded and processed motion data for integration into the retrieval tool, and computer scientists who designed and implemented the retrieval system and server architecture, scoped for Grid-based applications. Creative input on information system design and navigation, and digital image processing, underpinned implementation of the prototype, which has undergone preliminary trials with diverse users, allowing identification of rich potential development areas.

Phenomenological theory of laser-plasma interaction in ``bubble'' regime

NASA Astrophysics Data System (ADS)

Kostyukov, I.; Pukhov, A.; Kiselev, S.

2004-11-01

The electron trapping in the "bubble" regime of laser-plasma interaction as proposed by Pukhov and Meyer-ter-Vehn [A. Pukhov and J. Meyer-ter-Vehn, Appl. Phys. B 74, 355 (2002)] is studied. In this regime the laser pulse generates a solitary plasma electron cavity: the bubble. It is free from the cold plasma electrons and runs with nearly light velocity. The present work discusses the form of the bubble and the spatial distribution of electromagnetic fields within the cavity. We extend the one-dimensional electron capture theory to the three-dimensional case. It is shown that the bubble can trap plasma electrons. The trapping condition is derived and the trapping cross section is estimated. Electron motion in the self-generated electron bunch is investigated. Estimates for the maximum of electron bunch energy and the bunch density are provided.

Absolute cross sections for electronic excitation of condensed tetrahydrofuran (THF) by 11-16 eV electrons.

PubMed

Lemelin, V; Bass, A D; Cloutier, P; Sanche, L

2016-11-07

Absolute cross section (CS) data on the interaction of low energy electrons with DNA and its molecular constituents are required as input parameters in Monte-Carlo type simulations, for several radiobiological applications. Previously [V. Lemelin et al., J. Chem. Phys. 144, 074701 (2016)], we measured absolute vibrational CSs for low-energy electron scattering from condensed tetrahydrofuran, a convenient surrogate for the deoxyribose. Here we report absolute electronic CSs for energy losses of between 6 and 11.5 eV, by electrons with energies between 11 and 16 eV. The variation of these CSs with incident electron energy shows no evidence of transient anion states, consistent with theoretical and other experimental results, indicating that initial electron capture leading to DNA strand breaks occurs primarily on DNA bases or the phosphate group.

Electron capture cross sections by O+ from atomic He

NASA Astrophysics Data System (ADS)

Joseph, Dwayne C.; Saha, Bidhan C.

2009-11-01

The adiabatic representation is used in both the quantal and semi classical molecular orbital close coupling methods (MOCC) to evaluate charge exchange cross sections. Our results show good agreement with experimental cross sections

Time-dependent first-principles study of angle-resolved secondary electron emission from atomic sheets

NASA Astrophysics Data System (ADS)

Ueda, Yoshihiro; Suzuki, Yasumitsu; Watanabe, Kazuyuki

2018-02-01

Angle-resolved secondary electron emission (ARSEE) spectra were analyzed for two-dimensional atomic sheets using a time-dependent first-principles simulation of electron scattering. We demonstrate that the calculated ARSEE spectra capture the unoccupied band structure of the atomic sheets. The excitation dynamics that lead to SEE have also been revealed by the time-dependent Kohn-Sham decomposition scheme. In the present study, the mechanism for the experimentally observed ARSEE from atomic sheets is elucidated with respect to both energetics and the dynamical aspects of SEE.

Small Aperture BPM to Quadrupole Assembly Tolerance Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fong, K. W.

2010-12-07

The LCLS injector and linac systems utilize a series of quadrupole magnets with a beam position monitor (BPM) captured in the magnet pole tips. The BPM measures the electron beam position by comparing the electrical signal from 4 electrodes and interpolating beam position from these signals. The manufacturing tolerances of the magnet and BPM are critical in determining the mechanical precision of the electrodes relative to the nominal electron beam Z-axis. This study evaluates the statistical uncertainty of the electrodes center axis relative to the nominal electron beam axis.

Exchange-correlation approximations for reduced-density-matrix-functional theory at finite temperature: Capturing magnetic phase transitions in the homogeneous electron gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baldsiefen, Tim; Cangi, Attila; Eich, F. G.

Here, we derive an intrinsically temperature-dependent approximation to the correlation grand potential for many-electron systems in thermodynamical equilibrium in the context of finite-temperature reduced-density-matrix-functional theory (FT-RDMFT). We demonstrate its accuracy by calculating the magnetic phase diagram of the homogeneous electron gas. We compare it to known limits from highly accurate quantum Monte Carlo calculations as well as to phase diagrams obtained within existing exchange-correlation approximations from density functional theory and zero-temperature RDMFT.

Exchange-correlation approximations for reduced-density-matrix-functional theory at finite temperature: Capturing magnetic phase transitions in the homogeneous electron gas

DOE PAGES

Baldsiefen, Tim; Cangi, Attila; Eich, F. G.; ...

2017-12-18

Here, we derive an intrinsically temperature-dependent approximation to the correlation grand potential for many-electron systems in thermodynamical equilibrium in the context of finite-temperature reduced-density-matrix-functional theory (FT-RDMFT). We demonstrate its accuracy by calculating the magnetic phase diagram of the homogeneous electron gas. We compare it to known limits from highly accurate quantum Monte Carlo calculations as well as to phase diagrams obtained within existing exchange-correlation approximations from density functional theory and zero-temperature RDMFT.

A screened independent atom model for the description of ion collisions from atomic and molecular clusters

NASA Astrophysics Data System (ADS)

Lüdde, Hans Jürgen; Horbatsch, Marko; Kirchner, Tom

2018-05-01

We apply a recently introduced model for an independent-atom-like calculation of ion-impact electron transfer and ionization cross sections to proton collisions from water, neon, and carbon clusters. The model is based on a geometrical interpretation of the cluster cross section as an effective area composed of overlapping circular disks that are representative of the atomic contributions. The latter are calculated using a time-dependent density-functional-theory-based single-particle description with accurate exchange-only ground-state potentials. We find that the net capture and ionization cross sections in p-X n collisions are proportional to n α with 2/3 ≤ α ≤ 1. For capture from water clusters at 100 keV impact energy α is close to one, which is substantially different from the value α = 2/3 predicted by a previous theoretical work based on the simplest-level electron nuclear dynamics method. For ionization at 100 keV and for capture at lower energies we find smaller α values than for capture at 100 keV. This can be understood by considering the magnitude of the atomic cross sections and the resulting overlaps of the circular disks that make up the cluster cross section in our model. Results for neon and carbon clusters confirm these trends. Simple parametrizations are found which fit the cross sections remarkably well and suggest that they depend on the relevant bond lengths.

Computer-generated scenes depicting the HST capture and EVA repair mission

NASA Image and Video Library

1993-11-12

Computer generated scenes depicting the Hubble Space Telescope capture and a sequence of planned events on the planned extravehicular activity (EVA). Scenes include the Remote Manipulator System (RMS) arm assisting two astronauts changing out the Wide Field/Planetary Camera (WF/PC) (48699); RMS arm assisting in the temporary mating of the orbiting telescope to the flight support system in Endeavour's cargo bay (48700); Endeavour's RMS arm assisting in the "capture" of the orbiting telescope (48701); Two astronauts changing out the telescope's coprocessor (48702); RMS arm assistign two astronauts replacing one of the telescope's electronic control units (48703); RMS assisting two astronauts replacing the fuse plugs on the telescope's Power Distribution Unit (PDU) (48704); The telescope's High Resolution Spectrograph (HRS) kit is depicted in this scene (48705); Two astronauts during the removal of the high speed photometer and the installation of the COSTAR instrument (48706); Two astronauts, standing on the RMS, during installation of one of the Magnetic Sensing System (MSS) (48707); High angle view of the orbiting Space Shuttle Endeavour with its cargo bay doors open, revealing the bay's pre-capture configuration. Seen are, from the left, the Solar Array Carrier, the ORU Carrier and the flight support system (48708); Two astronauts performing the replacement of HST's Rate Sensor Units (RSU) (48709); The RMS arm assisting two astronauts with the replacement of the telescope's solar array panels (48710); Two astronauts replacing the telescope's Solar Array Drive Electronics (SADE) (48711).

Characterization of low temperature metallic magnetic calorimeters having gold absorbers with implanted 163Ho ions

NASA Astrophysics Data System (ADS)

Gastaldo, L.; Ranitzsch, P. C.-O.; von Seggern, F.; Porst, J.-P.; Schäfer, S.; Pies, C.; Kempf, S.; Wolf, T.; Fleischmann, A.; Enss, C.; Herlert, A.; Johnston, K.

2013-05-01

For the first time we have investigated the behavior of fully micro-fabricated low temperature metallic magnetic calorimeters (MMCs) after undergoing an ion-implantation process. This experiment had the aim to show the possibility to perform a high precision calorimetric measurement of the energy spectrum following the electron capture of 163Ho using MMCs having the radioactive 163Ho ions implanted in the absorber. The isotope 163Ho decays through electron capture to 163Dy and features the smallest known QEC value. This peculiarity makes 163Ho a very interesting candidate to investigate the value of the electron neutrino mass by the analysis of the energy spectrum. The implantation of 163Ho ions was performed at ISOLDE-CERN. The performance of a detector that underwent an ion-implantation process is compared to the one of a detector without implanted ions. The results show that the implantation dose of ions used in this experiment does not compromise the properties of the detector. Moreover the performance of the detector prototype having the 163Ho ions implanted in the absorber is already close to the requirements needed for an experiment with sub-eV sensitivity to the electron neutrino mass. Based on these results, an optimized detector design for future 163Ho experiments is presented.

Ultralow Energy Electron Attachment at Sub-Millielectron Volt Resolution

NASA Astrophysics Data System (ADS)

Chutjian, Ara

1999-10-01

The technique of rare-gas photoionization(J. M. Ajello and A. Chutjian, J. Chem. Phys. 65), 5524 (1976). has been extended(A. Kortyna, M. Darrach and A. Chutjian, Bull. Am. Phys. Soc. 43), 1336 (1998). by use of direct laser ionization to electron energies ɛ in the range 0-100 meV, with a resolution Δɛ of 0.4-0.5 meV (FWHM). Tunable UV light at λ276 nm is produced using a pulsed Nd:YAG laser and nonlinear mixing techniques. The beam is frequency tripled in a pulsed jet of xenon. The VUV radiation, tunable at λ92 nm, is then used to photoionize Xe at its ^2P_1/2 threshold (single-photon ionization). The photoelectrons produced interact with admixed target gas to generate negative ions through the s-wave capture process. Recent results in electron attachment to SF6 will be reported which show resonance structure at the opening of the ground-state vibrational channels.^3,(H. Hotop et al., AIP Conf. Proc. Ser. 360 (AIP, New York, 1995), and private communication.) This structure corresponds to the process of vibrational excitation + attachment, which is superimposed on the underlying s-wave (direct) capture process. It should be a general phenomenon, present in a wide variety of zero-energy electron attaching molecules.

Transferable Pseudo-Classical Electrons for Aufbau of Atomic Ions

PubMed Central

Ekesan, Solen; Kale, Seyit; Herzfeld, Judith

2014-01-01

Generalizing the LEWIS reactive force field from electron pairs to single electrons, we present LEWIS• in which explicit valence electrons interact with each other and with nuclear cores via pairwise interactions. The valence electrons are independently mobile particles, following classical equations of motion according to potentials modified from Coulombic as required to capture quantum characteristics. As proof of principle, the aufbau of atomic ions is described for diverse main group elements from the first three rows of the periodic table, using a single potential for interactions between electrons of like spin and another for electrons of unlike spin. The electrons of each spin are found to distribute themselves in a fashion akin to the major lobes of the hybrid atomic orbitals, suggesting a pointillist description of the electron density. The broader validity of the LEWIS• force field is illustrated by predicting the vibrational frequencies of diatomic and triatomic hydrogen species. PMID:24752384

Transferable pseudoclassical electrons for aufbau of atomic ions.

PubMed

Ekesan, Solen; Kale, Seyit; Herzfeld, Judith

2014-06-05

Generalizing the LEWIS reactive force field from electron pairs to single electrons, we present LEWIS• in which explicit valence electrons interact with each other and with nuclear cores via pairwise interactions. The valence electrons are independently mobile particles, following classical equations of motion according to potentials modified from Coulombic as required to capture quantum characteristics. As proof of principle, the aufbau of atomic ions is described for diverse main group elements from the first three rows of the periodic table, using a single potential for interactions between electrons of like spin and another for electrons of unlike spin. The electrons of each spin are found to distribute themselves in a fashion akin to the major lobes of the hybrid atomic orbitals, suggesting a pointillist description of the electron density. The broader validity of the LEWIS• force field is illustrated by predicting the vibrational frequencies of diatomic and triatomic hydrogen species. Copyright © 2014 Wiley Periodicals, Inc.

Surface engineering on mesoporous silica chips for enriching low molecular weight phosphorylated proteins

NASA Astrophysics Data System (ADS)

Hu, Ye; Peng, Yang; Lin, Kevin; Shen, Haifa; Brousseau, Louis C., III; Sakamoto, Jason; Sun, Tong; Ferrari, Mauro

2011-02-01

Phosphorylated peptides and proteins play an important role in normal cellular activities, e.g., gene expression, mitosis, differentiation, proliferation, and apoptosis, as well as tumor initiation, progression and metastasis. However, technical hurdles hinder the use of common fractionation methods to capture phosphopeptides from complex biological fluids such as human sera. Herein, we present the development of a dual strategy material that offers enhanced capture of low molecular weight phosphoproteins: mesoporous silica thin films with precisely engineered pore sizes that sterically select for molecular size combined with chemically selective surface modifications (i.e. Ga3+, Ti4+ and Zr4+) that target phosphoroproteins. These materials provide high reproducibility (CV = 18%) and increase the stability of the captured proteins by excluding degrading enzymes, such as trypsin. The chemical and physical properties of the composite mesoporous thin films were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and ellipsometry. Using mass spectroscopy and biostatistics analysis, the enrichment efficiency of different metal ions immobilized on mesoporous silica chips was investigated. The novel technology reported provides a platform capable of efficiently profiling the serum proteome for biomarker discovery, forensic sampling, and routine diagnostic applications.Phosphorylated peptides and proteins play an important role in normal cellular activities, e.g., gene expression, mitosis, differentiation, proliferation, and apoptosis, as well as tumor initiation, progression and metastasis. However, technical hurdles hinder the use of common fractionation methods to capture phosphopeptides from complex biological fluids such as human sera. Herein, we present the development of a dual strategy material that offers enhanced capture of low molecular weight phosphoproteins: mesoporous silica thin films with precisely engineered pore sizes that sterically select for molecular size combined with chemically selective surface modifications (i.e. Ga3+, Ti4+ and Zr4+) that target phosphoroproteins. These materials provide high reproducibility (CV = 18%) and increase the stability of the captured proteins by excluding degrading enzymes, such as trypsin. The chemical and physical properties of the composite mesoporous thin films were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and ellipsometry. Using mass spectroscopy and biostatistics analysis, the enrichment efficiency of different metal ions immobilized on mesoporous silica chips was investigated. The novel technology reported provides a platform capable of efficiently profiling the serum proteome for biomarker discovery, forensic sampling, and routine diagnostic applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c0nr00720j

New measurement of θ 13 via neutron capture on hydrogen at Daya Bay

DOE PAGES

F. P. An

2016-04-21

This article reports an improved independent measurement of neutrino mixing angle θ 13 at the Daya Bay Reactor Neutrino Experiment. Electron antineutrinos were identified by inverse β-decays with the emitted neutron captured by hydrogen, yielding a data set with principally distinct uncertainties from that with neutrons captured by gadolinium. With the final two of eight antineutrino detectors installed, this study used 621 days of data including the previously reported 217-day data set with six detectors. The dominant statistical uncertainty was reduced by 49%. Intensive studies of the cosmogenic muon-induced 9Li and fast neutron backgrounds and the neutron-capture energy selection efficiency,more » resulted in a reduction of the systematic uncertainty by 26%. The deficit in the detected number of antineutrinos at the far detectors relative to the expected number based on the near detectors yielded sin 22θ 13 = 0.071 ± 0.011 in the three-neutrino-oscillation framework. As a result, the combination of this result with the gadolinium-capture result is also reported.« less

Node 1 taken during Expedition 26

NASA Image and Video Library

2010-11-26

ISS026-E-005318 (26 Nov. 2010) --- A fish-eye lens attached to an electronic still camera was used by an Expedition 26 crew member to capture this image of the Unity node of the International Space Station.

Node 1 taken during Expedition 26

NASA Image and Video Library

2010-11-26

ISS026-E-005316 (26 Nov. 2010) --- A fish-eye lens attached to an electronic still camera was used by an Expedition 26 crew member to capture this image of the Unity node of the International Space Station.

77 FR 11588 - Certain Electronic Devices for Capturing and Transmitting Images, and Components Thereof

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-27

.... 1337, on behalf of Eastman Kodak Company of Rochester, New York. Letters supplementing the complaint...: Eastman Kodak Company, 343 State Street Rochester, NY 14650. (b) The respondent is the following entity...

Examination of the possible enhancement of neutrinoless double-electron capture in 78Kr

NASA Astrophysics Data System (ADS)

Bustabad, S.; Bollen, G.; Brodeur, M.; Lincoln, D. L.; Novario, S. J.; Redshaw, M.; Ringle, R.; Schwarz, S.

2013-09-01

Penning-trap mass spectrometry was used at the Low-Energy Beam and Ion Trap (LEBIT) facility at the National Superconducting Cyclotron Laboratory (NSCL) to investigate 78Kr, a candidate for resonantly enhanced neutrinoless double-electron capture (0νECEC). The newly determined Q value of 2847.75 (27) keV is 1.4 keV greater than the value from the most recent atomic mass evaluation [Chin. Phys. C1674-113710.1088/1674-1137/36/12/003 36, 1603 (2012)], a change of two sigma, and the uncertainty has been reduced by a factor of three. The change in the Q value shifts allowed 0νECEC in 78Kr further from resonant enhancement. With the improved determination of the Q value, all known excited states can now be confidently excluded from possible 78Se candidates that could lead to resonantly enhanced 0νECEC.

Formation of negative hydrogen ion: polarization electron capture and nonthermal shielding.

PubMed

Ki, Dae-Han; Jung, Young-Dae

2012-09-07

The influence of the nonthermal shielding on the formation of the negative hydrogen ion (H(-)) by the polarization electron capture are investigated in partially ionized generalized Lorentzian plasmas. The Bohr-Lindhard method has been applied to obtain the negative hydrogen formation radius and cross section as functions of the collision energy, de Broglie wave length, Debye length, impact parameter, and spectral index of the plasma. The result shows that the nonthermal character of the plasma enhances the formation radius of the negative hydrogen, especially, for small Debye radii. It is found that the nonthermal effect increases the formation cross section of the negative hydrogen. It is also found that the maximum position of the formation cross section approaches to the collision center with an increase of the spectral index. In addition, it is found that the formation cross section significantly decreases with an increase of the Debye length, especially, for small spectral indices.

Electron capture by Ne3+ ions from atomic hydrogen

NASA Astrophysics Data System (ADS)

Rejoub, R.; Bannister, M. E.; Havener, C. C.; Savin, D. W.; Verzani, C. J.; Wang, J. G.; Stancil, P. C.

2004-05-01

Using the Oak Ridge National Laboratory ion-atom merged-beam apparatus, absolute total electron-capture cross sections have been measured for collisions of Ne3+ ions with hydrogen (deuterium) atoms at energies between 0.07 and 826 eV/u . Comparison to previous measurements shows large discrepancies between 50 and 400 eV/u . Previously published molecular-orbital close-coupling (MOCC) calculations were performed over limited energy ranges, but show good agreement with the present measurements. Here MOCC calculations are presented for energies between 0.01 and 1000 eV/u for collisions with both H and D. For energies below ˜1 eV/u , an enhancement in the magnitude of both the experimental and theoretical cross sections is observed which is attributed to the ion-induced dipole attraction between the reactants. Below ˜4 eV/u , the present calculations show a significant target isotope effect.

Determination of nitrosourea compounds in brain tissue by gas chromatography and electron capture detection.

PubMed

Hassenbusch, S J; Colvin, O M; Anderson, J H

1995-07-01

A relatively simple, high-sensitivity gas chromatographic assay is described for nitrosourea compounds, such as BCNU [1,3-bis(2-chloroethyl)-1-nitrosourea] and MeCCNU [1-(2-chloroethyl)-3-(trans-4-methylcyclohexyl)-1-nitrosourea], in small biopsy samples of brain and other tissues. After extraction with ethyl acetate, secondary amines in BCNU and MeCCNU are derivatized with trifluoroacetic anhydride. Compounds are separated and quantitated by gas chromatography using a capillary column with temperature programming and an electron capture detector. Standard curves of BCNU indicate a coefficient of variance of 0.066 +/- 0.018, a correlation coefficient of 0.929, and an extraction efficiency from whole brain of 68% with a minimum detectable amount of 20 ng in 5-10 mg samples. The assay has been facile and sensitive in over 1000 brain biopsy specimens after intravenous and intraarterial infusions of BCNU.

Kinetic energy spectra in thermionic emission from small tungsten cluster anions: evidence for nonclassical electron capture.

PubMed

Concina, Bruno; Baguenard, Bruno; Calvo, Florent; Bordas, Christian

2010-03-14

The delayed electron emission from small mass-selected anionic tungsten clusters W(n)(-) has been studied for sizes in the range 9 < or = n < or = 21. Kinetic energy spectra have been measured for delays of about 100 ns after laser excitation by a velocity-map imaging spectrometer. They are analyzed in the framework of microreversible statistical theories. The low-energy behavior shows some significant deviations with respect to the classical Langevin capture model, which we interpret as possibly due to the influence of quantum dynamical effects such as tunneling through the centrifugal barrier, rather than shape effects. The cluster temperature has been extracted from both the experimental kinetic energy spectrum and the absolute decay rate. Discrepancies between the two approaches suggest that the sticking probability can be as low as a few percent for the smallest clusters.

Soft x-ray emission from solar wind charge exchange in the laboratory

NASA Astrophysics Data System (ADS)

Shimaya, H.; Ishida, T.; Ishikawa, S.; Suda, S.; Tanuma, H.; Akamatsu, H.; Ohashi, H.; Ijima, N.; Inoue, M.; Ezoe, Y.; Ishisaki, Y.; Ohashi, T.; Shinozaki, K.; Mitsuda, K.; Liu, L.; Wang, J.

2013-09-01

We have observed the emission spectra in collisions of bare oxygen ions with a helium gas target in the soft x-ray region with a window-less silicon drift detector at the collision energy range of 48-80 keV. The dominant soft x-ray emission corresponds to the 1s-2p transition of hydrogen-like oxygen O7+ produced by the single-electron charge exchange reaction. Other emission lines are the 1s-3p, 1s-4p and 1s-5p transitions of O7+, and also the 1s2-1s2p transition of O6+ produced by the true double-electron capture. The cascades from the upper states result in a large population of the 2p state, even though the direct capture into the 2p state is extremely scarcer than those into the 3p, 4p and 5p states.

Studying Electron-Capture on ^64Zn in Supernovae with the (t,^3He) Charge-Exchange Reaction

NASA Astrophysics Data System (ADS)

Hitt, G. W.; Austin, Sam M.; Bazin, D.; Gade, A.; Guess, C. J.; Galaviz-Redondo, D.; Shimbara, Y.; Tur, C.; Zegers, R. G. T.; Horoi, M.; Howard, M. E.; Smith, E. E.

2008-10-01

A secondary, 115 MeV/u triton beam has been developed at NSCL for use in (t,^3He) charge-exchange(CE) reaction studies. This (n,p)-type CE reaction is useful for extracting the full Gamow-Teller (GT) response of the nucleus, overcoming Q-value restrictions present in conventional beta-decay studies. The strength (B(GT)) in ^64Cu has been determined from the absolute cross section measurement of ^64Zn(t,^3He) near zero-degrees, exploiting an empirical proportionality between cross section and B(GT). The detailed features of the B(GT) distribution in a nucleus has an important impact on electron-capture (EC) rates in Type Ia and Core-Collapse supernovae. The measured B(GT) in ^64Cu is directly compared with the results of modern shell model interactions which are used to calculate the GT contribution to EC on nuclei in supernova simulations.

The Knowledge Program: an Innovative, Comprehensive Electronic Data Capture System and Warehouse

PubMed Central

Katzan, Irene; Speck, Micheal; Dopler, Chris; Urchek, John; Bielawski, Kay; Dunphy, Cheryl; Jehi, Lara; Bae, Charles; Parchman, Alandra

2011-01-01

Data contained in the electronic health record (EHR) present a tremendous opportunity to improve quality-of-care and enhance research capabilities. However, the EHR is not structured to provide data for such purposes: most clinical information is entered as free text and content varies substantially between providers. Discrete information on patients’ functional status is typically not collected. Data extraction tools are often unavailable. We have developed the Knowledge Program (KP), a comprehensive initiative to improve the collection of discrete clinical information into the EHR and the retrievability of data for use in research, quality, and patient care. A distinct feature of the KP is the systematic collection of patient-reported outcomes, which is captured discretely, allowing more refined analyses of care outcomes. The KP capitalizes on features of the Epic EHR and utilizes an external IT infrastructure distinct from Epic for enhanced functionality. Here, we describe the development and implementation of the KP. PMID:22195124

A Semiempirical Formula for Single-Electron-Capture Cross Sections of Multiply Charged Ions Colliding with H, H2 and He

NASA Astrophysics Data System (ADS)

Nakai, Yohta; Shirai, Toshizo; Tabata, Tatsuo; Ito, Rinsuke

1989-01-01

A universal analytic formula is given for the total cross sections of single-electron capture by multiply-charged ions colliding with H, H2 or He. Values of constants in the formula have been determined by least-squares fit to experimental data collected from the literature. The formula is applicable to ions of almost all atomic species with charge q greater than 4 (for the H and H2 targets) or 5 (for the He target) in the energy region from about 1 to 107 eV amu-1. The root-mean-square deviation of the data from the formula is 29%. The formula shows that the cross sections are proportional to q1.07 at low energies and to q2.86 at high energies. Other trends of the cross sections that can be derived from the formula are also discussed.

Communication: Alamethicin can capture lipid-like molecules in the membrane

NASA Astrophysics Data System (ADS)

Afanasyeva, Ekaterina F.; Syryamina, Victoria N.; Dzuba, Sergei A.

2017-01-01

Alamethicin (Alm) is a 19-mer antimicrobial peptide produced by fungus Trichoderma viride. Above a threshold concentration, Alm forms pores across the membrane, providing a mechanism of its antimicrobial action. Here we show that at a small concentration which is below the threshold value, Alm participates in formation of nanoscale lipid-mediated clusters of guest lipid-like molecules in the membrane. These results are obtained by electron spin echo (ESE) technique—a pulsed version of electron paramagnetic resonance—on spin-labeled stearic acid in a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer with Alm added at 1/200 peptide-to-lipid ratio. ESE decay measurements are interpreted assuming that stearic acid molecules in the membrane are assembling around the Alm molecule. One may suggest that this Alm capturing effect on the guest lipid-like molecules could be important for the peptide antimicrobial action.

Excited nuclei, resonances and reactions in neutron star crusts

NASA Astrophysics Data System (ADS)

Takibayev, N.; Nasirova, D.; Katō, K.; Kurmangaliyeva, V.

2018-01-01

The short review of research results concerning the study of reactions and processes that occur in the neutron star crusts is given. The peculiarities of electron capture reactions by a nucleus in overdense crystalline structures have been demonstrated for various nuclei, in particular some even-even nuclei at electron capture reactions give daughter nuclei in excited states. Excited nuclei due to nonlinear interactions lead to a high-order harmonic generation. High energy gammas interact with charged particles, give a neutrino radiation and also knock out nucleons from neighbour nuclei. It is also shown that interactions of neutrons with two and more nuclei in an overdence lattice give a large number of new resonance states. These resonances result in a formation of specific local oscillations in the corresponding layers of the lattice. The periodic enhancement of these processes in the dependence on the elemental composition of the primary neutron star matter is considered.

Classical mapping for Hubbard operators: Application to the double-Anderson model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Bin; Miller, William H.; Levy, Tal J.

A classical Cartesian mapping for Hubbard operators is developed to describe the nonequilibrium transport of an open quantum system with many electrons. The mapping of the Hubbard operators representing the many-body Hamiltonian is derived by using analogies from classical mappings of boson creation and annihilation operators vis-à-vis a coherent state representation. The approach provides qualitative results for a double quantum dot array (double Anderson impurity model) coupled to fermionic leads for a range of bias voltages, Coulomb couplings, and hopping terms. While the width and height of the conduction peaks show deviations from the master equation approach considered to bemore » accurate in the limit of weak system-leads couplings and high temperatures, the Hubbard mapping captures all transport channels involving transition between many electron states, some of which are not captured by approximate nonequilibrium Green function closures.« less

Determining the Binding Sites of β-Cyclodextrin and Peptides by Electron-Capture Dissociation High Resolution Tandem Mass Spectrometry

NASA Astrophysics Data System (ADS)

Qi, Yulin; Geib, Timon; Volmer, Dietrich A.

2015-07-01

Cyclodextrins (CDs) are a group of cyclic oligosaccharides, which readily form inclusion complexes with hydrophobic compounds to increase bioavailability, thus making CDs ideal drug excipients. Recent studies have also shown that CDs exhibit a wide range of protective effects, preventing proteins from aggregation, degradation, and folding. These effects strongly depend on the binding sites on the protein surface. CDs only exhibit weak interactions with amino acids, however; conventional analytical techniques therefore usually fail to reveal the exact location of the binding sites. Moreover, some studies even suggest that CD inclusion complexes are merely electrostatic adducts. Here, electron capture dissociation (ECD) was applied in this proof-of-concept study to examine the exact nature of the CD/peptide complexes, and CD binding sites were unambiguously located for the first time via Fourier-transform ion cyclotron resonance (FTICR) tandem mass spectrometry.

Gene-specific characterization of human histone H2B by electron capture dissociation.

PubMed

Siuti, Nertila; Roth, Michael J; Mizzen, Craig A; Kelleher, Neil L; Pesavento, James J

2006-02-01

The basis set of protein forms expressed by human cells from the H2B gene family was determined by Top Down Mass Spectrometry. Using Electron Capture Dissociation for MS/MS of H2B isoforms, direct evidence for the expression of unmodified H2B.Q, H2B.A, H2B.K/T, H2B.J, H2B.E, H2B.B, H2B.F, and monoacetylated H2B.A was obtained from asynchronous HeLa cells. H2B.A was the most abundant form, with the overall expression profile not changing significantly in cells arrested in mitosis by colchicine or during mid-S, mid-G2, G2/M, and mid-G1 phases of the cell cycle. Modest hyperacetylation of H2B family members was observed after sodium butyrate treatment.

Toxicology of 2,4-dichlorophenoxyacetic acid (2,4-D) and its determination in serum and brain tissue using gas chromatography-electron-capture detection.

PubMed

Oliveira, G H; Palermo-Neto, J

1995-01-01

A gas-liquid chromatographic method with an electron-capture detector was applied for 2,4-dichlorophenoxyacetic acid (2,4-D) determination in the serum and brain tissue of rats acutely intoxicated with the dimethylamine salt of 2,4-D. After extraction with ethyl ether, 2,4-D derivatization was performed using 2-chloroethanol and BCI3. The average recovery values found for serum and brain tissue were 98.5 +/- 4.8 and 93.3 +/- 7.5, respectively. The sensitivity limit of the method was 250 ng/mL for serum and 300 ng/g for brain tissue. The toxic effects of 2,4-D in rats were observed within one-half hour after its oral administration. Results suggest that the toxic mechanism of 2,4-D is related to an action on the central nervous system.

Isolation and recovery of selected polybrominated diphenyl ethers from human serum and sheep serum: coupling reversed-phase solid-phase disk extraction and liquid-liquid extraction techniques with a capillary gas chromatographic electron capture negative ion mass spectrometric determinative technique.

PubMed

Loconto, Paul R; Isenga, David; O'Keefe, Michael; Knottnerus, Mark

2008-01-01

Polybrominated diphenyl ethers (PBDEs) are isolated and recovered with acceptable percent recoveries from human serum via liquid-liquid extraction and column chromatographic cleanup and fractionation with quantitation using capillary gas chromatography-mass spectrometry with electron capture negative ion and selected ion monitoring. PBDEs are found in unspiked serum. An alternative sample preparation approach is developed using sheep serum that utilizes a formic acid pre-treatment followed by reversed-phase solid-phase disk extraction and normal-phase solid-phase cleanup using acidified silica gel that yields>50% recoveries. When these percent recoveries are combined with a minimized phase ratio for human serum and very low instrument detection limits, method detection limits below 500 parts-per-trillion are realized.

Measurement of the intensity ratio of Auger and conversion electrons for the electron capture decay of 125I.

PubMed

Alotiby, M; Greguric, I; Kibédi, T; Lee, B Q; Roberts, M; Stuchbery, A E; Tee, Pi; Tornyi, T; Vos, M

2018-03-21

Auger electrons emitted after nuclear decay have potential application in targeted cancer therapy. For this purpose it is important to know the Auger electron yield per nuclear decay. In this work we describe a measurement of the ratio of the number of conversion electrons (emitted as part of the nuclear decay process) to the number of Auger electrons (emitted as part of the atomic relaxation process after the nuclear decay) for the case of 125 I. Results are compared with Monte-Carlo type simulations of the relaxation cascade using the BrIccEmis code. Our results indicate that for 125 I the calculations based on rates from the Evaluated Atomic Data Library underestimate the K Auger yields by 20%.

Measurement of the intensity ratio of Auger and conversion electrons for the electron capture decay of 125I

NASA Astrophysics Data System (ADS)

Alotiby, M.; Greguric, I.; Kibédi, T.; Lee, B. Q.; Roberts, M.; Stuchbery, A. E.; Tee, Pi; Tornyi, T.; Vos, M.

2018-03-01

Auger electrons emitted after nuclear decay have potential application in targeted cancer therapy. For this purpose it is important to know the Auger electron yield per nuclear decay. In this work we describe a measurement of the ratio of the number of conversion electrons (emitted as part of the nuclear decay process) to the number of Auger electrons (emitted as part of the atomic relaxation process after the nuclear decay) for the case of 125I. Results are compared with Monte-Carlo type simulations of the relaxation cascade using the BrIccEmis code. Our results indicate that for 125I the calculations based on rates from the Evaluated Atomic Data Library underestimate the K Auger yields by 20%.

Modeling radiation belt electron dynamics during GEM challenge intervals with the DREAM3D diffusion model

NASA Astrophysics Data System (ADS)

Tu, Weichao; Cunningham, G. S.; Chen, Y.; Henderson, M. G.; Camporeale, E.; Reeves, G. D.

2013-10-01

a response to the Geospace Environment Modeling (GEM) "Global Radiation Belt Modeling Challenge," a 3D diffusion model is used to simulate the radiation belt electron dynamics during two intervals of the Combined Release and Radiation Effects Satellite (CRRES) mission, 15 August to 15 October 1990 and 1 February to 31 July 1991. The 3D diffusion model, developed as part of the Dynamic Radiation Environment Assimilation Model (DREAM) project, includes radial, pitch angle, and momentum diffusion and mixed pitch angle-momentum diffusion, which are driven by dynamic wave databases from the statistical CRRES wave data, including plasmaspheric hiss, lower-band, and upper-band chorus. By comparing the DREAM3D model outputs to the CRRES electron phase space density (PSD) data, we find that, with a data-driven boundary condition at Lmax = 5.5, the electron enhancements can generally be explained by radial diffusion, though additional local heating from chorus waves is required. Because the PSD reductions are included in the boundary condition at Lmax = 5.5, our model captures the fast electron dropouts over a large L range, producing better model performance compared to previous published results. Plasmaspheric hiss produces electron losses inside the plasmasphere, but the model still sometimes overestimates the PSD there. Test simulations using reduced radial diffusion coefficients or increased pitch angle diffusion coefficients inside the plasmasphere suggest that better wave models and more realistic radial diffusion coefficients, both inside and outside the plasmasphere, are needed to improve the model performance. Statistically, the results show that, with the data-driven outer boundary condition, including radial diffusion and plasmaspheric hiss is sufficient to model the electrons during geomagnetically quiet times, but to best capture the radiation belt variations during active times, pitch angle and momentum diffusion from chorus waves are required.

The electron trap parameter extraction-based investigation of the relationship between charge trapping and activation energy in IGZO TFTs under positive bias temperature stress

NASA Astrophysics Data System (ADS)

Rhee, Jihyun; Choi, Sungju; Kang, Hara; Kim, Jae-Young; Ko, Daehyun; Ahn, Geumho; Jung, Haesun; Choi, Sung-Jin; Myong Kim, Dong; Kim, Dae Hwan

2018-02-01

Experimental extraction of the electron trap parameters which are associated with charge trapping into gate insulators under the positive bias temperature stress (PBTS) is proposed and demonstrated for the first time in amorphous indium-gallium-zinc-oxide thin-film transistors. This was done by combining the PBTS/recovery time-evolution of the experimentally decomposed threshold voltage shift (ΔVT) and the technology computer-aided design (TCAD)-based charge trapping simulation. The extracted parameters were the trap density (NOT) = 2.6 × 1018 cm-3, the trap energy level (ΔET) = 0.6 eV, and the capture cross section (σ0) = 3 × 10-19 cm2. Furthermore, based on the established TCAD framework, the relationship between the electron trap parameters and the activation energy (Ea) is comprehensively investigated. It is found that Ea increases with an increase in σ0, whereas Ea is independent of NOT. In addition, as ΔET increases, Ea decreases in the electron trapping-dominant regime (low ΔET) and increases again in the Poole-Frenkel (PF) emission/hopping-dominant regime (high ΔET). Moreover, our results suggest that the cross-over ΔET point originates from the complicated temperature-dependent competition between the capture rate and the emission rate. The PBTS bias dependence of the relationship between Ea and ΔET suggests that the electric field dependence of the PF emission-based electron hopping is stronger than that of the thermionic field emission-based electron trapping.

Single ionization and capture cross sections from biological molecules by bare projectile impact*

NASA Astrophysics Data System (ADS)

Quinto, Michele A.; Monti, Juan M.; Montenegro, Pablo D.; Fojón, Omar A.; Champion, Christophe; Rivarola, Roberto D.

2017-02-01

We report calculations on single differential and total cross sections for single ionization and single electron capture from biological targets, namely, vapor water and DNA nucleobasese molecules, by bare projectile impact: H+, He2+, and C6+. They are performed within the Continuum Distorted Wave - Eikonal Initial State approximation and compared to several existing experimental data. This study is oriented to the obtention of a reliable set of theoretical data to be used as input in a Monte Carlo code destined to micro- and nano- dosimetry.

Space charge neutralization by electron-transparent suspended graphene

PubMed Central

Srisonphan, Siwapon; Kim, Myungji; Kim, Hong Koo

2014-01-01

Graphene possesses many fascinating properties originating from the manifold potential for interactions at electronic, atomic, or molecular levels. Here we report measurement of electron transparency and hole charge induction response of a suspended graphene anode on top of a void channel formed in a SiO2/Si substrate. A two-dimensional (2D) electron gas induced at the oxide interface emits into air and makes a ballistic transport toward the suspended graphene. A small fraction (>~0.1%) of impinging electrons are captured at the edge of 2D hole system in graphene, demonstrating good transparency to very low energy (<3 eV) electrons. The hole charges induced in the suspended graphene anode have the effect of neutralizing the electron space charge in the void channel. This charge compensation dramatically enhances 2D electron gas emission at cathode to the level far surpassing the Child-Langmuir's space-charge-limited emission. PMID:24441774

Decay studies of neutron deficient nuclei near the Z=64 subshell: 142Dy, 140,142Tb, 140,142Gd, 140,142Eu, 142Sm, and 142Pm

NASA Astrophysics Data System (ADS)

Firestone, R. B.; Gilat, J.; Nitschke, J. M.; Wilmarth, P. A.; Vierinen, K. S.

1991-03-01

The electron-capture and β+-decay branchings (EC/β+) and delayed proton decays of A=142 isotopes with 61<=Z<=66 and A=140 isotopes with 63<=Z<=65 were investigated with the OASIS facility on-line at the Lawrence Berkeley Laboratory SuperHILAC. Electron capture and positron-decay emission probabilities have been determined for 142Pm and 142Sm decays, and extensive decay schemes have been constructed for 142Eug(2.34+/-0.12 s), 142Gd(70.2+/-0.6 s), 140Eu(1.51+/-0.02 s), and 140Gd(15.8+/-0.4 s). Decay schemes for the new isotopes 142Tbg(597+/-17 ms), 142Tbm(303+/-17 ms), 142Dy(2.3+/-0.3 s), 140Eum(125+/-2 ms), and 140Tb(2.4+/-0.2 s) are also presented. We have assigned γ rays to these isotopes on the basis of γγ and xγ coincidences, and from half-life determinations. Electron-capture and β+-decay branchings were measured for each decay, and β-delayed proton branchings were determined for 142Dy, 142Tb, and 140Tb decays. QEC values, derived from the measured EC/β+ branchings and the level schemes are compared with those from the Wapstra and Audi mass evaluation and the Liran and Zeldes mass calculation. The systematics of the N=77 isomer decays are discussed, and the intense 0+-->1+ and 1+-->0+ ground-state beta decays are compared with shell-model predictions for simple spin-flip transitions.

Big Data Quality Case Study Preliminary Findings, U.S. Army MEDCOM MODS

DTIC Science & Technology

2013-09-01

captured in electronic form is relatively small, on the order of hundreds of thousands of health profiles at say around 500K per profile, or in the...in electronic form, then different language identification, handwriting recognition, and Natural Language Processing (NLP) techniques could be used...and patterns” [15]. Volume - The free text fields vary in length from say ten characters to several hundred characters. Other materials can be much

Kelly in the Cupola Module during Expedition 26

NASA Image and Video Library

2010-11-26

ISS026-E-005313 (26 Nov. 2010) --- A fish-eye lens attached to an electronic still camera was used to capture this image of NASA astronaut Scott Kelly, Expedition 26 commander, in the Cupola of the International Space Station.

Scanning electron microscope automatic defect classification of process induced defects

NASA Astrophysics Data System (ADS)

Wolfe, Scott; McGarvey, Steve

2017-03-01

With the integration of high speed Scanning Electron Microscope (SEM) based Automated Defect Redetection (ADR) in both high volume semiconductor manufacturing and Research and Development (R and D), the need for reliable SEM Automated Defect Classification (ADC) has grown tremendously in the past few years. In many high volume manufacturing facilities and R and D operations, defect inspection is performed on EBeam (EB), Bright Field (BF) or Dark Field (DF) defect inspection equipment. A comma separated value (CSV) file is created by both the patterned and non-patterned defect inspection tools. The defect inspection result file contains a list of the inspection anomalies detected during the inspection tools' examination of each structure, or the examination of an entire wafers surface for non-patterned applications. This file is imported into the Defect Review Scanning Electron Microscope (DRSEM). Following the defect inspection result file import, the DRSEM automatically moves the wafer to each defect coordinate and performs ADR. During ADR the DRSEM operates in a reference mode, capturing a SEM image at the exact position of the anomalies coordinates and capturing a SEM image of a reference location in the center of the wafer. A Defect reference image is created based on the Reference image minus the Defect image. The exact coordinates of the defect is calculated based on the calculated defect position and the anomalies stage coordinate calculated when the high magnification SEM defect image is captured. The captured SEM image is processed through either DRSEM ADC binning, exporting to a Yield Analysis System (YAS), or a combination of both. Process Engineers, Yield Analysis Engineers or Failure Analysis Engineers will manually review the captured images to insure that either the YAS defect binning is accurately classifying the defects or that the DRSEM defect binning is accurately classifying the defects. This paper is an exploration of the feasibility of the utilization of a Hitachi RS4000 Defect Review SEM to perform Automatic Defect Classification with the objective of the total automated classification accuracy being greater than human based defect classification binning when the defects do not require multiple process step knowledge for accurate classification. The implementation of DRSEM ADC has the potential to improve the response time between defect detection and defect classification. Faster defect classification will allow for rapid response to yield anomalies that will ultimately reduce the wafer and/or the die yield.

Electronic Structure, Phonon Dynamical Properties, and CO 2 Capture Capability of Na 2 - x M x Zr O 3 ( M = Li ,K): Density-Functional Calculations and Experimental Validations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, Yuhua; Lekse, Jonathan; Wang, Xianfeng

2015-04-22

The electronic structural and phonon properties of Na 2-αM αZrO 3 (M ¼ Li,K, α = ¼ 0.0,0.5,1.0,1.5,2.0) are investigated by first-principles density-functional theory and phonon dynamics. The thermodynamic properties of CO 2 absorption and desorption in these materials are also analyzed. With increasing doping level α, the binding energies of Na 2-αLi αZrO 3 are increased while the binding energies of Na 2-α K αZrO 3 are decreased to destabilize the structures. The calculated band structures and density of states also show that, at the same doping level, the doping sites play a significant role in the electronic properties.more » The phonon dispersion results show that few soft modes are found in several doped configurations, which indicates that these structures are less stable than other configurations with different doping levels. From the calculated relationships among the chemical-potential change, the CO 2 pressure, and the temperature of the CO 2 capture reactions by Na 2-αM αZrO 3, and from thermogravimetric-analysis experimental measurements, the Li- and K-doped mixtures Na 2-αM αZrO 3 have lower turnover temperatures (T t) and higher CO 2 capture capacities, compared to pure Na 2ZrO 3. The Li-doped systems have a larger T t decrease than the K-doped systems. When increasing the Li-doping level α, the T t of the corresponding mixture Na 2-αLi αZrO 3 decreases further to a low-temperature range. However, in the case of K-doped systems Na 2-αK αZrO 3, although doping K into Na 2ZrO 3 initially shifts its T t to lower temperatures, further increases of the K-doping level α causes T t to increase. Therefore, doping Li into Na 2ZrO 3 has a larger influence on its CO 2 capture performance than the K-doped Na 2ZrO 3. Compared with pure solidsM 2ZrO 3, after doping with other elements, these doped systems’ CO 2 capture performances are improved.« less

Highly Surface-Active Ca(OH)2 Monolayer as a CO2 Capture Material.

PubMed

Özçelik, V Ongun; Gong, Kai; White, Claire E

2018-03-14

Greenhouse gas emissions originating from fossil fuel combustion contribute significantly to global warming, and therefore the design of novel materials that efficiently capture CO 2 can play a crucial role in solving this challenge. Here, we show that reducing the dimensionality of bulk crystalline portlandite results in a stable monolayer material, named portlandene, that is highly effective at capturing CO 2 . On the basis of theoretical analysis comprised of ab initio quantum mechanical calculations and force-field molecular dynamics simulations, we show that this single-layer phase is robust and maintains its stability even at high temperatures. The chemical activity of portlandene is seen to further increase upon defect engineering of its surface using vacancy sites. Defect-containing portlandene is capable of separating CO and CO 2 from a syngas (CO/CO 2 /H 2 ) stream, yet is inert to water vapor. This selective behavior and the associated mechanisms have been elucidated by examining the electronic structure, local charge distribution, and bonding orbitals of portlandene. Additionally, unlike conventional CO 2 capturing technologies, the regeneration process of portlandene does not require high temperature heat treatment because it can release the captured CO 2 by application of a mild external electric field, making portlandene an ideal CO 2 capturing material for both pre- and postcombustion processes.

Capture-gated Spectroscopic Measurements of Monoenergetic Neutrons with a Composite Scintillation Detector

NASA Astrophysics Data System (ADS)

Nattress, Jason; Mayer, M.; Foster, A.; Meddeb, A. Barhoumi; Trivelpiece, C.; Ounaies, Z.; Jovanovic, I.

2016-04-01

We report on the measurements of monoenergetic neutrons from DD and DT fusion reactions by use of the capture gating method in a heterogeneous plastic-glass composite scintillation detector. The cylindrical detector is 5.08 cm in diameter and 5.05 cm in height and was fabricated using 1-mm diameter Li-doped glass rods (GS20) and scintillating polyvinyl toluene (EJ-290). Different scintillation decay constants are used to identify energy depositions in two materials constituting the composite scintillator. Geant4 simulations of the neutron thermalization and capture process were conducted, finding a mean capture time of approximately 2.6 μs for both DD and DT neutrons. A capture gating time acceptance window based on simulation results was used to identify the neutron thermalization pulses. The total scintillation light yield produced in neutron thermalization was measured and found to show consistency on event-by-event basis despite the variety of neutron thermalization histories prior to capture. The ratio of light yields from thermalization of 14.1 MeV and 2.45 MeV neutrons in the EJ-290 scintillator was determined to be 14.6, and the light output from 2.45 MeV neutrons was also correlated to its electron equivalent, obtaining a value of 0.58±0.05 MeVee.

Flight-test evaluation of two electronic display formats for approach to landing under instrument conditions

NASA Technical Reports Server (NTRS)

Morello, S. A.; Knox, C. E.; Steinmetz, G. G.

1977-01-01

The results of a flight evaluation of two electronic display formats for the approach to landing under instrument conditions are presented. The evaluation was conducted for a base-line electronic display format and for the same format with runway symbology and track information added. The evaluation was conducted during 3 deg, manual straight-in approaches with and without initial localizer offsets. Flight path tracking performance data and pilot subjective comments were examined with regard to the pilot's ability to capture and maintain localizer and glide slope by using both display formats.

Field emission chemical sensor

DOEpatents

Panitz, J.A.

1983-11-22

A field emission chemical sensor for specific detection of a chemical entity in a sample includes a closed chamber enclosing two field emission electrode sets, each field emission electrode set comprising (a) an electron emitter electrode from which field emission electrons can be emitted when an effective voltage is connected to the electrode set; and (b) a collector electrode which will capture said electrons emitted from said emitter electrode. One of the electrode sets is passive to the chemical entity and the other is active thereto and has an active emitter electrode which will bind the chemical entity when contacted therewith.

Black holes as antimatter factories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bambi, Cosimo; Petrov, Alexey A.; Dolgov, Alexander D., E-mail: cosimo.bambi@ipmu.jp, E-mail: dolgov@fe.infn.it, E-mail: apetrov@physics.wayne.edu

2009-09-01

We consider accretion of matter onto a low mass black hole surrounded by ionized medium. We show that, because of the higher mobility of protons than electrons, the black hole would acquire positive electric charge. If the black hole's mass is about or below 10{sup 20} g, the electric field at the horizon can reach the critical value which leads to vacuum instability and electron-positron pair production by the Schwinger mechanism. Since the positrons are ejected by the emergent electric field, while electrons are back-captured, the black hole operates as an antimatter factory which effectively converts protons into positrons.

Electronic propensity rules in Li-H+ collisions involving initial and/or final oriented states

NASA Astrophysics Data System (ADS)

Salas, P. J.

2000-12-01

Electronic excitation and capture processes are studied in collisions involving systems with only one active electron such as the alkaline (Li)-proton in the medium-energy region (0.1-15 keV). Using the semiclassical impact parameter method, the probabilities and the orientation parameter are calculated for transitions between initial and/or final oriented states. The results show a strong asymmetry in the probabilities depending on the orientation of the initial and/or final states. An intuitive view of the processes, by means of the concepts of propensity and velocity matching rules, is provided.

Compression of subrelativistic space-charge-dominated electron bunches for single-shot femtosecond electron diffraction.

PubMed

van Oudheusden, T; Pasmans, P L E M; van der Geer, S B; de Loos, M J; van der Wiel, M J; Luiten, O J

2010-12-31

We demonstrate the compression of 95 keV, space-charge-dominated electron bunches to sub-100 fs durations. These bunches have sufficient charge (200 fC) and are of sufficient quality to capture a diffraction pattern with a single shot, which we demonstrate by a diffraction experiment on a polycrystalline gold foil. Compression is realized by means of velocity bunching by inverting the positive space-charge-induced velocity chirp. This inversion is induced by the oscillatory longitudinal electric field of a 3 GHz radio-frequency cavity. The arrival time jitter is measured to be 80 fs.

Development of diamond-lanthanide metal oxide affinity composites for the selective capture of endogenous serum phosphopeptides.

PubMed

Hussain, Dilshad; Musharraf, Syed Ghulam; Najam-ul-Haq, Muhammad

2016-02-01

Development of affinity materials for the selective enrichment of phosphopeptides has attracted attention during the last decade. In this work, diamond-lanthanum oxide and diamond-samarium oxide composites have been fabricated via the hydrothermal method. The composites are characterized by scanning electron microscopy (SEM), energy dispersive X-Ray spectroscopy (EDAX), and atomic force microscopy (AFM). The analyses confirm the size and composition of the nanocomposites. They have been applied to selectively capture phosphorylated peptides from standard proteins (β-casein and BSA). Selectivity is calculated as 1:3000 and 1:1500 while sensitivity down to 1 and 20 fmol for diamond-lanthanum oxide and diamond-samarium oxide nanocomposites, respectively. Enrichment efficiency has also been evaluated for non-fat milk digest where 18 phosphopeptides are enriched. Total of 213 and 187 phosphopeptides are captured from tryptic digest of HeLa cells extracted proteins by diamond-lanthanum oxide and diamond-samarium oxide, respectively. Finally, human serum, without any pre-treatment, is applied and nanocomposites capture the endogenous serum phosphopeptides.

Reducing flicker due to ambient illumination in camera captured images

NASA Astrophysics Data System (ADS)

Kim, Minwoong; Bengtson, Kurt; Li, Lisa; Allebach, Jan P.

2013-02-01

The flicker artifact dealt with in this paper is the scanning distortion arising when an image is captured by a digital camera using a CMOS imaging sensor with an electronic rolling shutter under strong ambient light sources powered by AC. This type of camera scans a target line-by-line in a frame. Therefore, time differences exist between the lines. This mechanism causes a captured image to be corrupted by the change of illumination. This phenomenon is called the flicker artifact. The non-content area of the captured image is used to estimate a flicker signal that is a key to being able to compensate the flicker artifact. The average signal of the non-content area taken along the scan direction has local extrema where the peaks of flicker exist. The locations of the extrema are very useful information to estimate the desired distribution of pixel intensities assuming that the flicker artifact does not exist. The flicker-reduced images compensated by our approach clearly demonstrate the reduced flicker artifact, based on visual observation.

Polyethylenimine-incorporated zeolite 13X with mesoporosity for post-combustion CO2 capture

NASA Astrophysics Data System (ADS)

Chen, Chao; Kim, Su-Sung; Cho, Won-Seung; Ahn, Wha-Seung

2015-03-01

X-type zeolite with mesoporosity (Meso-13X) was prepared by using dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride as a mesopore-generating agent, and then modified with polyethylenimine (PEI) through a physical impregnation method to form a hybrid material (Meso-13X-PEI). Meso-13X with and without PEI was characterized by X-ray powder diffraction (XRD), N2 adsorption-desorption isotherm at 77 K, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Meso-13X-PEI exhibited higher CO2 capture capacity than PEI-modified zeolite 13X owing to its larger pore volume that accommodates more amine species inside the pore structure, and the mesoporosity also can facilitate dispersion of PEI molecules inside the pore channels. Compared to zeolite 13X, Meso-13X-PEI showed much higher CO2 capture selectivity (against N2) as well as higher CO2 capture capacity at relatively high temperature (e.g. 100 °C) and dilute CO2 concentration relevant to post-combustion conditions.

Stable glow discharge detector

DOEpatents

Koo, Jackson C.; Yu, Conrad M.

2004-05-18

A highly sensitive electronic ion cell for the measurement of trace elements in He carrier gas which involves glow discharge. A constant wave (CW) stable glow discharge detector which is controlled through a biased resistor, can detect the change of electron density caused by impurities in the He carrier gas by many orders of magnitude larger than that caused by direct ionization or electron capture. The stable glow discharge detector utilizes a floating pseudo-electrode to form a probe in or near the plasma and a solid rod electrode. By using this probe, the large variation of electron density due to trace amounts of impurities can be directly measured. The solid rod electrode provides greater stability and thus easier alignment.

Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

DOE PAGES

Zhang, C. J.; Hua, J. F.; Xu, X. L.; ...

2016-07-11

A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of themore » wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. As a result, the capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.« less

Neutron activation analyses and half-life measurements at the usgs triga reactor

NASA Astrophysics Data System (ADS)

Larson, Robert E.

Neutron activation of materials followed by gamma spectroscopy using high-purity germanium detectors is an effective method for making measurements of nuclear beta decay half-lives and for detecting trace amounts of elements present in materials. This research explores applications of neutron activation analysis (NAA) in two parts. Part 1. High Precision Methods for Measuring Decay Half-Lives, Chapters 1 through 8 Part one develops research methods and data analysis techniques for making high precision measurements of nuclear beta decay half-lives. The change in the electron capture half-life of 51Cr in pure chromium versus chromium mixed in a gold lattice structure is explored, and the 97Ru electron capture decay half-life are compared for ruthenium in a pure crystal versus ruthenium in a rutile oxide state, RuO2. In addition, the beta-minus decay half-life of 71mZn is measured and compared with new high precision findings. Density Functional Theory is used to explain the measured magnitude of changes in electron capture half-life from changes in the surrounding lattice electron configuration. Part 2. Debris Collection Nuclear Diagnostic at the National Ignition Facility, Chapters 9 through 11 Part two explores the design and development of a solid debris collector for use as a diagnostic tool at the National Ignition Facility (NIF). NAA measurements are performed on NIF post-shot debris collected on witness plates in the NIF chamber. In this application NAA is used to detect and quantify the amount of trace amounts of gold from the hohlraum and germanium from the pellet present in the debris collected after a NIF shot. The design of a solid debris collector based on material x-ray ablation properties is given, and calculations are done to predict performance and results for the collection and measurements of trace amounts of gold and germanium from dissociated hohlraum debris.

An analysis of point defects induced by In, Al, Ni, and Sn dopants in Bridgman-grown CdZnTe detectors and their influence on trapping of charge carriers

DOE PAGES

Gul, R.; Roy, U. N.; James, R. B.

2017-03-15

In this paper, we studied point defects induced in Bridgman-grown CdZnTe detectors doped with Indium (In), Aluminium (Al), Nickel (Ni), and Tin (Sn). Point defects associated with different dopants were observed, and these defects were analyzed in detail for their contributions to electron/hole (e/h) trapping. We also explored the correlations between the nature and abundance of the point defects with their influence on the resistivity, electron mobility-lifetime (μτ e) product, and electron trapping time. We used current-deep level transient spectroscopy to determine the energy, capture cross-section, and concentration of each trap. Furthermore, we used the data to determine the trappingmore » and de-trapping times for the charge carriers. In In-doped CdZnTe detectors, uncompensated Cd vacancies (V Cd -) were identified as a dominant trap. The V Cd - were almost compensated in detectors doped with Al, Ni, and Sn, in addition to co-doping with In. Dominant traps related to the dopant were found at E v + 0.36 eV and E v + 1.1 eV, E c + 76 meV and E v + 0.61 eV, E v + 36 meV and E v + 0.86 eV, E v + 0.52 eV and E c + 0.83 eV in CZT:In, CZT:In + Al, CZT:In + Ni, and CZT:In + Sn, respectively. Results indicate that the addition of other dopants with In affects the type, nature, concentration (N t), and capture cross-section (σ) and hence trapping (t t) and de-trapping (t dt) times. Finally, the dopant-induced traps, their corresponding concentrations, and charge capture cross-section play an important role in the performance of radiation detectors, especially for devices that rely solely on electron transport.« less

Possible combinations of electronic data capture and randomization systems. principles and the realization with RANDI2 and OpenClinica.

PubMed

Schrimpf, D; Haag, M; Pilz, L R

2014-01-01

Clinical trials (CT) are in a wider sense experiments to prove and establish clinical benefit of treatments. Nowadays electronic data capture systems (EDCS) are used more often bringing a better data management and higher data quality into clinical practice. Also electronic systems for the randomization are used to assign the patients to the treatments. If the mentioned randomization system (RS) and EDCS are used, possibly identical data are collected in both, especially by stratified randomization. This separated data storage may lead to data inconsistency and in general data samples have to be aligned. The article discusses solutions to combine RS and EDCS. In detail one approach is realized and introduced. Different possible settings of combination of EDCS and RS are determined and the pros and cons for each solution are worked out. For the combination of two independent applications the necessary interfaces for the communication are defined. Thereby, existing standards are considered. An example realization is implemented with the help of open-source applications and state-of-the-art software development procedures. Three possibilities of separate usage or combination of EDCS and RS are presented and assessed: i) the complete independent usage of both systems; ii) realization of one system with both functions; and iii) two separate systems, which communicate via defined interfaces. In addition a realization of our preferred approach, the combination of both systems, is introduced using the open source tools RANDI2 and OpenClinica. The advantage of a flexible independent development of EDCS and RS is shown based on the fact that these tool are very different featured. In our opinion the combination of both systems via defined interfaces fulfills the requirements of randomization and electronic data capture and is feasible in practice. In addition, the use of such a setting can reduce the training costs and the error-prone duplicated data entry.

Development, implementation, and evaluation of a hybrid electronic medical record system specifically designed for a developing world surgical service.

PubMed

Laing, G L; Bruce, J L; Skinner, D L; Allorto, N L; Clarke, D L; Aldous, C

2014-06-01

The Pietermaritzburg Metropolitan Trauma Service previously successfully constructed and implemented an electronic surgical registry (ESR). This study reports on our attempts to expand and develop this concept into a multi-functional hybrid electronic medical record (HEMR) system for use in a tertiary level surgical service. This HEMR system was designed to incorporate the function and benefits of an ESR, an electronic medical record (EMR) system, and a clinical decision support system (CDSS). Formal ethical approval to maintain the HEMR system was obtained. Appropriate software was sourced to develop the project. The data model was designed as a relational database. Following the design and construction process, the HEMR file was launched on a secure server. This provided the benefits of access security and automated backups. A systematic training program was implemented for client training. The exercise of data capture was integrated into the process of clinical workflow, taking place at multiple points in time. Data were captured at the times of admission, operative intervention, endoscopic intervention, adverse events (morbidity), and the end of patient care (discharge, transfer, or death). A quarterly audit was performed 3 months after implementation of the HEMR system. The data were extracted and audited to assess their quality. A total of 1,114 patient entries were captured in the system. Compliance rates were in the order of 87-100 %, and client satisfaction rates were high. It is possible to construct and implement a unique, simple, cost-effective HEMR system in a developing world surgical service. This information system is unique in that it combines the discrete functions of an EMR system with an ESR and a CDSS. We identified a number of potential limitations and developed interventions to ameliorate them. This HEMR system provides the necessary platform for ongoing quality improvement programs and clinical research.

An analysis of point defects induced by In, Al, Ni, and Sn dopants in Bridgman-grown CdZnTe detectors and their influence on trapping of charge carriers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gul, R.; Roy, U. N.; James, R. B.

In this paper, we studied point defects induced in Bridgman-grown CdZnTe detectors doped with Indium (In), Aluminium (Al), Nickel (Ni), and Tin (Sn). Point defects associated with different dopants were observed, and these defects were analyzed in detail for their contributions to electron/hole (e/h) trapping. We also explored the correlations between the nature and abundance of the point defects with their influence on the resistivity, electron mobility-lifetime (μτ e) product, and electron trapping time. We used current-deep level transient spectroscopy to determine the energy, capture cross-section, and concentration of each trap. Furthermore, we used the data to determine the trappingmore » and de-trapping times for the charge carriers. In In-doped CdZnTe detectors, uncompensated Cd vacancies (V Cd -) were identified as a dominant trap. The V Cd - were almost compensated in detectors doped with Al, Ni, and Sn, in addition to co-doping with In. Dominant traps related to the dopant were found at E v + 0.36 eV and E v + 1.1 eV, E c + 76 meV and E v + 0.61 eV, E v + 36 meV and E v + 0.86 eV, E v + 0.52 eV and E c + 0.83 eV in CZT:In, CZT:In + Al, CZT:In + Ni, and CZT:In + Sn, respectively. Results indicate that the addition of other dopants with In affects the type, nature, concentration (N t), and capture cross-section (σ) and hence trapping (t t) and de-trapping (t dt) times. Finally, the dopant-induced traps, their corresponding concentrations, and charge capture cross-section play an important role in the performance of radiation detectors, especially for devices that rely solely on electron transport.« less

Cell Phone-Based System (Chaak) for Surveillance of Immatures of Dengue Virus Mosquito Vectors

PubMed Central

LOZANO–FUENTES, SAUL; WEDYAN, FADI; HERNANDEZ–GARCIA, EDGAR; SADHU, DEVADATTA; GHOSH, SUDIPTO; BIEMAN, JAMES M.; TEP-CHEL, DIANA; GARCÍA–REJÓN, JULIÁN E.; EISEN, LARS

2014-01-01

Capture of surveillance data on mobile devices and rapid transfer of such data from these devices into an electronic database or data management and decision support systems promote timely data analyses and public health response during disease outbreaks. Mobile data capture is used increasingly for malaria surveillance and holds great promise for surveillance of other neglected tropical diseases. We focused on mosquito-borne dengue, with the primary aims of: 1) developing and field-testing a cell phone-based system (called Chaak) for capture of data relating to the surveillance of the mosquito immature stages, and 2) assessing, in the dengue endemic setting of Mérida, México, the cost-effectiveness of this new technology versus paper-based data collection. Chaak includes a desktop component, where a manager selects premises to be surveyed for mosquito immatures, and a cell phone component, where the surveyor receives the assigned tasks and captures the data. Data collected on the cell phone can be transferred to a central database through different modes of transmission, including near-real time where data are transferred immediately (e.g., over the Internet) or by first storing data on the cell phone for future transmission. Spatial data are handled in a novel, semantically driven, geographic information system. Compared with a pen-and-paper-based method, use of Chaak improved the accuracy and increased the speed of data transcription into an electronic database. The cost-effectiveness of using the Chaak system will depend largely on the up-front cost of purchasing cell phones and the recurring cost of data transfer over a cellular network. PMID:23926788

75 FR 8115 - In the Matter of Certain Electronic Devices Having Image Capture or Display Functionality and...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-23

... 14157 (2009). The complainant named Eastman Kodak Company of Rochester, New York (``Kodak'') as the respondent. On December 16, 2009, LG and Kodak jointly moved to terminate the investigation based on a...

DETERMINATION OF PESTICIDES AND PCB'S IN INDUSTRIAL AND MUNICIPAL WASTEWATERS

EPA Science Inventory

Steps in the procedure for the analysis of 25 chlorinated pesticides and polychlorinated biphenyls were studied. Two gas chromatographic columns and two detectors (electron capture and Hall electrolytic conductivity) were evaluated. Extractions were performed with two solvents (d...

Fast calculator for X-ray emission due to Radiative Recombination and Radiative Electron Capture in relativistic heavy-ion atom collisions

NASA Astrophysics Data System (ADS)

Herdrich, M. O.; Weber, G.; Gumberidze, A.; Wu, Z. W.; Stöhlker, Th.

2017-10-01

In experiments with highly charged, fast heavy ions the Radiative Recombination (RR) and Radiative Electron Capture (REC) processes have significant cross sections in an energy range of up to a few GeV / u . They are some of the most important charge changing processes in collisions of heavy ions with atoms and electrons, leading to the emission of a photon along with the formation of the ground and excited atomic states. Hence, for the understanding and planning of experiments, in particular for X-ray spectroscopy studies, at accelerator ring facilities, such as FAIR, it is crucial to have a good knowledge of these cross sections and the associated radiation characteristics. In the frame of this work a fast calculator, named RECAL, for the RR and REC process is presented and its capabilities are demonstrated with the analysis of a recently conducted experiment at the Experimental Storage Ring (ESR) at the GSI Helmholtz Center for Heavy Ion Research in Darmstadt, Germany. A method is presented to determine unknown X-ray emission cross sections via normalization of the recorded spectra to REC cross sections calculated by RECAL.

Method and apparatus for detecting neutrons

DOEpatents

Perkins, R.W.; Reeder, P.L.; Wogman, N.A.; Warner, R.A.; Brite, D.W.; Richey, W.C.; Goldman, D.S.

1997-10-21

The instant invention is a method for making and using an apparatus for detecting neutrons. Scintillating optical fibers are fabricated by melting SiO{sub 2} with a thermal neutron capturing substance and a scintillating material in a reducing atmosphere. The melt is then drawn into fibers in an anoxic atmosphere. The fibers may then be coated and used directly in a neutron detection apparatus, or assembled into a geometrical array in a second, hydrogen-rich, scintillating material such as a polymer. Photons generated by interaction with thermal neutrons are trapped within the coated fibers and are directed to photoelectric converters. A measurable electronic signal is generated for each thermal neutron interaction within the fiber. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation. When the fibers are arranged in an array within a second scintillating material, photons generated by kinetic neutrons interacting with the second scintillating material and photons generated by thermal neutron capture within the fiber can both be directed to photoelectric converters. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation. 5 figs.

Morphological classification of bioaerosols from composting using scanning electron microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamer Vestlund, A.; FIRA International Ltd., Maxwell Road, Stevenage, Herts SG1 2EW; Al-Ashaab, R.

2014-07-15

Highlights: • Bioaerosols were captured using the filter method. • Bioaerosols were analysed using scanning electron microscope. • Bioaerosols were classified on the basis of morphology. • Single small cells were found more frequently than aggregates and larger cells. • Smaller cells may disperse further than heavier aggregate structures. - Abstract: This research classifies the physical morphology (form and structure) of bioaerosols emitted from open windrow composting. Aggregation state, shape and size of the particles captured are reported alongside the implications for bioaerosol dispersal after release. Bioaerosol sampling took place at a composting facility using personal air filter samplers. Samplesmore » were analysed using scanning electron microscopy. Particles were released mainly as small (<1 μm) single, spherical cells, followed by larger (>1 μm) single cells, with aggregates occurring in smaller proportions. Most aggregates consisted of clusters of 2–3 particles as opposed to chains, and were <10 μm in size. No cells were attached to soil debris or wood particles. These small single cells or small aggregates are more likely to disperse further downwind from source, and cell viability may be reduced due to increased exposure to environmental factors.« less

Method and apparatus for detecting neutrons

DOEpatents

Perkins, Richard W.; Reeder, Paul L.; Wogman, Ned A.; Warner, Ray A.; Brite, Daniel W.; Richey, Wayne C.; Goldman, Don S.

1997-01-01

The instant invention is a method for making and using an apparatus for detecting neutrons. Scintillating optical fibers are fabricated by melting SiO.sub.2 with a thermal neutron capturing substance and a scintillating material in a reducing atmosphere. The melt is then drawn into fibers in an anoxic atmosphere. The fibers may then be coated and used directly in a neutron detection apparatus, or assembled into a geometrical array in a second, hydrogen-rich, scintillating material such as a polymer. Photons generated by interaction with thermal neutrons are trapped within the coated fibers and are directed to photoelectric converters. A measurable electronic signal is generated for each thermal neutron interaction within the fiber. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation. When the fibers are arranged in an array within a second scintillating material, photons generated by kinetic neutrons interacting with the second scintillating material and photons generated by thermal neutron capture within the fiber can both be directed to photoelectric converters. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation.

Accelerator-based neutron source for boron neutron capture therapy (BNCT) and method

DOEpatents

Yoon, W.Y.; Jones, J.L.; Nigg, D.W.; Harker, Y.D.

1999-05-11

A source for boron neutron capture therapy (BNCT) comprises a body of photoneutron emitter that includes heavy water and is closely surrounded in heat-imparting relationship by target material; one or more electron linear accelerators for supplying electron radiation having energy of substantially 2 to 10 MeV and for impinging such radiation on the target material, whereby photoneutrons are produced and heat is absorbed from the target material by the body of photoneutron emitter. The heavy water is circulated through a cooling arrangement to remove heat. A tank, desirably cylindrical or spherical, contains the heavy water, and a desired number of the electron accelerators circumferentially surround the tank and the target material as preferably made up of thin plates of metallic tungsten. Neutrons generated within the tank are passed through a surrounding region containing neutron filtering and moderating materials and through neutron delimiting structure to produce a beam or beams of epithermal neutrons normally having a minimum flux intensity level of 1.0{times}10{sup 9} neutrons per square centimeter per second. Such beam or beams of epithermal neutrons are passed through gamma ray attenuating material to provide the required epithermal neutrons for BNCT use. 3 figs.

Accelerator-based neutron source for boron neutron capture therapy (BNCT) and method

DOEpatents

Yoon, Woo Y.; Jones, James L.; Nigg, David W.; Harker, Yale D.

1999-01-01

A source for boron neutron capture therapy (BNCT) comprises a body of photoneutron emitter that includes heavy water and is closely surrounded in heat-imparting relationship by target material; one or more electron linear accelerators for supplying electron radiation having energy of substantially 2 to 10 MeV and for impinging such radiation on the target material, whereby photoneutrons are produced and heat is absorbed from the target material by the body of photoneutron emitter. The heavy water is circulated through a cooling arrangement to remove heat. A tank, desirably cylindrical or spherical, contains the heavy water, and a desired number of the electron accelerators circumferentially surround the tank and the target material as preferably made up of thin plates of metallic tungsten. Neutrons generated within the tank are passed through a surrounding region containing neutron filtering and moderating materials and through neutron delimiting structure to produce a beam or beams of epithermal neutrons normally having a minimum flux intensity level of 1.0.times.10.sup.9 neutrons per square centimeter per second. Such beam or beams of epithermal neutrons are passed through gamma ray attenuating material to provide the required epithermal neutrons for BNCT use.

How to probe transverse magnetic anisotropy of a single-molecule magnet by electronic transport?

NASA Astrophysics Data System (ADS)

Misiorny, M.; Burzuri, E.; Gaudenzi, R.; Park, K.; Leijnse, M.; Wegewijs, M.; Paaske, J.; Cornia, A.; van der Zant, H.

We propose an approach for in-situ determination of the transverse magnetic anisotropy (TMA) of an individual molecule by electronic transport measurements, see Phys. Rev. B 91, 035442 (2015). We study a Fe4 single-molecule magnet (SMM) captured in a gateable junction, a unique tool for addressing the spin in different redox states of a molecule. We show that, due to mixing of the spin eigenstates of the SMM, the TMA significantly manifests itself in transport. We predict and experimentally observe the pronounced intensity modulation of the Coulomb peak amplitude with the magnetic field in the linear-response transport regime, from which the TMA parameter E can be estimated. Importantly, the method proposed here does not rely on the small induced tunnelling effects and, hence, works well at temperatures and electron tunnel broadenings by far exceeding the tunnel splittings and even E itself. We deduce that the TMA for a single Fe4 molecule captured in a junction is substantially larger than the bulk value. Work supported by the Polish Ministry of Science and Education as `Iuventus Plus' project (IP2014 030973) in years 2015-2016.

“Feathered” fractal surfaces to minimize secondary electron emission for a wide range of incident angles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swanson, Charles; Kaganovich, Igor D.

Complex structures on a material surface can significantly reduce the total secondary electron emission from that surface. The reduction occurs due to the capture of low-energy, true secondary electrons emitted at one point of the structure and intersecting another. We performed Monte Carlo calculations to demonstrate that fractal surfaces can reduce net secondary electron emission produced by the surface as compared to the flat surface. Specifically, we describe one surface, a “feathered” surface, which reduces the secondary electron emission yield more effectively than other previously considered configurations. Specifically, feathers grown onto a surface suppress secondary electron emission from shallow anglesmore » of incidence more effectively than velvet. Here, we find that, for the surface simulated, secondary electron emission yield remains below 20% of its un-suppressed value, even for shallow incident angles, where the velvet-only surface gives reduction factor of only 50%.« less

“Feathered” fractal surfaces to minimize secondary electron emission for a wide range of incident angles

DOE PAGES

Swanson, Charles; Kaganovich, Igor D.

2017-07-24

Complex structures on a material surface can significantly reduce the total secondary electron emission from that surface. The reduction occurs due to the capture of low-energy, true secondary electrons emitted at one point of the structure and intersecting another. We performed Monte Carlo calculations to demonstrate that fractal surfaces can reduce net secondary electron emission produced by the surface as compared to the flat surface. Specifically, we describe one surface, a “feathered” surface, which reduces the secondary electron emission yield more effectively than other previously considered configurations. Specifically, feathers grown onto a surface suppress secondary electron emission from shallow anglesmore » of incidence more effectively than velvet. Here, we find that, for the surface simulated, secondary electron emission yield remains below 20% of its un-suppressed value, even for shallow incident angles, where the velvet-only surface gives reduction factor of only 50%.« less

"Feathered" fractal surfaces to minimize secondary electron emission for a wide range of incident angles

NASA Astrophysics Data System (ADS)

Swanson, Charles; Kaganovich, Igor D.

2017-07-01

Complex structures on a material surface can significantly reduce the total secondary electron emission from that surface. The reduction occurs due to the capture of low-energy, true secondary electrons emitted at one point of the structure and intersecting another. We performed Monte Carlo calculations to demonstrate that fractal surfaces can reduce net secondary electron emission produced by the surface as compared to the flat surface. Specifically, we describe one surface, a "feathered" surface, which reduces the secondary electron emission yield more effectively than other previously considered configurations. Specifically, feathers grown onto a surface suppress secondary electron emission from shallow angles of incidence more effectively than velvet. We find that, for the surface simulated, secondary electron emission yield remains below 20% of its un-suppressed value, even for shallow incident angles, where the velvet-only surface gives reduction factor of only 50%.

Electron Attenuation Measurement using Cosmic Ray Muons at the MicroBooNE LArTPC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meddage, Varuna

2017-10-01

The MicroBooNE experiment at Fermilab uses liquid argon time projection chamber (LArTPC) technology to study neutrino interactions in argon. A fundamental requirement for LArTPCs is to achieve and maintain a low level of electronegative contaminants in the liquid to minimize the capture of drifting ionization electrons. The attenuation time for the drifting electrons should be long compared to the maximum drift time, so that the signals from particle tracks that generate ionization electrons with long drift paths can be detected efficiently. In this talk we present MicroBooNE measurement of electron attenuation using cosmic ray muons. The result yields a minimummore » electron 1/e lifetime of 18 ms under typical operating conditions, which is long compared to the maximum drift time of 2.3 ms.« less

Astronauts Thornton & Akers on HST photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-05

S61-E-012 (5 Dec 1993) --- This view of astronauts Kathryn C. Thornton (top) and Thomas D. Akers working on the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. Thornton, anchored to the end of the Remote Manipulator System (RMS) arm, is teaming with Akers to install the +V2 Solar Array Panel as a replacement for the original one removed earlier. Akers uses tethers and a foot restraint to remain in position for the task. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Astronauts Thornton & Akers on HST photographed by Electronic Still Camera

NASA Image and Video Library

1993-12-05

S61-E-014 (5 Dec 1993) --- This view of astronauts Kathryn C. Thornton (bottom) and Thomas D. Akers working on the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and down linked to ground controllers soon afterward. Thornton, anchored to the end of the Remote Manipulator System (RMS) arm, is teaming with Akers to install the +V2 Solar Array Panel as a replacement for the original one removed earlier. Akers uses tethers and a foot restraint to remain in position for the task. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

Ultrafast above-threshold dynamics of the radical anion of a prototypical quinone electron-acceptor.

PubMed

Horke, Daniel A; Li, Quansong; Blancafort, Lluís; Verlet, Jan R R

2013-08-01

Quinones feature prominently as electron acceptors in nature. Their electron-transfer reactions are often highly exergonic, for which Marcus theory predicts reduced electron-transfer rates because of a free-energy barrier that occurs in the inverted region. However, the electron-transfer kinetics that involve quinones can appear barrierless. Here, we consider the intrinsic properties of the para-benzoquinone radical anion, which serves as the prototypical electron-transfer reaction product involving a quinone-based acceptor. Using time-resolved photoelectron spectroscopy and ab initio calculations, we show that excitation at 400 and 480 nm yields excited states that are unbound with respect to electron loss. These excited states are shown to decay on a sub-40 fs timescale through a series of conical intersections with lower-lying excited states, ultimately to form the ground anionic state and avoid autodetachment. From an isolated electron-acceptor perspective, this ultrafast stabilization mechanism accounts for the ability of para-benzoquinone to capture and retain electrons.

S-factor for radiative capture reactions for light nuclei at astrophysical energies

NASA Astrophysics Data System (ADS)

Ghasemi, Reza; Sadeghi, Hossein

2018-06-01

The astrophysical S-factors of thermonuclear reactions, including radiative capture reactions and their analysis in the frame of different theoretical models, are the main source of nuclear processes. We have done research on the radiative capture reactions importance in the framework of a potential model. Investigation of the reactions in the astrophysical energies is of great interest in the aspect of astrophysics and nuclear physics for developing correct models of burning and evolution of stars. The experimental measurements are very difficult and impossible because of these reactions occurrence at low-energies. In this paper we do a calculation on radiative capture astrophysical S-factors for nuclei in the mass region A < 17. We calculate the astrophysical factor for the dipole electronic transition E1 and magnetic dipole transition M1 and electric quadrupole transition E2 by using the M3Y potential for non-resonances and resonances captures. Then we have got the parameter of a central part and spin-orbit part of M3Y potential and spectroscopic factor for reaction channels. For the astrophysical S-factor of this article the good agreement is achieved In comparison with experimental data and other theoretical methods.

Association Between Real-time Electronic Injury Surveillance Applications and Clinical Documentation and Data Acquisition in a South African Trauma Center.

PubMed

Zargaran, Eiman; Spence, Richard; Adolph, Lauren; Nicol, Andrew; Schuurman, Nadine; Navsaria, Pradeep; Ramsey, Damon; Hameed, S Morad

2018-03-14

Collection and analysis of up-to-date and accurate injury surveillance data are a key step in the maturation of trauma systems. Trauma registries have proven to be difficult to establish in low- and middle-income countries owing to the burden of trauma volume, cost, and complexity. To determine whether an electronic trauma health record (eTHR) used by physicians can serve as simultaneous clinical documentation and data acquisition tools. This 2-part quality improvement study included (1) preimplementation and postimplementation eTHR study with assessments of satisfaction by 41 trauma physicians, time to completion, and quality of data collected comparing paper and electronic charting; and (2) prospective ecologic study describing the burden of trauma seen at a Level I trauma center, using real-time data collected by the eTHR on consecutive patients during a 12-month study period. The study was conducted from October 1, 2010, to September 30, 2011, at Groote Schuur Hospital, Cape Town, South Africa. Data analysis was performed from October 15, 2011, to January 15, 2013. The primary outcome of part 1 was data field competition rates of pertinent trauma registry items obtained through electronic or paper documentation. The main measures of part 2 were to identify risk factors to trauma in Cape Town and quality indicators recommended for trauma system evaluation at Groote Schuur Hospital. The 41 physicians included in the study found the electronic patient documentation to be more efficient and preferable. A total of 11 612 trauma presentations were accurately documented and promptly analyzed. Fields relevant to injury surveillance in the eTHR (n = 11 612) had statistically significant higher completion rates compared with paper records (n = 9236) (for all comparisons, P < .001). The eTHR successfully captured quality indicators recommended for trauma system evaluation which were previously challenging to collect in a timely and accurate manner. Of the 11 612 patient admissions over the study period, injury location was captured 11 075 times (95.4%), injury mechanism 11 135 times (95.9%), systolic blood pressure 11 106 times (95.6%), and Glasgow Coma Scale 11 140 times (95.9%). These fields were successfully captured with statistically higher rates than previous paper documentation. Epidemiologic analysis confirmed a heavy burden of violence-related injury (51.8% of all injuries) and motor vehicle crash injuries (14.3% of all injuries). Mapping analysis demonstrated clusters of injuries originating mainly from vulnerable and low-income neighborhoods and their respective referring trauma facilities, Mitchell's Plain Hospital (734 [10.1%]), Guguletu Community Health Center (654 [9.0%]), and New Somerset Hospital (400 [5.5%]). Accurate capture and simultaneous analysis of trauma data in low-resource trauma settings are feasible through the integration of surveillance into clinical workflow and the timely analysis of electronic data.

Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013

NASA Astrophysics Data System (ADS)

Paral, J.; Hudson, M. K.; Kress, B. T.; Wiltberger, M. J.; Wygant, J. R.; Singer, H. J.

2015-08-01

Coronal mass ejection (CME)-shock compression of the dayside magnetopause has been observed to cause both prompt enhancement of radiation belt electron flux due to inward radial transport of electrons conserving their first adiabatic invariant and prompt losses which at times entirely eliminate the outer zone. Recent numerical studies suggest that enhanced ultra-low frequency (ULF) wave activity is necessary to explain electron losses deeper inside the magnetosphere than magnetopause incursion following CME-shock arrival. A combination of radial transport and magnetopause shadowing can account for losses observed at radial distances into L = 4.5, well within the computed magnetopause location. We compare ULF wave power from the Electric Field and Waves (EFW) electric field instrument on the Van Allen Probes for the 8 October 2013 storm with ULF wave power simulated using the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamic (MHD) magnetospheric simulation code coupled to the Rice Convection Model (RCM). Two other storms with strong magnetopause compression, 8-9 October 2012 and 17-18 March 2013, are also examined. We show that the global MHD model captures the azimuthal magnetosonic impulse propagation speed and amplitude observed by the Van Allen Probes which is responsible for prompt acceleration at MeV energies reported for the 8 October 2013 storm. The simulation also captures the ULF wave power in the azimuthal component of the electric field, responsible for acceleration and radial transport of electrons, at frequencies comparable to the electron drift period. This electric field impulse has been shown to explain observations in related studies (Foster et al., 2015) of electron acceleration and drift phase bunching by the Energetic Particle, Composition, and Thermal Plasma Suite (ECT) instrument on the Van Allen Probes.

Negative ion electron impact studies of arsenic trihalides: AsF/sub 3/, AsCl/sub 3/, and AsBr/sub 3/

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pabst, R.E.; Bennett, S.L.; Margrave, J.L.

1976-08-15

Low energy eleAsF/sup 2/-tron impact of AsF/sub 3/, AsCl/sub 3/, and AsBr/sub 3/ gases gave many ions by dissociative resonance capture. Appearance potentials have been determined by deconvolution of the capture curves, and translational energies of the majority of the ions have been measured through the resonance processes. The X/sup -/ ions are formed along with electronically excited neutral AsX/sub 2/, and the results allow the electronic transition energies to be determined: 7.3, 4.3, and 2.6 eV for AsF/sub 2/, AsCl/sup 2/, and AsBr/sup 2/, respectively. From the processes giving AsX/sup -2/+X, the experimental data allow the heats of formationmore » of the negative ions ..delta..H/subf/(AsX/sup -2/) to be derived: -129.7, -65.3, and -72.5 kcal mole/sup -1/ for AsF/sup -2/, AsCl/sup -2/, and AsBr/sup -2/, respectively. The ions AsCl/sup -/ and AsBr/sup -/ appear to be formed along with electronically excited X/sub 2/ neutral: ..delta..H/subf/(AsCl/sup -/) =-2.2 kcal mole/sup -1/ and ..delta..H/subf/(AsBr/sup -/) =1.7 kcal mole/sup -1/ are derived. The ions X/sup -2/ appear to be formed with electronically excited AsX neutral, allowing the electronic transition energies to be derived: E*/sub el/(AsBr) >0.6 eV and E*/sub el/(AsCl) =2.5 eV. (AIP)« less

GC/HRSIR as a Complementary Technique to GC/ECNIMS

EPA Science Inventory

Gas chromatography/electron capture negative ion mass spectrometry (GC/ECNIMS) is a highly selective and sensitive technique for the analysis of appropriate analytes in complex matrices. Its major drawback is often the lack of fragmentation indicative of structure that can be use...

DEMONSTRATION BULLETIN: FIELD ANALYTICAL SCREENING PROGRAM: PCB METHOD - U.S. ENVIRONMENTAL PROTECTION AGENCY

EPA Science Inventory

The field analytical screening program (FASP) polychlorinated biphenyl (PCB) method uses a temperature-programmable gas chromatograph (GC) equipped with an electron capture detector (ECD) to identify and quantify PCBs. Gas chromatography is an EPA-approved method for determi...

Technique for evaluation of the strong potential Born approximation for electron capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sil, N.C.; McGuire, J.H.

1985-04-01

A technique is presented for evaluating differential cross sections in the strong potential Born (SPB) approximation. Our final expression is expressed as a finite sum of one-dimensional integrals, expressible as a finite sum of derivatives of hypergeometric functions.

View of the Cupola RWS taken with Fish-Eye Lens

NASA Image and Video Library

2010-05-08

ISS023-E-039983 (8 May 2010) --- A fish-eye lens attached to an electronic still camera was used by an Expedition 23 crew member to capture this image of the robotic workstation in the Cupola of the International Space Station.

Get It Right First Time: A Beginner's Guide to Document Management.

ERIC Educational Resources Information Center

Hayes, Mike

1997-01-01

Document management (DM) systems capture, store, index, retrieve, route, distribute, and archive information in organizations. Discusses "passive" electronic libraries and "active" systems; characteristics of effective systems; implementing a system; fitting a new system to an existing infrastructure; budgets; system…

FIELD ANALYTICAL SCREENING PROGRAM: PCP METHOD - INNOVATIVE TECHNOLOGY EVALUATION REPORT

EPA Science Inventory

The Field Analytical Screening Program (FASP) pentachlorophenol (PCP) method uses a gas chromatograph (GC) equipped with a megabore capillary column and flame ionization detector (FID) and electron capture detector (ECD) to identify and quantify PCP. The FASP PCP method is design...

AVOIDING PITFALLS IN THE DETERMINATION OF HALOCARBOXYLIC ACIDS: THE PHOTOCHEMISTRY OF METHYLATION

EPA Science Inventory

Haloethanoic (haloacetic) acids are formed during chlorination of drinking water and are regulated by the Environmental Protection Agency (EPA). These compounds are normally quantified by gas chromatography with electron capture detection (GC-ECD) ad the methyl esters. EPA Meth...

Imaging mass spectrometry tackles interfacial challenges in electrochemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Xiao-Ying

Electrochemistry has played a significant role in many research fields. Owing to its sensitivity and selectivity, in situ electroanalysis has been widely used as a fast and economical means for achieving outstanding results. Although many spectroscopic techniques have been used in electrochemistry, the challenges to capture short-lived intermediate species as a result of electron transfer in the buried solid electrode and electrolyte solution interface remains a grand challenge. In situ imaging mass spectrometry (IMS) recently has been extended to capture transient species in electrochemistry. This review intends to summarize newest development of IMS and its applications in advancing fundamental electrochemistry.

Dynamic CDM strategies in an EHR environment.

PubMed

Bieker, Michael; Bailey, Spencer

2012-02-01

A dynamic charge description master (CDM) integrates information from clinical ancillary systems into the charge-capture process, so an organization can reduce its reliance on the patient accounting system as the sole source of billing information. By leveraging the information from electronic ancillary systems, providers can eliminate the need for paper charge-capture forms and see increased accuracy and efficiency in the maintenance of billing information. Before embarking on a dynamic CDM strategy, organizations should first determine their goals for implementing an EHR system, include revenue cycle leaders on the EHR implementation team, and carefully weigh the pros and cons of CDM design decisions.

Isolation of a Diatom Frustule Fragment from the Lower Stratosphere (22-27Km)-EVIDENCE for a Cosmic Origin

NASA Astrophysics Data System (ADS)

Wainwright, Milton; Rose, Christopher E.; Baker, Alexander J.; Briston, J. K.; Wickramasinghe, N. Chandra

2013-03-01

Sampling of the stratosphere at heights between 22 and 27 km was carried out in the UK on 31st July 2013 using balloon-borne equipment carrying aseptically clean electron microscope stubs onto which aerosols were directly captured. The experiment revealed the presence of a diatom frustule captured from a height of >25km. On account of the very short residence time of particles of diatom size and mass at these heights, we argue for its incidence from space, with a probable origin in the watery environment of a comet.

β-relaxation related bright bands in thin film metallic glasses: Localized percolation of flow units captured via transmission electron microscope

NASA Astrophysics Data System (ADS)

Chen, Z. Q.; Huang, P.; Xu, K. W.; Wang, F.; Lu, T. J.

2016-12-01

We report that β-relaxation of amorphous NiW alloy film was effectively enhanced by adding two thin crystalline layers into the amorphous layer. Correspondingly, more bright bands, i.e., nano shear bands, were captured in the amorphous layer, which experienced more pronounced β-relaxations. Based on the potential energy landscape theory, the bright band was proposed to be the localized percolation of flow units corresponding to β-relaxation. Our findings may help connecting experimentally β-relaxation with flow units and shed light on the microstructure origin of β-relaxation.

Astronaut Health Participant Summary Application

NASA Technical Reports Server (NTRS)

Johnson, Kathy; Krog, Ralph; Rodriguez, Seth; Wear, Mary; Volpe, Robert; Trevino, Gina; Eudy, Deborah; Parisian, Diane

2011-01-01

The Longitudinal Study of Astronaut Health (LSAH) Participant Summary software captures data based on a custom information model designed to gather all relevant, discrete medical events for its study participants. This software provides a summarized view of the study participant s entire medical record. The manual collapsing of all the data in a participant s medical record into a summarized form eliminates redundancy, and allows for the capture of entire medical events. The coding tool could be incorporated into commercial electronic medical record software for use in areas like public health surveillance, hospital systems, clinics, and medical research programs.

Mass Measurement of 56Sc Reveals a Small A=56 Odd-Even Mass Staggering, Implying a Cooler Accreted Neutron Star Crust

DOE PAGES

Meisel, Z.; George, S.; Ahn, S.; ...

2015-10-16

We present the mass excesses of 52-57Sc, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The masses of 56Sc and 57Sc were determined for the first time with atomic mass excesses of -24.85(59)((+0)(-54)) MeV and -21.0(1.3) MeV, respectively, where the asymmetric uncertainty for 56Sc was included due to possible contamination from a long-lived isomer. The 56Sc mass indicates a small odd-even mass staggering in the A = 56 mass chain towards the neutron drip line, significantly deviating from trends predicted by the global FRDM mass model and favoring trends predicted bymore » the UNEDF0 and UNEDF1 density functional calculations. Together with new shell-model calculations of the electron-capture strength function of 56Sc, our results strongly reduce uncertainties in model calculations of the heating and cooling at the 56Ti electron-capture layer in the outer crust of accreting neutron stars. We find that, in contrast to previous studies, neither strong neutrino cooling nor strong heating occurs in this layer. We conclude that Urca cooling in the outer crusts of accreting neutron stars that exhibit superbursts or high temperature steady-state burning, which are predicted to be rich in A approximate to 56 nuclei, is considerably weaker than predicted. Urca cooling must instead be dominated by electron capture on the small amounts of adjacent odd-A nuclei contained in the superburst and high temperature steady-state burning ashes. This may explain the absence of strong crust Urca cooling inferred from the observed cooling light curve of the transiently accreting x-ray source MAXI J0556-332.« less

Mass Measurement of 56Sc Reveals a Small A =56 Odd-Even Mass Staggering, Implying a Cooler Accreted Neutron Star Crust

NASA Astrophysics Data System (ADS)

Meisel, Z.; George, S.; Ahn, S.; Bazin, D.; Brown, B. A.; Browne, J.; Carpino, J. F.; Chung, H.; Cole, A. L.; Cyburt, R. H.; Estradé, A.; Famiano, M.; Gade, A.; Langer, C.; Matoš, M.; Mittig, W.; Montes, F.; Morrissey, D. J.; Pereira, J.; Schatz, H.; Schatz, J.; Scott, M.; Shapira, D.; Smith, K.; Stevens, J.; Tan, W.; Tarasov, O.; Towers, S.; Wimmer, K.; Winkelbauer, J. R.; Yurkon, J.; Zegers, R. G. T.

2015-10-01

We present the mass excesses of 52-57Sc, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The masses of 56Sc and 57Sc were determined for the first time with atomic mass excesses of -24.85 (59 )(-54+0) MeV and -21.0 (1.3 ) MeV , respectively, where the asymmetric uncertainty for 56Sc was included due to possible contamination from a long-lived isomer. The 56Sc mass indicates a small odd-even mass staggering in the A =56 mass chain towards the neutron drip line, significantly deviating from trends predicted by the global FRDM mass model and favoring trends predicted by the UNEDF0 and UNEDF1 density functional calculations. Together with new shell-model calculations of the electron-capture strength function of 56Sc, our results strongly reduce uncertainties in model calculations of the heating and cooling at the 56Ti electron-capture layer in the outer crust of accreting neutron stars. We find that, in contrast to previous studies, neither strong neutrino cooling nor strong heating occurs in this layer. We conclude that Urca cooling in the outer crusts of accreting neutron stars that exhibit superbursts or high temperature steady-state burning, which are predicted to be rich in A ≈56 nuclei, is considerably weaker than predicted. Urca cooling must instead be dominated by electron capture on the small amounts of adjacent odd-A nuclei contained in the superburst and high temperature steady-state burning ashes. This may explain the absence of strong crust Urca cooling inferred from the observed cooling light curve of the transiently accreting x-ray source MAXI J0556-332.

β-Decay half-lives and nuclear structure of exotic proton-rich waiting point nuclei under rp-process conditions

NASA Astrophysics Data System (ADS)

Nabi, Jameel-Un; Böyükata, Mahmut

2016-03-01

We investigate even-even nuclei in the A ∼ 70 mass region within the framework of the proton-neutron quasi-particle random phase approximation (pn-QRPA) and the interacting boson model-1 (IBM-1). Our work includes calculation of the energy spectra and the potential energy surfaces V (β , γ) of Zn, Ge, Se, Kr and Sr nuclei with the same proton and neutron number, N = Z. The parametrization of the IBM-1 Hamiltonian was performed for the calculation of the energy levels in the ground state bands. Geometric shape of the nuclei was predicted by plotting the potential energy surfaces V (β , γ) obtained from the IBM-1 Hamiltonian in the classical limit. The pn-QRPA model was later used to compute half-lives of the neutron-deficient nuclei which were found to be in very good agreement with the measured ones. The pn-QRPA model was also used to calculate the Gamow-Teller strength distributions and was found to be in decent agreement with the measured data. We further calculate the electron capture and positron decay rates for these N = Z waiting point (WP) nuclei in the stellar environment employing the pn-QRPA model. For the rp-process conditions, our total weak rates are within a factor two compared with the Skyrme HF +BCS +QRPA calculation. All calculated electron capture rates are comparable to the competing positron decay rates under rp-process conditions. Our study confirms the finding that electron capture rates form an integral part of the weak rates under rp-process conditions and should not be neglected in the nuclear network calculations.

Nuclear structure properties and stellar weak rates for 76Se: Unblocking of the Gamow Teller strength

NASA Astrophysics Data System (ADS)

Nabi, Jameel-Un; Ishfaq, Mavra; Böyükata, Mahmut; Riaz, Muhammad

2017-10-01

At finite temperatures (≥ 107K), 76Se is abundant in the core of massive stars and electron capture on 76Se has a consequential role to play in the dynamics of core-collapse. The present work may be classified into two main categories. In the first phase we study the nuclear structure properties of 76Se using the interacting boson model-1 (IBM-1). The IBM-1 investigations include the energy levels, B (E 2) values and the prediction of the geometry. We performed the extended consistent-Q formalism (ECQF) calculation and later the triaxial formalism calculation (constructed by adding the cubic term to the ECQF). The geometry of 76Se can be envisioned within the formalism of the potential energy surface based on the classical limit of IBM-1 model. In the second phase, we reconfirm the unblocking of the Gamow-Teller (GT) strength in 76Se (a test case for nuclei having N > 40 and Z < 40). Using the deformed pn-QRPA model we calculate GT transitions, stellar electron capture cross section (within the limit of low momentum transfer) and stellar weak rates for 76Se. The distinguishing feature of our calculation is a state-by-state evaluation of stellar weak rates in a fully microscopic fashion. Results are compared with experimental data and previous calculations. The calculated GT distribution fulfills the Ikeda sum rule. Rates for β-delayed neutrons and emission probabilities are also calculated. Our study suggests that at high stellar temperatures and low densities, the β+-decay on 76Se should not be neglected and needs to be taken into consideration along with electron capture rates for simulation of presupernova evolution of massive stars.

Systems and methods for optically measuring properties of hydrocarbon fuel gases

DOEpatents

Adler-Golden, S.; Bernstein, L.S.; Bien, F.; Gersh, M.E.; Goldstein, N.

1998-10-13

A system and method for optical interrogation and measurement of a hydrocarbon fuel gas includes a light source generating light at near-visible wavelengths. A cell containing the gas is optically coupled to the light source which is in turn partially transmitted by the sample. A spectrometer disperses the transmitted light and captures an image thereof. The image is captured by a low-cost silicon-based two-dimensional CCD array. The captured spectral image is processed by electronics for determining energy or BTU content and composition of the gas. The innovative optical approach provides a relatively inexpensive, durable, maintenance-free sensor and method which is reliable in the field and relatively simple to calibrate. In view of the above, accurate monitoring is possible at a plurality of locations along the distribution chain leading to more efficient distribution. 14 figs.

Gd@C82 metallofullerenes for neutron capture therapy—fullerene solubilization by poly(ethylene glycol)-block-poly(2-(N, N-diethylamino)ethyl methacrylate) and resultant efficacy in vitro

PubMed Central

Horiguchi, Yukichi; Kudo, Shinpei; Nagasaki, Yukio

2011-01-01

Poly(ethylene glycol)-block-poly(2-(N,N-diethylamino)ethyl methacrylate) (PEG-b-PAMA) was found to solubilize fullerenes such as C60, and this technique was applied to metallofullerenes. Gd@C82 was easily dissolved in water in the presence of PEG-b-PAMA without any covalent derivatization, forming a transparent complex about 20–30 nm in diameter. Low cytotoxicity was confirmed in vitro. Neutron irradiation of cultured cells (colon-26 adenocarcinoma) with Gd@C82-PEG-b-PAMA-complexed nanoparticles showed effective cytotoxicity, indicating the effective emission of gamma rays and internal conversion electrons produced from the neutron capture reaction of Gd. This result suggests a potentially valuable approach to gadolinium-based neutron capture therapy. PMID:27877415

Systems and methods for optically measuring properties of hydrocarbon fuel gases

DOEpatents

Adler-Golden, Steven; Bernstein, Lawrence S.; Bien, Fritz; Gersh, Michael E.; Goldstein, Neil

1998-10-13

A system and method for optical interrogation and measurement of a hydrocarbon fuel gas includes a light source generating light at near-visible wavelengths. A cell containing the gas is optically coupled to the light source which is in turn partially transmitted by the sample. A spectrometer disperses the transmitted light and captures an image thereof. The image is captured by a low-cost silicon-based two-dimensional CCD array. The captured spectral image is processed by electronics for determining energy or BTU content and composition of the gas. The innovative optical approach provides a relatively inexpensive, durable, maintenance-free sensor and method which is reliable in the field and relatively simple to calibrate. In view of the above, accurate monitoring is possible at a plurality of locations along the distribution chain leading to more efficient distribution.

Effects of nanopillar array diameter and spacing on cancer cell capture and cell behaviors

NASA Astrophysics Data System (ADS)

Wang, Shunqiang; Wan, Yuan; Liu, Yaling

2014-10-01

While substrates with nanopillars (NPs) have emerged as promising platforms for isolation of circulating tumor cells (CTCs), the influence of diameter and spacing of NPs on CTC capture is still unclear. In this paper, CTC-capture yield and cell behaviors have been investigated by using antibody functionalized NPs of various diameters (120-1100 nm) and spacings (35-800 nm). The results show a linear relationship between the cell capture yield and effective contact area of NP substrates where a NP array of small diameter and reasonable spacing is preferred; however, spacing that is too small or too large adversely impairs the capture efficiency and specificity, respectively. In addition, the formation of pseudopodia between captured cells and the substrate is found to be dependent not only on cell adhesion status but also on elution strength and shear direction. These findings provide essential guidance in designing NP substrates for more efficient capture of CTCs and manipulation of cytomorphology in future.While substrates with nanopillars (NPs) have emerged as promising platforms for isolation of circulating tumor cells (CTCs), the influence of diameter and spacing of NPs on CTC capture is still unclear. In this paper, CTC-capture yield and cell behaviors have been investigated by using antibody functionalized NPs of various diameters (120-1100 nm) and spacings (35-800 nm). The results show a linear relationship between the cell capture yield and effective contact area of NP substrates where a NP array of small diameter and reasonable spacing is preferred; however, spacing that is too small or too large adversely impairs the capture efficiency and specificity, respectively. In addition, the formation of pseudopodia between captured cells and the substrate is found to be dependent not only on cell adhesion status but also on elution strength and shear direction. These findings provide essential guidance in designing NP substrates for more efficient capture of CTCs and manipulation of cytomorphology in future. Electronic supplementary information (ESI) available: Additional details about calculation of maximal displacement of an individual NP; additional study of substrate wettability through Cassie's Law; additional details about selection of incubation time and shaking speeds. See DOI: 10.1039/c4nr02854f

S2O - A software tool for integrating research data from general purpose statistic software into electronic data capture systems.

PubMed

Bruland, Philipp; Dugas, Martin

2017-01-07

Data capture for clinical registries or pilot studies is often performed in spreadsheet-based applications like Microsoft Excel or IBM SPSS. Usually, data is transferred into statistic software, such as SAS, R or IBM SPSS Statistics, for analyses afterwards. Spreadsheet-based solutions suffer from several drawbacks: It is generally not possible to ensure a sufficient right and role management; it is not traced who has changed data when and why. Therefore, such systems are not able to comply with regulatory requirements for electronic data capture in clinical trials. In contrast, Electronic Data Capture (EDC) software enables a reliable, secure and auditable collection of data. In this regard, most EDC vendors support the CDISC ODM standard to define, communicate and archive clinical trial meta- and patient data. Advantages of EDC systems are support for multi-user and multicenter clinical trials as well as auditable data. Migration from spreadsheet based data collection to EDC systems is labor-intensive and time-consuming at present. Hence, the objectives of this research work are to develop a mapping model and implement a converter between the IBM SPSS and CDISC ODM standard and to evaluate this approach regarding syntactic and semantic correctness. A mapping model between IBM SPSS and CDISC ODM data structures was developed. SPSS variables and patient values can be mapped and converted into ODM. Statistical and display attributes from SPSS are not corresponding to any ODM elements; study related ODM elements are not available in SPSS. The S2O converting tool was implemented as command-line-tool using the SPSS internal Java plugin. Syntactic and semantic correctness was validated with different ODM tools and reverse transformation from ODM into SPSS format. Clinical data values were also successfully transformed into the ODM structure. Transformation between the spreadsheet format IBM SPSS and the ODM standard for definition and exchange of trial data is feasible. S2O facilitates migration from Excel- or SPSS-based data collections towards reliable EDC systems. Thereby, advantages of EDC systems like reliable software architecture for secure and traceable data collection and particularly compliance with regulatory requirements are achievable.

Comparison of electronic data capture (EDC) with the standard data capture method for clinical trial data.

PubMed

Walther, Brigitte; Hossin, Safayet; Townend, John; Abernethy, Neil; Parker, David; Jeffries, David

2011-01-01

Traditionally, clinical research studies rely on collecting data with case report forms, which are subsequently entered into a database to create electronic records. Although well established, this method is time-consuming and error-prone. This study compares four electronic data capture (EDC) methods with the conventional approach with respect to duration of data capture and accuracy. It was performed in a West African setting, where clinical trials involve data collection from urban, rural and often remote locations. Three types of commonly available EDC tools were assessed in face-to-face interviews; netbook, PDA, and tablet PC. EDC performance during telephone interviews via mobile phone was evaluated as a fourth method. The Graeco Latin square study design allowed comparison of all four methods to standard paper-based recording followed by data double entry while controlling simultaneously for possible confounding factors such as interview order, interviewer and interviewee. Over a study period of three weeks the error rates decreased considerably for all EDC methods. In the last week of the study the data accuracy for the netbook (5.1%, CI95%: 3.5-7.2%) and the tablet PC (5.2%, CI95%: 3.7-7.4%) was not significantly different from the accuracy of the conventional paper-based method (3.6%, CI95%: 2.2-5.5%), but error rates for the PDA (7.9%, CI95%: 6.0-10.5%) and telephone (6.3%, CI95% 4.6-8.6%) remained significantly higher. While EDC-interviews take slightly longer, data become readily available after download, making EDC more time effective. Free text and date fields were associated with higher error rates than numerical, single select and skip fields. EDC solutions have the potential to produce similar data accuracy compared to paper-based methods. Given the considerable reduction in the time from data collection to database lock, EDC holds the promise to reduce research-associated costs. However, the successful implementation of EDC requires adjustment of work processes and reallocation of resources.

Comparison of Electronic Data Capture (EDC) with the Standard Data Capture Method for Clinical Trial Data

PubMed Central

Walther, Brigitte; Hossin, Safayet; Townend, John; Abernethy, Neil; Parker, David; Jeffries, David

2011-01-01

Background Traditionally, clinical research studies rely on collecting data with case report forms, which are subsequently entered into a database to create electronic records. Although well established, this method is time-consuming and error-prone. This study compares four electronic data capture (EDC) methods with the conventional approach with respect to duration of data capture and accuracy. It was performed in a West African setting, where clinical trials involve data collection from urban, rural and often remote locations. Methodology/Principal Findings Three types of commonly available EDC tools were assessed in face-to-face interviews; netbook, PDA, and tablet PC. EDC performance during telephone interviews via mobile phone was evaluated as a fourth method. The Graeco Latin square study design allowed comparison of all four methods to standard paper-based recording followed by data double entry while controlling simultaneously for possible confounding factors such as interview order, interviewer and interviewee. Over a study period of three weeks the error rates decreased considerably for all EDC methods. In the last week of the study the data accuracy for the netbook (5.1%, CI95%: 3.5–7.2%) and the tablet PC (5.2%, CI95%: 3.7–7.4%) was not significantly different from the accuracy of the conventional paper-based method (3.6%, CI95%: 2.2–5.5%), but error rates for the PDA (7.9%, CI95%: 6.0–10.5%) and telephone (6.3%, CI95% 4.6–8.6%) remained significantly higher. While EDC-interviews take slightly longer, data become readily available after download, making EDC more time effective. Free text and date fields were associated with higher error rates than numerical, single select and skip fields. Conclusions EDC solutions have the potential to produce similar data accuracy compared to paper-based methods. Given the considerable reduction in the time from data collection to database lock, EDC holds the promise to reduce research-associated costs. However, the successful implementation of EDC requires adjustment of work processes and reallocation of resources. PMID:21966505

Negative ion productions in high velocity collision between small carbon clusters and Helium atom target

NASA Astrophysics Data System (ADS)

M, Chabot; K, Béroff; T, Pino; G, Féraud; N, Dothi; Padellec A, Le; G, Martinet; S, Bouneau; Y, Carpentier

2012-11-01

We measured absolute double capture cross section of Cn+ ions (n=1,5) colliding, at 2.3 and 2.6 a.u velocities, with an Helium target atom and the branching ratios of fragmentation of the so formed electronically excited anions Cn-*. We also measured absolute cross section for the electronic attachment on neutral Cn clusters colliding at same velocities with He atom. This is to our knowledge the first measurement of neutral-neutral charge exchange in high velocity collision.

Multiple electron processes of He and Ne by proton impact

NASA Astrophysics Data System (ADS)

Terekhin, Pavel Nikolaevich; Montenegro, Pablo; Quinto, Michele; Monti, Juan; Fojon, Omar; Rivarola, Roberto

2016-05-01

A detailed investigation of multiple electron processes (single and multiple ionization, single capture, transfer-ionization) of He and Ne is presented for proton impact at intermediate and high collision energies. Exclusive absolute cross sections for these processes have been obtained by calculation of transition probabilities in the independent electron and independent event models as a function of impact parameter in the framework of the continuum distorted wave-eikonal initial state theory. A binomial analysis is employed to calculate exclusive probabilities. The comparison with available theoretical and experimental results shows that exclusive probabilities are needed for a reliable description of the experimental data. The developed approach can be used for obtaining the input database for modeling multiple electron processes of charged particles passing through the matter.

RF-driven ion source with a back-streaming electron dump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwan, Joe; Ji, Qing

A novel ion source is described having an improved lifetime. The ion source, in one embodiment, is a proton source, including an external RF antenna mounted to an RF window. To prevent backstreaming electrons formed in the beam column from striking the RF window, a back streaming electron dump is provided, which in one embodiment is formed of a cylindrical tube, open at one end to the ion source chamber and capped at its other end by a metal plug. The plug, maintained at the same electrical potential as the source, captures these backstreaming electrons, and thus prevents localized heatingmore » of the window, which due to said heating, might otherwise cause window damage.« less

Significant relaxation of residual negative carrier in polar Alq3 film directly detected by high-sensitivity photoemission

NASA Astrophysics Data System (ADS)

Kinjo, Hiroumi; Lim, Hyunsoo; Sato, Tomoya; Noguchi, Yutaka; Nakayama, Yasuo; Ishii, Hisao

2016-02-01

Tris(8-hydroxyquinoline)aluminum (Alq3) has been widely applied as a good electron-injecting layer (EIL) in organic light-emitting diodes. High-sensitivity photoemission measurement revealed a clear photoemission by visible light, although its ionization energy is 5.7 eV. This unusual photoemission is ascribed to Alq3 anions captured by positive polarization charges. The observed electron detachment energy of the anion was about 1 eV larger than the electron affinity reported by inverse photoemission. This difference suggests that the injected electron in the Alq3 layer is energetically relaxed, leading to the reduction in injection barrier. This nature is one of the reasons why Alq3 worked well as the EIL.

Preface: Special Topic on Frontiers in Molecular Scale Electronics

NASA Astrophysics Data System (ADS)

Evers, Ferdinand; Venkataraman, Latha

2017-03-01

The electronic, mechanical, and thermoelectric properties of molecular scale devices have fascinated scientists across several disciplines in natural sciences and engineering. The interest is partially technological, driven by the fast miniaturization of integrated circuits that now have reached characteristic features at the nanometer scale. Equally important, a very strong incentive also exists to elucidate the fundamental aspects of structure-function relations for nanoscale devices, which utilize molecular building blocks as functional units. Thus motivated, a rich research field has established itself, broadly termed "Molecular Electronics," that hosts a plethora of activities devoted to this goal in chemistry, physics, and electrical engineering. This Special Topic on Frontiers of Molecular Scale Electronics captures recent theoretical and experimental advances in the field.

Capturing your charity care: 5 recommendations.

PubMed

Stern, Hal T

2007-09-01

To identify all charity care patients, hospitals should: Communicate with patients at the point of service. Make qualification for charity care as simple as possible. Use electronic databases to check patient ability to pay. Use predictive modeling techniques. Identify the frequent users of the emergency department.

75 FR 26662 - Fluazinam; Pesticide Tolerances

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-12

... due to systemic toxicity and not a result of frank neurotoxicity. No signs of neurotoxicity were... chromatography with electron capture detection (GC/ECD), is available to enforce the tolerance expression for...) enforcement method is also available to enforce the tolerance expression for wine grapes, which includes...

Chasing a Fault across Ship and Shore

ERIC Educational Resources Information Center

Evans, Michael A.; Schwen, Thomas M.

2006-01-01

Knowledge management (KM) in the U.S. Navy is championed as a strategic initiative to improve shipboard maintenance and troubleshooting at a distance. The approach requires capturing, coordinating, and distributing domain expertise in electronics and computer engineering via advanced information and communication technologies. Coordination must be…

Single-electron random-number generator (RNG) for highly secure ubiquitous computing applications

NASA Astrophysics Data System (ADS)

Uchida, Ken; Tanamoto, Tetsufumi; Fujita, Shinobu

2007-11-01

Since the security of all modern cryptographic techniques relies on unpredictable and irreproducible digital keys generated by random-number generators (RNGs), the realization of high-quality RNG is essential for secure communications. In this report, a new RNG, which utilizes single-electron phenomena, is proposed. A room-temperature operating silicon single-electron transistor (SET) having nearby an electron pocket is used as a high-quality, ultra-small RNG. In the proposed RNG, stochastic single-electron capture/emission processes to/from the electron pocket are detected with high sensitivity by the SET, and result in giant random telegraphic signals (GRTS) on the SET current. It is experimentally demonstrated that the single-electron RNG generates extremely high-quality random digital sequences at room temperature, in spite of its simple configuration. Because of its small-size and low-power properties, the single-electron RNG is promising as a key nanoelectronic device for future ubiquitous computing systems with highly secure mobile communication capabilities.

Theory of Thermal Relaxation of Electrons in Semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadasivam, Sridhar; Chan, Maria K. Y.; Darancet, Pierre

2017-09-01

We compute the transient dynamics of phonons in contact with high energy ``hot'' charge carriers in 12 polar and non-polar semiconductors, using a first-principles Boltzmann transport framework. For most materials, we find that the decay in electronic temperature departs significantly from a single-exponential model at times ranging from 1 ps to 15 ps after electronic excitation, a phenomenon concomitant with the appearance of non-thermal vibrational modes. We demonstrate that these effects result from the slow thermalization within the phonon subsystem, caused by the large heterogeneity in the timescales of electron-phonon and phonon-phonon interactions in these materials. We propose a generalizedmore » 2-temperature model accounting for the phonon thermalization as a limiting step of electron-phonon thermalization, which captures the full thermal relaxation of hot electrons and holes in semiconductors. A direct consequence of our findings is that, for semiconductors, information about the spectral distribution of electron-phonon and phonon-phonon coupling can be extracted from the multi-exponential behavior of the electronic temperature.« less

Double electron capture of {sup 106}Cd in the TGV-2 experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rukhadze, N. I.; Egorov, V. G.; Kovalik, A.

2015-10-28

A new experimental run of searching for EC/EC decay of {sup 106}Cd was performed at the Modane underground laboratory (4800 m w.e.) using the TGV-2 spectrometer and ∼23.2 g {sup 106}Cd with enrichment of 99.57%. The limit on 2νEC/EC decay of {sup 106}Cd - T{sub 1/2}(2νEC/EC) > 3.1×10{sup 20} y, at 90% C.L was obtained from the preliminary calculation of experimental data accumulated for 7018 h of measurement. The limits on the resonance neutrino-less double electron capture decay of {sup 106}Cd were obtained from the measurement of ∼23.2 g of {sup 106}Cd with the low-background HPGe spectrometer OBELIX lasted 395more » h - T{sub 1/2}(KL, 2741 keV) > 0.9×10{sup 20} y and T{sub 1/2}(KK, 2718 keV) > 1.4×10{sup 20} y at 90% C.L.« less

Calculating hyperfine couplings in large ionic crystals containing hundreds of QM atoms: subsystem DFT is the key.

PubMed

Kevorkyants, Ruslan; Wang, Xiqiao; Close, David M; Pavanello, Michele

2013-11-14

We present an application of the linear scaling frozen density embedding (FDE) formulation of subsystem DFT to the calculation of isotropic hyperfine coupling constants (hfcc's) of atoms belonging to a guanine radical cation embedded in a guanine hydrochloride monohydrate crystal. The model systems range from an isolated guanine to a 15,000 atom QM/MM cluster where the QM region is comprised of 36 protonated guanine cations, 36 chlorine anions, and 42 water molecules. Our calculations show that the embedding effects of the surrounding crystal cannot be reproduced by small model systems nor by a pure QM/MM procedure. Instead, a large QM region is needed to fully capture the complicated nature of the embedding effects in this system. The unprecedented system size for a relativistic all-electron isotropic hfcc calculation can be approached in this work because the local nature of the electronic structure of the organic crystals considered is fully captured by the FDE approach.

Methyl sulfonyl polychlorinated biphenyls and 2,2-bis(4-chlorophenyl)-1,1-dichlorethene in gray seal tissues determined by gas chromatography with electron capture detection and atomic emission detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janak, K.; Becker, G.; Colmisjoe, A.

1998-06-01

The presence of 24 methyl sulfonyl polychlorinated biphenyl (PCB) congeners (MeSO{sub 2}-CBs) and 3-methyl sulfonyl 2,2-bis(4-chlorophenyl)-1,1-dichlorethene (DDE) (MeSO{sub 2}-DDE), metabolites of PCB and DDE, in blubber, lung, and liver of gray seals has been determined by using atomic emission detection (AED) and electron capture detection (ECD). Selective accumulation of aryl methyl sulfones in blubber, liver, and lung tissue was also investigated. For the liver samples, a substantial and highly specific retention of PCB methyl sulfones was observed. The atomic emission technique significantly improved the determination of measured solutes compared with ECD. Atomic emission detection was also valuable for the monitoringmore » of the prefractionation and to decrease the requirements of sample clean-up. Comparing both detection techniques showed a good correlation between the results of the AED sulfur-selective line and ECD.« less

Midwife to the greens: the electron capture detector.

PubMed

Lovelock, J E

1997-03-01

James E. Lovelock makes an account of the path he has followed since he started his scientific research at the National Institute for Medical Research (NIMR) in London in the 1940s, emphasizing the aspects related to environmental sciences. Lovelock explains the origins of the electron capture detector (ECD). So far, the ECD is the most sensitive, easily portable and inexpensive analytical apparatus capable of detecting substances present in the atmosphere at concentrations as low as parts per trillion (10(-12)). It has been the first device specifically sensitive to pollutants, and its use has provided the grounds for the development of environmental sciences, and green politics. The data gathered by the ECD about the persistence of pesticides in the environment led American biologist Rachel Carson to write her seminal book Silent Spring; data regarding the global presence of chlorofluorocarbons (CFC) in the atmosphere led Sherwood Rowland and Mario Molina to develop their theory of ozone depletion. The results of his research over the years led Lovelock himself to the development of the Gaia theory.

Towards Automated Bargaining in Electronic Markets: A Partially Two-Sided Competition Model

NASA Astrophysics Data System (ADS)

Gatti, Nicola; Lazaric, Alessandro; Restelli, Marcello

This paper focuses on the prominent issue of automating bargaining agents within electronic markets. Models of bargaining in literature deal with settings wherein there are only two agents and no model satisfactorily captures settings in which there is competition among buyers, being they more than one, and analogously among sellers. In this paper, we extend the principal bargaining protocol, i.e. the alternating-offers protocol, to capture bargaining in markets. The model we propose is such that, in presence of a unique buyer and a unique seller, agents' equilibrium strategies are those in the original protocol. Moreover, we game theoretically study the considered game providing the following results: in presence of one-sided competition (more buyers and one seller or vice versa) we provide agents' equilibrium strategies for all the values of the parameters, in presence of two-sided competition (more buyers and more sellers) we provide an algorithm that produce agents' equilibrium strategies for a large set of the parameters and we experimentally evaluate its effectiveness.

Half-life of the electron-capture decay of {sup 97}Ru: Precision measurement shows no temperature dependence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goodwin, J. R.; Golovko, V. V.; Iacob, V. E.

2009-10-15

We have measured the half-life of the electron-capture (ec) decay of {sup 97}Ru in a metallic environment, both at low temperature (19 K), and also at room temperature. We find the half-lives at both temperatures to be the same within 0.1%. This demonstrates that a recent claim that the ec decay half-life for {sup 7}Be changes by 0.9%{+-}0.2% under similar circumstances certainly cannot be generalized to other ec decays. Our results for the half-life of {sup 97}Ru, 2.8370(14) d at room temperature and 2.8382(14) d at 19 K, are consistent with, but much more precise than, previous room-temperature measurements. Inmore » addition, we have also measured the half-lives of the {beta}{sup -}-emitters {sup 103}Ru and {sup 105}Rh at both temperatures, and found them also to be unchanged.« less

Development and Early Usage Patterns of a Consumer-Facing Family Health History Tool

PubMed Central

Hulse, Nathan C.; Ranade-Kharkar, Pallavi; Post, Herman; Wood, Grant M.; Williams, Marc S.; Haug, Peter J.

2011-01-01

Personalized medicine will require detailed clinical patient profiles, and a particular focus on capturing data that is useful in forecasting risk. A detailed family health history is considered a critical component of these profiles, insomuch that it has been coined as ‘the best genetic test available’. Despite this, tools aimed at capturing this information for use in electronic health records have been characterized as inadequate. In this manuscript we detail the creation of a patient-facing family health history tool known as OurFamilyHealth, whose long-term emphasis is to facilitate risk assessment and clinical decision support. We present the rationale for such a tool, describe its development and release as a component of Intermountain Healthcare’s patient portal, and detail early usage statistics surrounding the application. Data derived from the tool since its release are also compared against family history charting patterns in Intermountain’s electronic health records, revealing differences in data availability. PMID:22195113

Influence of nuclear exchange on nonadiabatic electron processes in H(+)+H2 collisions.

PubMed

Errea, L F; Illescas, Clara; Macías, A; Méndez, L; Pons, B; Rabadán, I; Riera, A

2010-12-28

H(+)+H(2) collisions are studied by means of a semiclassical approach that explicitly accounts for nuclear rearrangement channels in nonadiabatic electron processes. A set of classical trajectories is used to describe the nuclear motion, while the electronic degrees of freedom are treated quantum mechanically in terms of a three-state expansion of the collision wavefunction. We describe electron capture and vibrational excitation, which can also involve nuclear exchange and dissociation, in the E = 2-1000 eV impact energy range. We compare dynamical results obtained with two parametrizations of the potential energy surface of H(3)(+) ground electronic state. Total cross sections for E > 10 eV agree with previous results using a vibronic close-coupling expansion, and with experimental data for E < 10 eV. Additionally, some prototypical features of both nuclear and electron dynamics at low E are discussed.

Multistage Coupling of Laser-Wakefield Accelerators with Curved Plasma Channels.

PubMed

Luo, J; Chen, M; Wu, W Y; Weng, S M; Sheng, Z M; Schroeder, C B; Jaroszynski, D A; Esarey, E; Leemans, W P; Mori, W B; Zhang, J

2018-04-13

Multistage coupling of laser-wakefield accelerators is essential to overcome laser energy depletion for high-energy applications such as TeV-level electron-positron colliders. Current staging schemes feed subsequent laser pulses into stages using plasma mirrors while controlling electron beam focusing with plasma lenses. Here a more compact and efficient scheme is proposed to realize the simultaneous coupling of the electron beam and the laser pulse into a second stage. A partly curved channel, integrating a straight acceleration stage with a curved transition segment, is used to guide a fresh laser pulse into a subsequent straight channel, while the electrons continue straight. This scheme benefits from a shorter coupling distance and continuous guiding of the electrons in plasma while suppressing transverse beam dispersion. Particle-in-cell simulations demonstrate that the electron beam from a previous stage can be efficiently injected into a subsequent stage for further acceleration while maintaining high capture efficiency, stability, and beam quality.

Critical Role of the Exchange Interaction for the Electronic Structure and Charge-Density-Wave Formation in TiSe2

NASA Astrophysics Data System (ADS)

Hellgren, Maria; Baima, Jacopo; Bianco, Raffaello; Calandra, Matteo; Mauri, Francesco; Wirtz, Ludger

2017-10-01

We show that the inclusion of screened exchange via hybrid functionals provides a unified description of the electronic and vibrational properties of TiSe2 . In contrast to local approximations in density functional theory, the explicit inclusion of exact, nonlocal exchange captures the effects of the electron-electron interaction needed to both separate the Ti -d states from the Se -p states and stabilize the charge-density-wave (CDW) (or low-T ) phase through the formation of a p -d hybridized state. We further show that this leads to an enhanced electron-phonon coupling that can drive the transition even if a small gap opens in the high-T phase. Finally, we demonstrate that the hybrid functionals can generate a CDW phase where the electronic bands, the geometry, and the phonon frequencies are in agreement with experiments.

Multistage Coupling of Laser-Wakefield Accelerators with Curved Plasma Channels

NASA Astrophysics Data System (ADS)

Luo, J.; Chen, M.; Wu, W. Y.; Weng, S. M.; Sheng, Z. M.; Schroeder, C. B.; Jaroszynski, D. A.; Esarey, E.; Leemans, W. P.; Mori, W. B.; Zhang, J.

2018-04-01

Multistage coupling of laser-wakefield accelerators is essential to overcome laser energy depletion for high-energy applications such as TeV-level electron-positron colliders. Current staging schemes feed subsequent laser pulses into stages using plasma mirrors while controlling electron beam focusing with plasma lenses. Here a more compact and efficient scheme is proposed to realize the simultaneous coupling of the electron beam and the laser pulse into a second stage. A partly curved channel, integrating a straight acceleration stage with a curved transition segment, is used to guide a fresh laser pulse into a subsequent straight channel, while the electrons continue straight. This scheme benefits from a shorter coupling distance and continuous guiding of the electrons in plasma while suppressing transverse beam dispersion. Particle-in-cell simulations demonstrate that the electron beam from a previous stage can be efficiently injected into a subsequent stage for further acceleration while maintaining high capture efficiency, stability, and beam quality.

Field emission chemical sensor for receptor/binder, such as antigen/antibody

DOEpatents

Panitz, John A.

1986-01-01

A field emission chemical sensor for specific detection of a chemical entity in a sample includes a closed chamber enclosing two field emission electrode sets, each field emission electrode set comprising (a) an electron emitter electrode from which field emission electrons can be emitted when an effective voltage is connected to the electrode set; and (b) a collector electrode which will capture said electrons emitted from said emitter electrode. One of the electrode sets is passive to the chemical entity and the other is active thereto and has an active emitter electrode which will bind the chemical entity when contacted therewith.

A flexible, on-line magnetic spectrometer for ultra-intense laser produced fast electron measurement

NASA Astrophysics Data System (ADS)

Ge, Xulei; Yuan, Xiaohui; Yang, Su; Deng, Yanqing; Wei, Wenqing; Fang, Yuan; Gao, Jian; Liu, Feng; Chen, Min; Zhao, Li; Ma, Yanyun; Sheng, Zhengming; Zhang, Jie

2018-04-01

We have developed an on-line magnetic spectrometer to measure energy distributions of fast electrons generated from ultra-intense laser-solid interactions. The spectrometer consists of a sheet of plastic scintillator, a bundle of non-scintillating plastic fibers, and an sCMOS camera recording system. The design advantages include on-line capturing ability, versatility of detection arrangement, and resistance to harsh in-chamber environment. The validity of the instrument was tested experimentally. This spectrometer can be applied to the characterization of fast electron source for understanding fundamental laser-plasma interaction physics and to the optimization of high-repetition-rate laser-driven applications.

Scanning-tunneling microscope imaging of single-electron solitons in a material with incommensurate charge-density waves.

PubMed

Brazovskii, Serguei; Brun, Christophe; Wang, Zhao-Zhong; Monceau, Pierre

2012-03-02

We report on scanning-tunneling microscopy experiments in a charge-density wave (CDW) system allowing visually capturing and studying in detail the individual solitons corresponding to the self-trapping of just one electron. This "Amplitude Soliton" is marked by vanishing of the CDW amplitude and by the π shift of its phase. It might be the realization of the spinon--the long-sought particle (along with the holon) in the study of science of strongly correlated electronic systems. As a distinct feature we also observe one-dimensional Friedel oscillations superimposed on the CDW which develop independently of solitons.

Physics design of the in-vessel collection optics for the ITER electron cyclotron emission diagnostic.

PubMed

Rowan, W L; Houshmandyar, S; Phillips, P E; Austin, M E; Beno, J H; Hubbard, A E; Khodak, A; Ouroua, A; Taylor, G

2016-11-01

Measurement of the electron cyclotron emission (ECE) is one of the primary diagnostics for electron temperature in ITER. In-vessel, in-vacuum, and quasi-optical antennas capture sufficient ECE to achieve large signal to noise with microsecond temporal resolution and high spatial resolution while maintaining polarization fidelity. Two similar systems are required. One views the plasma radially. The other is an oblique view. Both views can be used to measure the electron temperature, while the oblique is also sensitive to non-thermal distortion in the bulk electron distribution. The in-vacuum optics for both systems are subject to degradation as they have a direct view of the ITER plasma and will not be accessible for cleaning or replacement for extended periods. Blackbody radiation sources are provided for in situ calibration.

Suppression of electron leakage in 808 nm laser diodes with asymmetric waveguide layer

NASA Astrophysics Data System (ADS)

Xiang, Li; Degang, Zhao; Desheng, Jiang; Ping, Chen; Zongshun, Liu; Jianjun, Zhu; Ming, Shi; Danmei, Zhao; Wei, Liu

2016-01-01

Electron leakage in GaAs-based separately confined heterostructure 808 nm laser diodes (SCH LDs) has a serious influence on device performance. Here, in order to reduce the energy of electrons injected into the quantum well (QW), an AlGaAs interlayer with a smaller Al component is added between the active region and the n-side waveguide. Numerical device simulation reveals that when the Al-composition of the AlGaAs interlayer and its thickness are properly elected, the electron leakage is remarkably depressed and the characteristics of LDs are improved, owing to the reduction of injected electron energy and the improvement of QW capture efficiency. Project supported by the National Natural Science Foundation of China (Nos. 61377020, 61376089, 61223005, 61176126) and the National Science Fund for Distinguished Young Scholars (No. 60925017).

Physics design of the in-vessel collection optics for the ITER electron cyclotron emission diagnostic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rowan, W. L., E-mail: w.l.rowan@austin.utexas.edu; Houshmandyar, S.; Phillips, P. E.

2016-11-15

Measurement of the electron cyclotron emission (ECE) is one of the primary diagnostics for electron temperature in ITER. In-vessel, in-vacuum, and quasi-optical antennas capture sufficient ECE to achieve large signal to noise with microsecond temporal resolution and high spatial resolution while maintaining polarization fidelity. Two similar systems are required. One views the plasma radially. The other is an oblique view. Both views can be used to measure the electron temperature, while the oblique is also sensitive to non-thermal distortion in the bulk electron distribution. The in-vacuum optics for both systems are subject to degradation as they have a direct viewmore » of the ITER plasma and will not be accessible for cleaning or replacement for extended periods. Blackbody radiation sources are provided for in situ calibration.« less

Physics design of the in-vessel collection optics for the ITER electron cyclotron emission diagnostic

DOE PAGES

Rowan, W. L.; Houshmandyar, S.; Phillips, P. E.; ...

2016-09-07

Measurement of the electron cyclotron emission (ECE) is one of the primary diagnostics for electron temperature in ITER. In-vessel, in-vacuum, and quasi-optical antennas capture sufficient ECE to achieve large signal to noise with microsecond temporal resolution and high spatial resolution while maintaining polarization fidelity. Two similar systems are required. One views the plasma radially. The other is an oblique view. Both views can be used to measure the electron temperature, while the oblique is also sensitive to non-thermal distortion in the bulk electron distribution. The in-vacuum optics for both systems are subject to degradation as they have a direct viewmore » of the ITER plasma and will not be accessible for cleaning or replacement for extended periods. Here, blackbody radiation sources are provided for in situ calibration.« less

A quartz nanopillar hemocytometer for high-yield separation and counting of CD4+ T lymphocytes

NASA Astrophysics Data System (ADS)

Kim, Dong-Joo; Seol, Jin-Kyeong; Wu, Yu; Ji, Seungmuk; Kim, Gil-Sung; Hyung, Jung-Hwan; Lee, Seung-Yong; Lim, Hyuneui; Fan, Rong; Lee, Sang-Kwon

2012-03-01

We report the development of a novel quartz nanopillar (QNP) array cell separation system capable of selectively capturing and isolating a single cell population including primary CD4+ T lymphocytes from the whole pool of splenocytes. Integrated with a photolithographically patterned hemocytometer structure, the streptavidin (STR)-functionalized-QNP (STR-QNP) arrays allow for direct quantitation of captured cells using high content imaging. This technology exhibits an excellent separation yield (efficiency) of ~95.3 +/- 1.1% for the CD4+ T lymphocytes from the mouse splenocyte suspensions and good linear response for quantitating captured CD4+ T-lymphoblasts, which is comparable to flow cytometry and outperforms any non-nanostructured surface capture techniques, i.e. cell panning. This nanopillar hemocytometer represents a simple, yet efficient cell capture and counting technology and may find immediate applications for diagnosis and immune monitoring in the point-of-care setting.We report the development of a novel quartz nanopillar (QNP) array cell separation system capable of selectively capturing and isolating a single cell population including primary CD4+ T lymphocytes from the whole pool of splenocytes. Integrated with a photolithographically patterned hemocytometer structure, the streptavidin (STR)-functionalized-QNP (STR-QNP) arrays allow for direct quantitation of captured cells using high content imaging. This technology exhibits an excellent separation yield (efficiency) of ~95.3 +/- 1.1% for the CD4+ T lymphocytes from the mouse splenocyte suspensions and good linear response for quantitating captured CD4+ T-lymphoblasts, which is comparable to flow cytometry and outperforms any non-nanostructured surface capture techniques, i.e. cell panning. This nanopillar hemocytometer represents a simple, yet efficient cell capture and counting technology and may find immediate applications for diagnosis and immune monitoring in the point-of-care setting. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11338d

A high-current electron gun for the electron beam ion trap at the National Superconducting Cyclotron Laboratory.

PubMed

Schwarz, S; Baumann, T M; Kittimanapun, K; Lapierre, A; Snyder, A

2014-02-01

The Electron Beam Ion Trap (EBIT) in NSCL's reaccelerator ReA uses continuous ion injection and accumulation. In order to maximize capture efficiency and minimize breeding time into high charge states, the EBIT requires a high-current/high current-density electron beam. A new electron gun insert based on a concave Ba-dispenser cathode has been designed and built to increase the current transmitted through the EBIT's superconducting magnet. With the new insert, stable EBIT operating conditions with 0.8 A of electron beam have been established. The design of the electron gun is presented together with calculated and measured perveance data. In order to assess the experimental compression of the electron beam, a pinhole CCD camera has been set up to measure the electron beam radius. The camera observes X-rays emitted from highly charged ions, excited by the electron beam. Initial tests with this camera setup will be presented. They indicate that a current density of 640 A/cm(2) has been reached when the EBIT magnet was operated at 4 T.

A high-current electron gun for the electron beam ion trap at the National Superconducting Cyclotron Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwarz, S., E-mail: schwarz@nscl.msu.edu; Baumann, T. M.; Kittimanapun, K.

The Electron Beam Ion Trap (EBIT) in NSCL’s reaccelerator ReA uses continuous ion injection and accumulation. In order to maximize capture efficiency and minimize breeding time into high charge states, the EBIT requires a high-current/high current-density electron beam. A new electron gun insert based on a concave Ba-dispenser cathode has been designed and built to increase the current transmitted through the EBIT’s superconducting magnet. With the new insert, stable EBIT operating conditions with 0.8 A of electron beam have been established. The design of the electron gun is presented together with calculated and measured perveance data. In order to assessmore » the experimental compression of the electron beam, a pinhole CCD camera has been set up to measure the electron beam radius. The camera observes X-rays emitted from highly charged ions, excited by the electron beam. Initial tests with this camera setup will be presented. They indicate that a current density of 640 A/cm{sup 2} has been reached when the EBIT magnet was operated at 4 T.« less

Negative ion spectrometry for detecting nitrated explosives

NASA Technical Reports Server (NTRS)

Boettger, H. G.; Yinon, J.

1975-01-01

Ionization procedure is modified to produce mainly negative ions by electron capture. Peaks of negative ions are monitored conventionally. Nitrated organic materials could be identified directly from sample sniff inlet stream by suitably modified mass spectrometer because of unique electronegativity which nitro group imparts to organic material.

Computational Aerodynamic Analysis of the Flow Field about a Hypervelocity Test Sled

DTIC Science & Technology

2002-03-01

scheme would capture the steady solution without the convergence difficulties. 6-3 Bibliography 1. Amtec Engineering Incorporated, Bellevue WA. CFD...Analyzer User’s Manual, Version 2.0 , 1999. Electronic documentation, http://www.amtec.com. 2. Amtec Engineering Incorporated, Bellevue WA. Tecplot User’s

Stabilized pigment and method for producing the same

NASA Technical Reports Server (NTRS)

Morrison, Stanley Roy (Inventor); Freund, Thomas (Inventor)

1976-01-01

A chemical species, present in two oxidation states which differ from one another by one equivalent, is added to pigment materials to serve as a recombination center for alternately capturing electrons and holes produced by the pigment materials when they are subjected to ultraviolet light exposure.

FAC: Flexible Atomic Code

NASA Astrophysics Data System (ADS)

Gu, Ming Feng

2018-02-01

FAC calculates various atomic radiative and collisional processes, including radiative transition rates, collisional excitation and ionization by electron impact, energy levels, photoionization, and autoionization, and their inverse processes radiative recombination and dielectronic capture. The package also includes a collisional radiative model to construct synthetic spectra for plasmas under different physical conditions.