Determination of trap distributions from current characteristics of pentacene field-effect transistors with surface modified gate oxide

NASA Astrophysics Data System (ADS)

Scheinert, Susanne; Pernstich, Kurt P.; Batlogg, Bertram; Paasch, Gernot

2007-11-01

It has been demonstrated [K. P. Pernstich, S. Haas, D. Oberhoff, C. Goldmann, D. J. Gundlach, B. Batlogg, A. N. Rashid, and G. Schitter, J. Appl. Phys. 96, 6431 (2004)] that a controllable shift of the threshold voltage in pentacene thin film transistors is caused by the use of organosilanes with different functional groups forming a self-assembled monolayer (SAM) on the gate oxide. The observed broadening of the subthreshold region indicates that the SAM creates additional trap states. Indeed, it is well known that traps strongly influence the behavior of organic field-effect transistors (OFETs). Therefore, the so-called "amorphous silicon (a-Si) model" has been suggested to be an appropriate model to describe OFETs. The main specifics of this model are transport of carriers above a mobility edge obeying Boltzmann statistics and exponentially distributed tail states and deep trap states. Here, approximate trap distributions are determined by adjusting two-dimensional numerical simulations to the experimental data. It follows from a systematic variation of parameters describing the trap distributions that the existence of both donorlike and acceptorlike trap distributions near the valence band, respectively, and a fixed negative interface charge have to be assumed. For two typical devices with different organosilanes the electrical characteristics can be described well with a donorlike bulk trap distribution, an acceptorlike interface distribution, and/or a fixed negative interface charge. As expected, the density of the fixed or trapped interface charge depends strongly on the surface treatment of the dielectric. There are some limitations in determining the trap distributions caused by either slow time-dependent processes resulting in differences between transfer and output characteristics, or in the uncertainty of the effective mobility.

48 CFR 2152.216-70 - Fixed price with limited cost redetermination-risk charge.

Code of Federal Regulations, 2010 CFR

2010-10-01

... cost redetermination-risk charge. 2152.216-70 Section 2152.216-70 Federal Acquisition Regulations....216-70 Fixed price with limited cost redetermination—risk charge. As prescribed in 2116.270-1(a), insert the following clause when a risk charge is negotiated: Fixed Price With Limited Cost...

Injectable hydrogels with high fixed charge density and swelling pressure for nucleus pulposus repair: biomimetic glycosaminoglycan analogues.

PubMed

Sivan, S S; Roberts, S; Urban, J P G; Menage, J; Bramhill, J; Campbell, D; Franklin, V J; Lydon, F; Merkher, Y; Maroudas, A; Tighe, B J

2014-03-01

The load-bearing biomechanical role of the intervertebral disc is governed by the composition and organization of its major macromolecular components, collagen and aggrecan. The major function of aggrecan is to maintain tissue hydration, and hence disc height, under the high loads imposed by muscle activity and body weight. Key to this role is the high negative fixed charge of its glycosaminoglycan side chains, which impart a high osmotic pressure to the tissue, thus regulating and maintaining tissue hydration and hence disc height under load. In degenerate discs, aggrecan degrades and is lost from the disc, particularly centrally from the nucleus pulposus. This loss of fixed charge results in reduced hydration and loss of disc height; such changes are closely associated with low back pain. The present authors developed biomimetic glycosaminoglycan analogues based on sulphonate-containing polymers. These biomimetics are deliverable via injection into the disc where they polymerize in situ, forming a non-degradable, nuclear "implant" aimed at restoring disc height to degenerate discs, thereby relieving back pain. In vitro, these glycosaminoglycan analogues possess appropriate fixed charge density, hydration and osmotic responsiveness, thereby displaying the capacity to restore disc height and function. Preliminary biomechanical tests using a degenerate explant model showed that the implant adapts to the space into which it is injected and restores stiffness. These hydrogels mimic the role taken by glycosaminoglycans in vivo and, unlike other hydrogels, provide an intrinsic swelling pressure, which can maintain disc hydration and height under the high and variable compressive loads encountered in vivo. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Modulating the fixed charge density in silicon nitride films while monitoring the surface recombination velocity by photoluminescence imaging

NASA Astrophysics Data System (ADS)

Bazilchuk, Molly; Haug, Halvard; Marstein, Erik Stensrud

2015-04-01

Several important semiconductor devices such as solar cells and photodetectors may be fabricated based on surface inversion layer junctions induced by fixed charge in a dielectric layer. Inversion layer junctions can easily be fabricated by depositing layers with a high density of fixed charge on a semiconducting substrate. Increasing the fixed charge improves such devices; for instance, the efficiency of a solar cell can be substantially increased by reducing the surface recombination velocity, which is a function of the fixed charge density. Methods for increasing the charge density are therefore of interest. In this work, the fixed charge density in silicon nitride layers deposited by plasma enhanced chemical vapor deposition is increased to very high values above 1 × 1013 cm-2 after the application of an external voltage to a gate electrode. The effect of the fixed charge density on the surface recombination velocity was experimentally observed using the combination of capacitance-voltage characterization and photoluminescence imaging, showing a significant reduction in the surface recombination velocity for increasing charge density. The surface recombination velocity vs. charge density data was analyzed using a numerical device model, which indicated the presence of a sub-surface damage region formed during deposition of the layers. Finally, we have demonstrated that the aluminum electrodes used for charge injection may be chemically removed in phosphoric acid without loss of the underlying charge. The injected charge was shown to be stable for a prolonged time period, leading us to propose charge injection in silicon nitride films by application of soaking voltage as a viable method for fabricating inversion layer devices.

Optical patterning of trapped charge in nitrogen-doped diamond

NASA Astrophysics Data System (ADS)

Jayakumar, Harishankar; Henshaw, Jacob; Dhomkar, Siddharth; Pagliero, Daniela; Laraoui, Abdelghani; Manson, Neil B.; Albu, Remus; Doherty, Marcus W.; Meriles, Carlos A.

2016-08-01

The nitrogen-vacancy (NV) centre in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge, which can be attained by optical excitation. Here, we use two-colour optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs, and to subsequently probe the corresponding redistribution of charge. We uncover the formation of spatial patterns of trapped charge, which we qualitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects. Further, by using the NV as a probe, we map the relative fraction of positively charged nitrogen on localized optical excitation. These observations may prove important to transporting quantum information between NVs or to developing three-dimensional, charge-based memories.

Optical patterning of trapped charge in nitrogen-doped diamond.

PubMed

Jayakumar, Harishankar; Henshaw, Jacob; Dhomkar, Siddharth; Pagliero, Daniela; Laraoui, Abdelghani; Manson, Neil B; Albu, Remus; Doherty, Marcus W; Meriles, Carlos A

2016-08-30

The nitrogen-vacancy (NV) centre in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge, which can be attained by optical excitation. Here, we use two-colour optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs, and to subsequently probe the corresponding redistribution of charge. We uncover the formation of spatial patterns of trapped charge, which we qualitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects. Further, by using the NV as a probe, we map the relative fraction of positively charged nitrogen on localized optical excitation. These observations may prove important to transporting quantum information between NVs or to developing three-dimensional, charge-based memories.

Optical patterning of trapped charge in nitrogen-doped diamond

PubMed Central

Jayakumar, Harishankar; Henshaw, Jacob; Dhomkar, Siddharth; Pagliero, Daniela; Laraoui, Abdelghani; Manson, Neil B.; Albu, Remus; Doherty, Marcus W.; Meriles, Carlos A.

2016-01-01

The nitrogen-vacancy (NV) centre in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge, which can be attained by optical excitation. Here, we use two-colour optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs, and to subsequently probe the corresponding redistribution of charge. We uncover the formation of spatial patterns of trapped charge, which we qualitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects. Further, by using the NV as a probe, we map the relative fraction of positively charged nitrogen on localized optical excitation. These observations may prove important to transporting quantum information between NVs or to developing three-dimensional, charge-based memories. PMID:27573190

Influence of humic acid concentration on nTiO2 attachment to quartz sand and Fe-coated quartz sand

NASA Astrophysics Data System (ADS)

Cheng, T.; Wu, Y.

2016-12-01

The transport of nano-scale or micro-scale titanium dioxide particles (nTiO2) in subsurface environments are strongly influenced by nTiO2 attachment to sediment grains. The objective of this study is to investigate the role of humic acid (HA) in the attachment of nTiO2 to sand at low HA concentrations that are relevant to typical groundwater conditions, so that mechanisms that control nTiO2 immobilization and transport in groundwater can be elucidated. nTiO2 may carry either positive or negative charges in natural water, therefore, environmental factors such as pH, humic substances, and Fe oxyhydroxide coatings on sediment grains, which are known to control the transport of negatively-charged colloids, may influence nTiO2 in different manners. Attachment of nTiO2 to quartz sand and Fe oxyhydroxide coated quartz sand are experimentally measured under a range of HA concentrations at fixed pH. Experimental results show that at pH 5, negatively-charged HA strongly adsorbs to positively-charged nTiO2 and Fe oxyhydroxide, which, at low HA concentrations, partially neutralizes the positive charges on nTiO2 and Fe oxyhydroxide, and therefore decreases the repulsive electrostatic forces between the surfaces, resulting in relatively high nTiO2 attachment. At high HA concentrations, adsorbed HA reverses the surface charges of nTiO2 and Fe oxyhydroxide, and makes nTiO2 and Fe oxyhydroxide strongly negatively charged, resulting in low nTiO2 attachment. At pH 9, HA, nTiO2, and Fe oxyhydroxide are all negatively charged, and HA adsorption is low and does not have a strong impact on the attachment of nTiO2. This study demonstrates that the changes in surface charges of nTiO2 and Fe oxyhydroxide coating caused by HA adsorption could be a key factor that controls the attachment of nTiO2 to sediment grains.

Charged particle multiplicities in deep inelastic scattering at HERA

NASA Astrophysics Data System (ADS)

Aid, S.; Anderson, M.; Andreev, V.; Andrieu, B.; Appuhn, R.-D.; Babaev, A.; Bähr, J.; Bán, J.; Ban, Y.; Baranov, P.; Barrelet, E.; Barschke, R.; Bartel, W.; Barth, M.; Bassler, U.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bernardi, G.; Bertrand-Coremans, G.; Besançon, M.; Beyer, R.; Biddulph, P.; Bispham, P.; Bizot, J. C.; Blobel, V.; Borras, K.; Botterweck, F.; Boudry, V.; Braemer, A.; Braunschweig, W.; Brisson, V.; Bruel, P.; Bruncko, D.; Brune, C.; Buchholz, R.; Büngener, L.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Burton, M. J.; Calvet, D.; Campbell, A. J.; Carli, T.; Charlet, M.; Clarke, D.; Clegg, A. B.; Clerbaux, B.; Cocks, S.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Courau, A.; Cousinou, M.-C.; Cozzika, G.; Criegee, L.; Cussans, D. G.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Dau, W. D.; Daum, K.; David, M.; Davis, C. L.; Delcourt, B.; de Roeck, A.; de Wolf, E. A.; Dirkmann, M.; Dixon, P.; di Nezza, P.; Dlugosz, W.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Droutskoi, A.; Dünger, O.; Duhm, H.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Elsen, E.; Erdmann, M.; Erdmann, W.; Evrard, E.; Fahr, A. B.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Formánek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Gabathuler, E.; Gabathuler, K.; Gaede, F.; Garvey, J.; Gayler, J.; Gebauer, M.; Genzel, H.; Gerhards, R.; Glazov, A.; Goerlach, U.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goldner, D.; Golec-Biernat, K.; Gonzalez-Pineiro, B.; Gorelov, I.; Grab, C.; Grässler, H.; Greenshaw, T.; Griffiths, R. K.; Grindhammer, G.; Gruber, A.; Gruber, C.; Haack, J.; Hadig, T.; Haidt, D.; Hajduk, L.; Hampel, M.; Haynes, W. J.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herynek, I.; Hess, M. F.; Hewitt, K.; Hildesheim, W.; Hiller, K. H.; Hilton, C. D.; Hladký, J.; Hoeger, K. C.; Höppner, M.; Hoffmann, D.; Holtom, T.; Horisberger, R.; Hudgson, V. L.; Hütte, M.; Ibbotson, M.; Itterbeck, H.; Jacholkowska, A.; Jacobsson, C.; Jaffre, M.; Janoth, J.; Jansen, T.; Jönsson, L.; Johnson, D. P.; Jung, H.; Kalmus, P. I. P.; Kander, M.; Kant, D.; Kaschowitz, R.; Kathage, U.; Katzy, J.; Kaufmann, H. H.; Kaufmann, O.; Kazarian, S.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Köhler, T.; Köhne, J. H.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krämerkämper, T.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Küster, H.; Kuhlen, M.; Kurča, T.; Kurzhöfer, J.; Lacour, D.; Laforge, B.; Lander, R.; Landon, M. P. J.; Lange, W.; Langenegger, U.; Laporte, J.-F.; Lebedev, A.; Lehner, F.; Levonian, S.; Lindström, G.; Lindstroem, M.; Link, J.; Linsel, F.; Lipinski, J.; List, B.; Lobo, G.; Lomas, J. W.; Lopez, G. C.; Lubimov, V.; Lüke, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Maraček, R.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, G.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Mavroidis, T.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Meyer, A.; Meyer, A.; Meyer, H.; Meyer, J.; Meyer, P.-O.; Migliori, A.; Mikocki, S.; Milstead, D.; Moeck, J.; Moreau, F.; Morris, J. V.; Mroczko, E.; Müller, D.; Müller, G.; Müller, K.; Müller, M.; Murín, P.; Nagovizin, V.; Nahnhauer, R.; Naroska, B.; Naumann, Th.; Négri, I.; Newman, P. R.; Newton, D.; Nguyen, H. K.; Nicholls, T. C.; Niebergall, F.; Niebuhr, C.; Niedzballa, Ch.; Niggli, H.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg-Werther, M.; Oakden, M.; Oberlack, H.; Olsson, J. E.; Ozerov, D.; Palmen, P.; Panaro, E.; Panitch, A.; Pascaud, C.; Patel, G. D.; Pawletta, H.; Peppel, E.; Perez, E.; Phillips, J. P.; Pieuchot, A.; Pitzl, D.; Pope, G.; Prell, S.; Rabbertz, K.; Rädel, G.; Reimer, P.; Reinshagen, S.; Rick, H.; Riech, V.; Riedlberger, J.; Riepenhausen, F.; Riess, S.; Rizvi, E.; Robertson, S. M.; Robmann, P.; Roloff, H. E.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Rouse, F.; Royon, C.; Rüter, K.; Rusakov, S.; Rybicki, K.; Sankey, D. P. C.; Schacht, P.; Schiek, S.; Schleif, S.; Schleper, P.; von Schlippe, W.; Schmidt, D.; Schmidt, G.; Schöning, A.; Schröder, V.; Schuhmann, E.; Schwab, B.; Sefkow, F.; Seidel, M.; Sell, R.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Smirnov, P.; Smith, J. R.; Solochenko, V.; Soloviev, Y.; Specka, A.; Spiekermann, J.; Spielman, S.; Spitzer, H.; Squinabol, F.; Steenbock, M.; Steffen, P.; Steinberg, R.; Steiner, H.; Steinhart, J.; Stella, B.; Stellberger, A.; Stier, J.; Stiewe, J.; Stößlein, U.; Stolze, K.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Tapprogge, S.; Taševský, M.; Tchernyshov, V.; Tchetchelnitski, S.; Theissen, J.; Thiebaux, C.; Thompson, G.; Truöl, P.; Tsipolitis, G.; Turnau, J.; Tutas, J.; Uelkes, P.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; Vandenplas, D.; van Esch, P.; van Mechelen, P.; Vazdik, Y.; Verrecchia, P.; Villet, G.; Wacker, K.; Wagener, A.; Wagener, M.; Walther, A.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wengler, T.; Werner, M.; West, L. R.; Wilksen, T.; Willard, S.; Winde, M.; Winter, G.-G.; Wittek, C.; Wobisch, M.; Wünsch, E.; Žáček, J.; Zarbock, D.; Zhang, Z.; Zhokin, A.; Zini, P.; Zomer, F.; Zsembery, J.; Zuber, K.; Zurnedden, M.

1996-12-01

Using the H1 detector at HERA, charged particle multiplicity distributions in deep inelastic e + p scattering have been measured over a large kinematical region. The evolution with W and Q 2 of the multiplicity distribution and of the multiplicity moments in pseudorapidity domains of varying size is studied in the current fragmentation region of the hadronic centre-of-mass frame. The results are compared with data from fixed target lepton-nucleon interactions, e + e - annihilations and hadron-hadron collisions as well as with expectations from QCD based parton models. Fits to the Negative Binomial and Lognormal distributions are presented.

Fixed charge in the cell membrane

PubMed Central

Elul, R.

1967-01-01

1. Focal electric field was generated by passing a current of 5 × 10-7 to 1 × 10-5 A from a micropipette into the culture medium. Movement of cells at a distance of 5-50 μ from the electrode tip was observed. In case of cells embedded in the culture only local deformation of the membrane was observed. 2. The cell species explored included neurones, glia, muscle fibres, connective cells, malignant cells and erythrocytes. All cells responded in a similar manner to the electric field, and the current required was in the same range. 3. Cells were attracted to a positive micropipette and repelled from a negative one: the only exception was observed in certain malignant cells which moved in the opposite direction. 4. Movement and membrane deformation could be obtained with electrodes filled with various concentrated and isotonic solutions. The composition of the culture medium also had no qualitative influence on these effects. 5. Metabolic poisons or rupture of the cell membrane had no effect on the movement. Isolated membrane fragments showed movement similar to that of intact cells. 6. The possibility of artifacts due to proximity of the focal electrode is considered. It is shown that electro-osmosis cannot account for the present observations. Some other artifacts are also excluded. 7. It is proposed that the most satisfactory way to account for the present observations is by a membrane carrying negative fixed charge of the order of 2·5 × 103 e.s.u./cm2. Some physiological consequences of presence of negative charge in the membrane are briefly discussed. ImagesFig. 1Fig. 2Fig. 3 PMID:6040152

A managerial approach to allocating indirect fixed costs in health care organizations.

PubMed

Goldschmidt, Y; Gafni, A

1990-01-01

To allocate indirect fixed costs to the different units in an organization, fixed costs of a supporting service should be charged to the factor that creates the demand for the service (using the dual-rate-charging method) and overhead costs should be charged to the binding constraint of the organization.

Charged fixed point in the Ginzburg-Landau superconductor and the role of the Ginzburg parameter /κ

NASA Astrophysics Data System (ADS)

Kleinert, Hagen; Nogueira, Flavio S.

2003-02-01

We present a semi-perturbative approach which yields an infrared-stable fixed point in the Ginzburg-Landau for N=2, where N/2 is the number of complex components. The calculations are done in d=3 dimensions and below Tc, where the renormalization group functions can be expressed directly as functions of the Ginzburg parameter κ which is the ratio between the two fundamental scales of the problem, the penetration depth λ and the correlation length ξ. We find a charged fixed point for κ>1/ 2, that is, in the type II regime, where Δκ≡κ-1/ 2 is shown to be a natural expansion parameter. This parameter controls a momentum space instability in the two-point correlation function of the order field. This instability appears at a non-zero wave-vector p0 whose magnitude scales like ˜ Δκ β¯, with a critical exponent β¯=1/2 in the one-loop approximation, a behavior known from magnetic systems with a Lifshitz point in the phase diagram. This momentum space instability is argued to be the origin of the negative η-exponent of the order field.

Optical patterning of trapped charge in nitrogen-doped diamond

NASA Astrophysics Data System (ADS)

Dhomkar, Siddharth; Jayakumar, Harishankar; Pagliero, Daniela; Laraoui, Abdelghani; Albu, Remus; Manson, Neil; Doherty, Marcus; Henshaw, Jacob; Meriles, Carlos

The nitrogen-vacancy (NV) center in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge state, which can be attained by optical illumination. Here we use two-color optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion, and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs and to subsequently probe the corresponding redistribution of charge. We uncover the formation of various spatial patterns of trapped charge, which we semi-quantitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects in the diamond lattice. Further, by using the NV as a local probe, we map the relative fraction of positively charged nitrogen upon localized optical excitation. These observations may prove important to various technologies, including the transport of quantum information between remote NVs and the development of three-dimensional, charge-based memories. We acknowledge support from the National Science Foundation through Grant NSF-1314205.

Dynamic structure mediates halophilic adaptation of a DNA polymerase from the deep-sea brines of the Red Sea.

PubMed

Takahashi, Masateru; Takahashi, Etsuko; Joudeh, Luay I; Marini, Monica; Das, Gobind; Elshenawy, Mohamed M; Akal, Anastassja; Sakashita, Kosuke; Alam, Intikhab; Tehseen, Muhammad; Sobhy, Mohamed A; Stingl, Ulrich; Merzaban, Jasmeen S; Di Fabrizio, Enzo; Hamdan, Samir M

2018-01-24

The deep-sea brines of the Red Sea are remote and unexplored environments characterized by high temperatures, anoxic water, and elevated concentrations of salt and heavy metals. This environment provides a rare system to study the interplay between halophilic and thermophilic adaptation in biologic macromolecules. The present article reports the first DNA polymerase with halophilic and thermophilic features. Biochemical and structural analysis by Raman and circular dichroism spectroscopy showed that the charge distribution on the protein's surface mediates the structural balance between stability for thermal adaptation and flexibility for counteracting the salt-induced rigid and nonfunctional hydrophobic packing. Salt bridge interactions via increased negative and positive charges contribute to structural stability. Salt tolerance, conversely, is mediated by a dynamic structure that becomes more fixed and functional with increasing salt concentration. We propose that repulsive forces among excess negative charges, in addition to a high percentage of negatively charged random coils, mediate this structural dynamism. This knowledge enabled us to engineer a halophilic version of KOD DNA polymerase.-Takahashi, M., Takahashi, E., Joudeh, L. I., Marini, M., Das, G., Elshenawy, M. M., Akal, A., Sakashita, K., Alam, I., Tehseen, M., Sobhy, M. A., Stingl, U., Merzaban, J. S., Di Fabrizio, E., Hamdan, S. M. Dynamic structure mediates halophilic adaptation of a DNA polymerase from the deep-sea brines of the Red Sea.

Wet oxidation of GeSi strained layers by rapid thermal processing

NASA Astrophysics Data System (ADS)

Nayak, D. K.; Kamjoo, K.; Park, J. S.; Woo, J. C. S.; Wang, K. L.

1990-07-01

A cold-wall rapid thermal processor is used for the wet oxidation of the commensurately grown GexSi1-x layers on Si substrates. The rate of oxidation of the GexSi1-x layer is found to be significantly higher than that of pure Si, and the oxidation rate increases with the increase in the Ge content in GexSi1-x layer. The oxidation rate of GexSi1-x appears to decrease with increasing oxidation time for the time-temperature cycles considered here. Employing high-frequency and quasi-static capacitance-voltage measurements, it is found that a fixed negative oxide charge density in the range of 1011- 1012/cm2 and the interface trap level density (in the mid-gap region) of about 1012/cm2 eV are present. Further, the density of this fixed interface charge at the SiO2/GeSi interface is found to increase with the Ge concentration in the commensurately grown GeSi layers.

Effects of coating rectangular microscopic electrophoresis chamber with methylcellulose

NASA Technical Reports Server (NTRS)

Plank, L. D.

1985-01-01

One of the biggest problems in obtaining high accuracy in microscopic electrophoresis is the parabolic flow of liquid in the chamber due to electroosmotic backflow during application of the electric field. In chambers with glass walls the source of polarization leading to electroosmosis is the negative charge of the silicare and other ions that form the wall structure. It was found by Hjerten, who used a rotating 3.0 mm capillary tube for free zone electrophoresis, that precisely neutralizing this charge was extremely difficult, but if a neutral polymer matrix (formaldehyde fixed methylcellulose) was formed over the glass (quartz) wall the double layer was displaced and the viscosity at the shear plane increased so that electroosmotic flow could be eliminated. Experiments were designed to determine the reliability with which methylcellulose coating of the Zeiss Cytopherometer chamber reduced electroosmotic backflow and the effect of coating on the accuracy of cell electrophoretic mobility (EPN) determinations. Fixed rat erythrocytes (RBC) were used as test particles.

Electrostatic theory of the assembly of PAMAM dendrimers and DNA.

PubMed

Perico, Angelo

2016-05-01

The electrostatic interactions mediated by counterions between a cationic PAMAM dendrimer, modelized as a sphere of radius and cationic surface charge highly increasing with generation, and a DNA, modelized as an anionic elastic line, are analytically calculated in the framework of condensation theory. Under these interactions the DNA is wrapped around the sphere. For excess phosphates relative to dendrimer primary amines, the free energy of the DNA-dendrimer complex displays an absolute minimum when the complex is weakly negatively overcharged. This overcharging opposes gene delivery. For a highly positive dendrimer and a DNA fixed by experimental conditions to a number of phosphates less than the number of dendrimer primary amines, excess amine charges, the dendrimer may at the same time bind stably DNA and interact with negative cell membranes to activate cell transfection in fair agreement with molecular simulations and experiments. © 2016 Wiley Periodicals, Inc.

Dielectric boundary force and its crucial role in gramicidin

NASA Astrophysics Data System (ADS)

Nadler, Boaz; Hollerbach, Uwe; Eisenberg, R. S.

2003-08-01

In an electrostatic problem with nonuniform geometry, a charge Q in one region induces surface charges [called dielectric boundary charges (DBC)] at boundaries between different dielectrics. These induced surface charges, in return, exert a force [called dielectric boundary force (DBF)] on the charge Q that induced them. The DBF is often overlooked. It is not present in standard continuum theories of (point) ions in or near membranes and proteins, such as Gouy-Chapman, Debye-Huckel, Poisson-Boltzmann or Poisson-Nernst- Planck. The DBF is important when a charge Q is near dielectric interfaces, for example, when ions permeate through protein channels embedded in biological membranes. In this paper, we define the DBF and calculate it explicitly for a planar dielectric wall and for a tunnel geometry resembling the ionic channel gramicidin. In general, we formulate the DBF in a form useful for continuum theories, namely, as a solution of a partial differential equation with boundary conditions. The DBF plays a crucial role in the permeation of ions through the gramicidin channel. A positive ion in the channel produces a DBF of opposite sign to that of the fixed charge force (FCF) produced by the permanent charge of the gramicidin polypeptide, and so the net force on the positive ion is reduced. A negative ion creates a DBF of the same sign as the FCF and so the net (repulsive) force on the negative ion is increased. Thus, a positive ion can permeate the channel, while a negative ion is excluded from it. In gramicidin, it is this balance between the FCF and DBF that allows only singly charged positive ions to move into and through the channel. The DBF is not directly responsible, however, for selectivity between the alkali metal ions (e.g., Li+, Na+, K+): we prove that the DBF on a mobile spherical ion is independent of the ion’s radius.

Space Weather Influence on Relative Motion Control using the Touchless Electrostatic Tractor

NASA Astrophysics Data System (ADS)

Hogan, Erik A.; Schaub, Hanspeter

2016-09-01

With recent interest in the use of electrostatic forces for contactless tugging and attitude control of noncooperative objects for orbital servicing and active debris mitigation, the need for a method of remote charge control arises. In this paper, the use of a directed electron beam for remote charge control is considered in conjunction with the relative motion control. A tug vehicle emits an electron beam onto a deputy object, charging it negatively. At the same time, the tug is charged positively due to beam emission, resulting in an attractive electrostatic force. The relative position feedback control between the tug and the passive debris object is studied subject to the charging being created through an electron beam. Employing the nominal variations of the GEO space weather conditions across longitude slots, two electrostatic tugging strategies are considered. First, the electron beam current is adjusted throughout the orbit in order to maximize this resulting electrostatic force. This open-loop control strategy compensates for changes in the nominally expected local space weather environment in the GEO region to adjust for fluctuations in the local plasma return currents. Second, the performance impact of using a fixed electron beam current on the electrostatic tractor is studied if the same natural space weather variations are assumed. The fixed electron beam current shows a minor performance penalty (<5 %) while providing a much simpler implementation that does not require any knowledge of local space weather conditions.

13 CFR 120.213 - What fixed interest rates may a Lender charge?

Code of Federal Regulations, 2010 CFR

2010-01-01

... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false What fixed interest rates may a... BUSINESS LOANS Policies Specific to 7(a) Loans Maturities; Interest Rates; Loan and Guarantee Amounts § 120.213 What fixed interest rates may a Lender charge? (a) Fixed Rates for Guaranteed Loans. A loan may...

Insulator-semiconductor interface fixed charges in AlGaN/GaN metal-insulator-semiconductor devices with Al2O3 or AlTiO gate dielectrics

NASA Astrophysics Data System (ADS)

Le, Son Phuong; Nguyen, Duong Dai; Suzuki, Toshi-kazu

2018-01-01

We have investigated insulator-semiconductor interface fixed charges in AlGaN/GaN metal-insulator-semiconductor (MIS) devices with Al2O3 or AlTiO (an alloy of Al2O3 and TiO2) gate dielectrics obtained by atomic layer deposition on AlGaN. Analyzing insulator-thickness dependences of threshold voltages for the MIS devices, we evaluated positive interface fixed charges, whose density at the AlTiO/AlGaN interface is significantly lower than that at the Al2O3/AlGaN interface. This and a higher dielectric constant of AlTiO lead to rather shallower threshold voltages for the AlTiO gate dielectric than for Al2O3. The lower interface fixed charge density also leads to the fact that the two-dimensional electron concentration is a decreasing function of the insulator thickness for AlTiO, whereas being an increasing function for Al2O3. Moreover, we discuss the relationship between the interface fixed charges and interface states. From the conductance method, it is shown that the interface state densities are very similar at the Al2O3/AlGaN and AlTiO/AlGaN interfaces. Therefore, we consider that the lower AlTiO/AlGaN interface fixed charge density is not owing to electrons trapped at deep interface states compensating the positive fixed charges and can be attributed to a lower density of oxygen-related interface donors.

Instability analysis of charges trapped in the oxide of metal-ultra thin oxide-semiconductor structures

NASA Astrophysics Data System (ADS)

Aziz, A.; Kassmi, K.; Maimouni, R.; Olivié, F.; Sarrabayrouse, G.; Martinez, A.

2005-09-01

In this paper, we present the theoretical and experimental results of the influence of a charge trapped in ultra-thin oxide of metal/ultra-thin oxide/semiconductor structures (MOS) on the I(Vg) current-voltage characteristics when the conduction is of the Fowler-Nordheim (FN) tunneling type. The charge, which is negative, is trapped near the cathode (metal/oxide interface) after constant current injection by the metal (Vg<0). Of particular interest is the influence on the Δ Vg(Vg) shift over the whole I(Vg) characteristic at high field (greater than the injection field (>12.5 MV/cm)). It is shown that the charge centroid varies linearly with respect to the voltage Vg. The behavior at low field (<12.5 MV/cm) is analyzed in référence A. Aziz, K. Kassmi, Ka. Kassmi, F. Olivié, Semicond. Sci. Technol. 19, 877 (2004) and considers that the trapped charge centroid is fixed. The results obtained make it possible to analyze the influence of the injected charge and the applied field on the centroid position of the trapped charge, and to highlight the charge instability in the ultra-thin oxide of MOS structures.

Microgravity Experiments to Evaluate Electrostatic Forces in Controlling Cohesion and Adhesion of Granular Materials

NASA Technical Reports Server (NTRS)

Marshall, J.; Weislogel, M.; Jacobson, T.

1999-01-01

The bulk behavior of dispersed, fluidized, or undispersed stationary granular systems cannot be fully understood in terms of adhesive/cohesive properties without understanding the role of electrostatic forces acting at the level of the grains themselves. When grains adhere to a surface, or come in contact with one another in a stationary bulk mass, it is difficult to measure the forces acting on the grains, and the forces themselves that induced the cohesion and adhesion are changed. Even if a single grain were to be scrutinized in the laboratory, it might be difficult, perhaps impossible, to define the distribution and character of surface charging and the three-dimensional relationship that charges (electrons, holes) have to one another. The hypothesis that we propose to test in microgravity (for dielectric materials) is that adhesion and cohesion of granular matter are mediated primarily by dipole forces that do not require the presence of a net charge; in fact, nominally electrically neutral materials should express adhesive and cohesive behavior when the neutrality results from a balance of positive and negative charge carriers. Moreover, the use of net charge alone as a measure of the electrical nature of grain-to-grain relationships within a granular mass may be misleading. We believe that the dipole forces arise from the presence of randomly-distributed positive and negative fixed charge carriers on grains that give rise to a resultant dipole moment. These dipole forces have long-range attraction. Random charges are created whenever there is triboelectrical activity of a granular mass, that is, whenever the grains experience contact/separation sequences or friction.

Processing of n+/p-/p+ strip detectors with atomic layer deposition (ALD) grown Al2O3 field insulator on magnetic Czochralski silicon (MCz-si) substrates

NASA Astrophysics Data System (ADS)

Härkönen, J.; Tuovinen, E.; Luukka, P.; Gädda, A.; Mäenpää, T.; Tuominen, E.; Arsenovich, T.; Junkes, A.; Wu, X.; Li, Z.

2016-08-01

Detectors manufactured on p-type silicon material are known to have significant advantages in very harsh radiation environment over n-type detectors, traditionally used in High Energy Physics experiments for particle tracking. In p-type (n+ segmentation on p substrate) position-sensitive strip detectors, however, the fixed oxide charge in the silicon dioxide is positive and, thus, causes electron accumulation at the Si/SiO2 interface. As a result, unless appropriate interstrip isolation is applied, the n-type strips are short-circuited. Widely adopted methods to terminate surface electron accumulation are segmented p-stop or p-spray field implantations. A different approach to overcome the near-surface electron accumulation at the interface of silicon dioxide and p-type silicon is to deposit a thin film field insulator with negative oxide charge. We have processed silicon strip detectors on p-type Magnetic Czochralski silicon (MCz-Si) substrates with aluminum oxide (Al2O3) thin film insulator, grown with Atomic Layer Deposition (ALD) method. The electrical characterization by current-voltage and capacitance-voltage measurement shows reliable performance of the aluminum oxide. The final proof of concept was obtained at the test beam with 200 GeV/c muons. For the non-irradiated detector the charge collection efficiency (CCE) was nearly 100% with a signal-to-noise ratio (S/N) of about 40, whereas for the 2×1015 neq/cm2 proton irradiated detector the CCE was 35%, when the sensor was biased at 500 V. These results are comparable with the results from p-type detectors with the p-spray and p-stop interstrip isolation techniques. In addition, interestingly, when the aluminum oxide was irradiated with Co-60 gamma-rays, an accumulation of negative fixed oxide charge in the oxide was observed.

Role of Ions in the Regulation of Light-Harvesting

PubMed Central

Kaňa, Radek; Govindjee

2016-01-01

Regulation of photosynthetic light harvesting in the thylakoids is one of the major key factors affecting the efficiency of photosynthesis. Thylakoid membrane is negatively charged and influences both the structure and the function of the primarily photosynthetic reactions through its electrical double layer (EDL). Further, there is a heterogeneous organization of soluble ions (K+, Mg2+, Cl−) attached to the thylakoid membrane that, together with fixed charges (negatively charged amino acids, lipids), provides an electrical field. The EDL is affected by the valence of the ions and interferes with the regulation of “state transitions,” protein interactions, and excitation energy “spillover” from Photosystem II to Photosystem I. These effects are reflected in changes in the intensity of chlorophyll a fluorescence, which is also a measure of photoprotective non-photochemical quenching (NPQ) of the excited state of chlorophyll a. A triggering of NPQ proceeds via lumen acidification that is coupled to the export of positive counter-ions (Mg2+, K+) to the stroma or/and negative ions (e.g., Cl−) into the lumen. The effect of protons and anions in the lumen and of the cations (Mg2+, K+) in the stroma are, thus, functionally tightly interconnected. In this review, we discuss the consequences of the model of EDL, proposed by Barber (1980b) Biochim Biophys Acta 594:253–308) in light of light-harvesting regulation. Further, we explain differences between electrostatic screening and neutralization, and we emphasize the opposite effect of monovalent (K+) and divalent (Mg2+) ions on light-harvesting and on “screening” of the negative charges on the thylakoid membrane; this effect needs to be incorporated in all future models of photosynthetic regulation by ion channels and transporters. PMID:28018387

Passivation of phosphorus diffused silicon surfaces with Al2O3: Influence of surface doping concentration and thermal activation treatments

NASA Astrophysics Data System (ADS)

Richter, Armin; Benick, Jan; Kimmerle, Achim; Hermle, Martin; Glunz, Stefan W.

2014-12-01

Thin layers of Al2O3 are well known for the excellent passivation of p-type c-Si surfaces including highly doped p+ emitters, due to a high density of fixed negative charges. Recent results indicate that Al2O3 can also provide a good passivation of certain phosphorus-diffused n+ c-Si surfaces. In this work, we studied the recombination at Al2O3 passivated n+ surfaces theoretically with device simulations and experimentally for Al2O3 deposited with atomic layer deposition. The simulation results indicate that there is a certain surface doping concentration, where the recombination is maximal due to depletion or weak inversion of the charge carriers at the c-Si/Al2O3 interface. This pronounced maximum was also observed experimentally for n+ surfaces passivated either with Al2O3 single layers or stacks of Al2O3 capped by SiNx, when activated with a low temperature anneal (425 °C). In contrast, for Al2O3/SiNx stacks activated with a short high-temperature firing process (800 °C) a significant lower surface recombination was observed for most n+ diffusion profiles without such a pronounced maximum. Based on experimentally determined interface properties and simulation results, we attribute this superior passivation quality after firing to a better chemical surface passivation, quantified by a lower interface defect density, in combination with a lower density of negative fixed charges. These experimental results reveal that Al2O3/SiNx stacks can provide not only excellent passivation on p+ surfaces but also on n+ surfaces for a wide range of surface doping concentrations when activated with short high-temperature treatments.

Fragmentation of organic ions bearing fixed multiple charges observed in MALDI MS.

PubMed

Lou, Xianwen; Li, Bao; de Waal, Bas F M; Schill, Jurgen; Baker, Matthew B; Bovee, Ralf A A; van Dongen, Joost L J; Milroy, Lech-Gustav; Meijer, E W

2018-01-01

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) was used to analyze a series of synthetic organic ions bearing fixed multiple charges. Despite the multiple intrinsic charges, only singly charged ions were recorded in each case. In addition to the pseudo-molecular ions formed by counterion adduction, deprotonation and electron capture, a number of fragment ions were also observed. Charge splitting by fragmentation was found to be a viable route for charge reduction leading to the formation of the observed singly charged fragment ions. Unlike multivalent metal ions, organic ions can rearrange and/or fragment during charge reduction. This fragmentation process will evidently complicate the interpretation of the MALDI MS spectrum. Because MALDI MS is usually considered as a soft ionization technique, the fragment ion peaks can easily be erroneously interpreted as impurities. Therefore, the awareness and understanding of the underlying MALDI-induced fragmentation pathways is essential for a proper interpretation of the corresponding mass spectra. Due to the fragment ions generated during charge reduction, special care should be taken in the MALDI MS analysis of multiply charged ions. In this work, the possible mechanisms by which the organic ions bearing fixed multiple charges fragment are investigated. With an improved understanding of the fragmentation mechanisms, MALDI TOF MS should still be a useful technique for the characterization of organic ions with fixed multiple charges. Copyright © 2017 John Wiley & Sons, Ltd.

films on silicon at different annealing temperatures

NASA Astrophysics Data System (ADS)

Zhao, Yan; Zhou, Chunlan; Zhang, Xiang; Zhang, Peng; Dou, Yanan; Wang, Wenjing; Cao, Xingzhong; Wang, Baoyi; Tang, Yehua; Zhou, Su

2013-03-01

Thermal atomic layer-deposited (ALD) aluminum oxide (Al2O3) acquires high negative fixed charge density ( Q f) and sufficiently low interface trap density after annealing, which enables excellent surface passivation for crystalline silicon. Q f can be controlled by varying the annealing temperatures. In this study, the effect of the annealing temperature of thermal ALD Al2O3 films on p-type Czochralski silicon wafers was investigated. Corona charging measurements revealed that the Q f obtained at 300°C did not significantly affect passivation. The interface-trapping density markedly increased at high annealing temperature (>600°C) and degraded the surface passivation even at a high Q f. Negatively charged or neutral vacancies were found in the samples annealed at 300°C, 500°C, and 750°C using positron annihilation techniques. The Al defect density in the bulk film and the vacancy density near the SiO x /Si interface region decreased with increased temperature. Measurement results of Q f proved that the Al vacancy of the bulk film may not be related to Q f. The defect density in the SiO x region affected the chemical passivation, but other factors may dominantly influence chemical passivation at 750°C.

On the universality of thermodynamics and η/s ratio for the charged Lovelock black branes

NASA Astrophysics Data System (ADS)

Cadoni, Mariano; Frassino, Antonia M.; Tuveri, Matteo

2016-05-01

We investigate general features of charged Lovelock black branes by giving a detailed description of geometrical, thermodynamic and holographic properties of charged Gauss-Bonnet (GB) black branes in five dimensions. We show that when expressed in terms of effective physical parameters, the thermodynamic behaviour of charged GB black branes is completely indistinguishable from that of charged Einstein black branes. Moreover, the extremal, near-horizon limit of the two classes of branes is exactly the same as they allow for the same AdS2 × R 3, near-horizon, exact solution. This implies that, although in the UV the associated dual QFTs are different, they flow in the IR to the same fixed point. The calculation of the shear viscosity to entropy ratio η/s confirms these results. Despite the GB dual plasma has in general a non-universal temperature-dependent η/s, it flows monotonically to the universal value 1 /4 π in the IR. For negative (positive) GB coupling constant, η/s is an increasing (decreasing) function of the temperature and the flow respects (violates) the KSS bound.

Improvement of silicon solar cell efficiency by ion beam sputtered deposition of AlOxNy thin films.

PubMed

Chen, Sheng-Hui; Hsu, Chun-Che; Wang, Hsuan-Wen; Yeh, Chi-Li; Tseng, Shao-Ze; Lin, Hung-Ju; Lee, Cheng-Chung; Peng, Cheng-Yu

2011-03-20

Negative charge material, AlOxNy, has been fabricated to passivate the surface of p-type silicon. The fabrication of AlOxNy was possible by using ion beam sputtering deposition to deposit AlN thin film on the surface of a p-type silicon wafer and following annealing in oxygen ambient. Capacitance-voltage analysis shows the fixed charge density has increased from 10(11) cm(-2) to 2.26×10(12) cm(-2) after annealing. The solar cell efficiency increased from 15.9% to 17.3%, which is also equivalent to the reduction of surface recombination velocity from 1×10(5)  to 32 cm/s.

Electromagnetic instabilities in solar wind interaction with dusty cometary plasmas

NASA Technical Reports Server (NTRS)

Verheest, Frank; Meuris, Peter

1995-01-01

Dusty plasmas contain charged dust grains which are much more massive than protons, carry high negative charges due to preferential capture of electrons, and do not have a fixed charge. Fluctuations in the grain charges due to liberation or capture of additional electrons and protons translate as mass and momentum losses or gains for these species, which can render linear modes unstable. On the other hand, many authors have addressed the pickup of ions of cometary origin by the solar wind, which for the parallel part is due to relative streaming between cometary and solar wind ions which excites low-frequency electromagnetic turbulence. In the present work we look again at those instabilities by including effects due to the presence of charged dust in the cometary environments. We have investigated several frequency regimes: nonresonant below the cometary watergroup gyrofrequency, nonresonant below the cometary charged dust gyrofrequency (new and interesting but highly unlikely!) and resonant with the cometary watergroup ions. For most parameter ranges either the existing instabilities are enhanced, showing that the presence of charged dust facilitates the cometary ion pickup by the solar wind, or new instabilities have been shown to exist. Similar conclusions might be relevant for other kinds of astrophysical and heliospheric plasmas containing charged dust, as in planetary rings.

Fixed-Charge Atomistic Force Fields for Molecular Dynamics Simulations in the Condensed Phase: An Overview.

PubMed

Riniker, Sereina

2018-03-26

In molecular dynamics or Monte Carlo simulations, the interactions between the particles (atoms) in the system are described by a so-called force field. The empirical functional form of classical fixed-charge force fields dates back to 1969 and remains essentially unchanged. In a fixed-charge force field, the polarization is not modeled explicitly, i.e. the effective partial charges do not change depending on conformation and environment. This simplification allows, however, a dramatic reduction in computational cost compared to polarizable force fields and in particular quantum-chemical modeling. The past decades have shown that simulations employing carefully parametrized fixed-charge force fields can provide useful insights into biological and chemical questions. This overview focuses on the four major force-field families, i.e. AMBER, CHARMM, GROMOS, and OPLS, which are based on the same classical functional form and are continuously improved to the present day. The overview is aimed at readers entering the field of (bio)molecular simulations. More experienced users may find the comparison and historical development of the force-field families interesting.

Analysis of spacecraft battery charger systems

NASA Astrophysics Data System (ADS)

Kim, Seong J.; Cho, Bo H.

In spacecraft battery charger systems, switching regulators are widely used for bus voltage regulation, charge current regulation, and peak power tracking. Small-signal dynamic characteristics of the battery charging subsystem of direct energy transfer (DET) and peak power tracking (PPT) systems are analyzed to facilitate design of the control loop for optimum performance and stability. Control loop designs of the charger in various modes of operation are discussed. Analyses are verified through simulations. It is shown that when the charger operates in the bus voltage regulation mode, the control-to-voltage transfer function has a negative DC gain and two LHP zeros in both the DET and PPT systems. The control-to-inductor current transfer function also has a negative DC gain and a RHP zero. Thus, in the current-mode control, the current loop can no longer be used to stabilize the system. When the system operates in the charge current regulation mode, the charger operates with a fixed duty cycle which is determined by the regulated bus voltage and the battery voltage. Without an input filter, the converter becomes a first-order system. When the peak power tracker is inactive, the operating point of the solar array output moves to the voltage source region. Thus, the solar array behaves as a stiff voltage source to a constant power load.

Passivation mechanism of thermal atomic layer-deposited Al2O3 films on silicon at different annealing temperatures.

PubMed

Zhao, Yan; Zhou, Chunlan; Zhang, Xiang; Zhang, Peng; Dou, Yanan; Wang, Wenjing; Cao, Xingzhong; Wang, Baoyi; Tang, Yehua; Zhou, Su

2013-03-02

Thermal atomic layer-deposited (ALD) aluminum oxide (Al2O3) acquires high negative fixed charge density (Qf) and sufficiently low interface trap density after annealing, which enables excellent surface passivation for crystalline silicon. Qf can be controlled by varying the annealing temperatures. In this study, the effect of the annealing temperature of thermal ALD Al2O3 films on p-type Czochralski silicon wafers was investigated. Corona charging measurements revealed that the Qf obtained at 300°C did not significantly affect passivation. The interface-trapping density markedly increased at high annealing temperature (>600°C) and degraded the surface passivation even at a high Qf. Negatively charged or neutral vacancies were found in the samples annealed at 300°C, 500°C, and 750°C using positron annihilation techniques. The Al defect density in the bulk film and the vacancy density near the SiOx/Si interface region decreased with increased temperature. Measurement results of Qf proved that the Al vacancy of the bulk film may not be related to Qf. The defect density in the SiOx region affected the chemical passivation, but other factors may dominantly influence chemical passivation at 750°C.

Passivation mechanism of thermal atomic layer-deposited Al2O3 films on silicon at different annealing temperatures

PubMed Central

2013-01-01

Thermal atomic layer-deposited (ALD) aluminum oxide (Al2O3) acquires high negative fixed charge density (Qf) and sufficiently low interface trap density after annealing, which enables excellent surface passivation for crystalline silicon. Qf can be controlled by varying the annealing temperatures. In this study, the effect of the annealing temperature of thermal ALD Al2O3 films on p-type Czochralski silicon wafers was investigated. Corona charging measurements revealed that the Qf obtained at 300°C did not significantly affect passivation. The interface-trapping density markedly increased at high annealing temperature (>600°C) and degraded the surface passivation even at a high Qf. Negatively charged or neutral vacancies were found in the samples annealed at 300°C, 500°C, and 750°C using positron annihilation techniques. The Al defect density in the bulk film and the vacancy density near the SiOx/Si interface region decreased with increased temperature. Measurement results of Qf proved that the Al vacancy of the bulk film may not be related to Qf. The defect density in the SiOx region affected the chemical passivation, but other factors may dominantly influence chemical passivation at 750°C. PMID:23452508

Development of a multiplexed bypass control system for aerospace batteries

NASA Technical Reports Server (NTRS)

Frank, H. A.

1977-01-01

A breadboard bypass control system was developed to control a battery comprised of 26 JPL-developed negative limited Ni-Cd cells. The system was designed to automatically remove cells from the circuit when their voltages exceeded a fixed limit on charge and fell below a fixed limit on discharge. Major components of the system consisted of a cell voltage monitor, a multiplexing circuit, and individual electromechanical relays for each cell. The system was found to function well in controlling the battery during a simulated 10-month MM-71 mission and a 2-month simulated low earth orbit cycling mission. A flight version of the bypass system was estimated to have a total parts count of 150 and total weight of 1.63 kg. When fully developed, the system shows promise for improving life and reliability of spacecraft batteries.

Theoretical models for electron conduction in polymer systems—I. Macroscopic calculations of d.c. transient conductivity after pulse irradiation

NASA Astrophysics Data System (ADS)

Bartczak, Witold M.; Kroh, Jerzy

The simulation of the transient d.c. conductivity in a quasi one-dimensional system of charges produced by a pulse of ionizing radiation in a solid sample has been performed. The simulation is based on the macroscopic conductivity equations and can provide physical insight into d.c. conductivity measurements, particularly for the case of transient currents in samples with internal space charge. We consider the system of mobile (negative) and immobile (positive) charges produced by a pulse of ionizing radiation in the sample under a fixed external voltage V0. The presence of space charge results in an electric field which is a function of both the spatial and the time variable: E( z, t). Given the space charge density, the electric field can be calculated from the Poisson equation. However, for an arbitrary space charge distribution, the corresponding equations can only be solved numerically. The two non-trivial cases for which approximate analytical solutions can be provided are: (i) The density of the current carriers n( z, t) is negligible in comparison with the density of immobile space charge N( z). A general analytical solution has been found for this case using Green's functions. The solutions for two cases, viz. the homogeneous distribution of space charge N( z) = N, and the non-homogeneous exponential distribution N( z) = A exp(- Bz), have been separately discussed. (ii) The space charge created in the pulse without any space charge present prior to the irradiation.

A pH-tunable nanofluidic diode with a broad range of rectifying properties.

PubMed

Ali, Mubarak; Ramirez, Patricio; Mafé, Salvador; Neumann, Reinhard; Ensinger, Wolfgang

2009-03-24

The use of fixed charge nanopores in practical applications requires tuning externally the electrostatic interaction between the charged groups and the ionic permeants in order to allow integrating a variety of functions on the same nanostructure. We design, produce, and characterize, theoretically and experimentally, a single-track amphoteric nanopore functionalized with lysine and histidine chains whose positive and negative charges are very sensitive to the external pH. This nanofluidic diode with amphoteric chains attached to the pore surface allows for a broad set of rectification properties supported by a single nanodevice. A definite plus is to functionalize these groups on a conical nanopore with well-defined, controlled structural asymmetry which gives virtually every rectification characteristic that may be required in practical applications. Nanometerscaled amphoteric pores are of general interest because of the potential applications in drug delivery systems, ion-exchange membranes for separation of biomacromolecules, antifouling materials with reduced molecular adsorption, and biochemical sensors.

Avidin as a Model for Charge Driven Transport into Cartilage and Drug Delivery for treating Early Stage Post-traumatic Osteoarthritis

PubMed Central

Bajpayee, Ambika G.; Wong, Cliff R.; Bawendi, Moungi G.; Frank, Eliot H.; Grodzinsky, Alan J.

2013-01-01

Local drug delivery into cartilage remains a challenge due to its dense extracellular matrix of negatively charged proteoglycans enmeshed within a collagen fibril network. The high negative fixed charge density of cartilage offers the unique opportunity to utilize electrostatic interactions to augment transport, binding and retention of drug carriers. With the goal of developing particle-based drug delivery mechanisms for treating post-traumatic osteoarthritis, our objectives were, first, to determine the size range of a variety of solutes that could penetrate and diffuse through normal cartilage and enzymatically treated cartilage to mimic early stages of OA, and second, to investigate the effects of electrostatic interactions on particle partitioning, uptake and binding within cartilage using the highly positively charged protein, Avidin, as a model. Results showed that solutes having a hydrodynamic diameter ≤ 10 nm can penetrate into the full thickness of cartilage explants while larger sized solutes were trapped in the tissue’s superficial zone. Avidin had a 400-fold higher uptake than its neutral same-sized counterpart, NeutrAvidin, and >90% of the absorbed Avidin remained within cartilage explants for at least 15 days. We report reversible, weak binding (KD ~150 μM) of Avidin to intratissue sites in cartilage. The large effective binding site density (NT ~ 2920 μM) within cartilage matrix facilitates Avidin’s retention, making its structure suitable for particle based drug delivery into cartilage. PMID:24120044

Use of Sacrificial Nanoparticles to Remove the Effects of Shot-noise in Contact Holes Fabricated by E-beam Lithography.

PubMed

Rananavare, Shankar B; Morakinyo, Moshood K

2017-02-12

Nano-patterns fabricated with extreme ultraviolet (EUV) or electron-beam (E-beam) lithography exhibit unexpected variations in size. This variation has been attributed to statistical fluctuations in the number of photons/electrons arriving at a given nano-region arising from shot-noise (SN). The SN varies inversely to the square root of a number of photons/electrons. For a fixed dosage, the SN is larger in EUV and E-beam lithographies than for traditional (193 nm) optical lithography. Bottom-up and top-down patterning approaches are combined to minimize the effects of shot noise in nano-hole patterning. Specifically, an amino-silane surfactant self-assembles on a silicon wafer that is subsequently spin-coated with a 100 nm film of a PMMA-based E-beam photoresist. Exposure to the E-beam and the subsequent development uncover the underlying surfactant film at the bottoms of the holes. Dipping the wafer in a suspension of negatively charged, citrate-capped, 20 nm gold nanoparticles (GNP) deposits one particle per hole. The exposed positively charged surfactant film in the hole electrostatically funnels the negatively charged nanoparticle to the center of an exposed hole, which permanently fixes the positional registry. Next, by heating near the glass transition temperature of the photoresist polymer, the photoresist film reflows and engulfs the nanoparticles. This process erases the holes affected by SN but leaves the deposited GNPs locked in place by strong electrostatic binding. Treatment with oxygen plasma exposes the GNPs by etching a thin layer of the photoresist. Wet-etching the exposed GNPs with a solution of I2/KI yields uniform holes located at the center of indentations patterned by E-beam lithography. The experiments presented show that the approach reduces the variation in the size of the holes caused by SN from 35% to below 10%. The method extends the patterning limits of transistor contact holes to below 20 nm.

Passivation of phosphorus diffused silicon surfaces with Al{sub 2}O{sub 3}: Influence of surface doping concentration and thermal activation treatments

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

Richter, Armin, E-mail: armin.richter@ise.fraunhofer.de; Benick, Jan; Kimmerle, Achim

2014-12-28

Thin layers of Al{sub 2}O{sub 3} are well known for the excellent passivation of p-type c-Si surfaces including highly doped p{sup +} emitters, due to a high density of fixed negative charges. Recent results indicate that Al{sub 2}O{sub 3} can also provide a good passivation of certain phosphorus-diffused n{sup +} c-Si surfaces. In this work, we studied the recombination at Al{sub 2}O{sub 3} passivated n{sup +} surfaces theoretically with device simulations and experimentally for Al{sub 2}O{sub 3} deposited with atomic layer deposition. The simulation results indicate that there is a certain surface doping concentration, where the recombination is maximal duemore » to depletion or weak inversion of the charge carriers at the c-Si/Al{sub 2}O{sub 3} interface. This pronounced maximum was also observed experimentally for n{sup +} surfaces passivated either with Al{sub 2}O{sub 3} single layers or stacks of Al{sub 2}O{sub 3} capped by SiN{sub x}, when activated with a low temperature anneal (425 °C). In contrast, for Al{sub 2}O{sub 3}/SiN{sub x} stacks activated with a short high-temperature firing process (800 °C) a significant lower surface recombination was observed for most n{sup +} diffusion profiles without such a pronounced maximum. Based on experimentally determined interface properties and simulation results, we attribute this superior passivation quality after firing to a better chemical surface passivation, quantified by a lower interface defect density, in combination with a lower density of negative fixed charges. These experimental results reveal that Al{sub 2}O{sub 3}/SiN{sub x} stacks can provide not only excellent passivation on p{sup +} surfaces but also on n{sup +} surfaces for a wide range of surface doping concentrations when activated with short high-temperature treatments.« less

Impact of magnetite nanoparticle incorporation on optical and electrical properties of nanocomposite LbL assemblies.

PubMed

Yashchenok, Alexey M; Gorin, Dmitry A; Badylevich, Mikhail; Serdobintsev, Alexey A; Bedard, Matthieu; Fedorenko, Yanina G; Khomutov, Gennady B; Grigoriev, Dmitri O; Möhwald, Helmuth

2010-09-21

Optical and electrical properties of polyelectrolyte/iron oxide nanocomposite planar films on silicon substrates were investigated for different amount of iron oxide nanoparticles incorporated in the films. The nanocomposite assemblies prepared by the layer-by-layer assembly technique were characterized by ellipsometry, atomic force microscopy, and secondary ion mass-spectrometry. Absorption spectra of the films reveal a shift of the optical absorption edge to higher energy when the number of deposited layers decreases. Capacitance-voltage and current-voltage measurements were applied to study the electrical properties of metal-oxide-semiconductor structures prepared by thermal evaporation of gold electrodes on nanocomposite films. The capacitance-voltage measurements show that the dielectric constant of the film increases with the number of deposited layers and the fixed charge and the trapped charge densities have a negative sign.

33 CFR Appendix B to Part 277 - Hypothetical Example of Cost Apportionment

Code of Federal Regulations, 2013 CFR

2013-07-01

...) $165,489 I b. Fixed charges (owner's share) 284,460 II A fixed charge such as engineering, design and... new bridge is designed for increased loading and width greater than that of the old bridge. Therefore, the estimated annual maintenance cost was based on a hypothetical bridge designed, but not constructed...

33 CFR Appendix B to Part 277 - Hypothetical Example of Cost Apportionment

Code of Federal Regulations, 2014 CFR

2014-07-01

...) $165,489 I b. Fixed charges (owner's share) 284,460 II A fixed charge such as engineering, design and... new bridge is designed for increased loading and width greater than that of the old bridge. Therefore, the estimated annual maintenance cost was based on a hypothetical bridge designed, but not constructed...

33 CFR Appendix B to Part 277 - Hypothetical Example of Cost Apportionment

Code of Federal Regulations, 2010 CFR

2010-07-01

...) $165,489 I b. Fixed charges (owner's share) 284,460 II A fixed charge such as engineering, design and... new bridge is designed for increased loading and width greater than that of the old bridge. Therefore, the estimated annual maintenance cost was based on a hypothetical bridge designed, but not constructed...

33 CFR Appendix B to Part 277 - Hypothetical Example of Cost Apportionment

Code of Federal Regulations, 2011 CFR

2011-07-01

...) $165,489 I b. Fixed charges (owner's share) 284,460 II A fixed charge such as engineering, design and... new bridge is designed for increased loading and width greater than that of the old bridge. Therefore, the estimated annual maintenance cost was based on a hypothetical bridge designed, but not constructed...

33 CFR Appendix B to Part 277 - Hypothetical Example of Cost Apportionment

Code of Federal Regulations, 2012 CFR

2012-07-01

...) $165,489 I b. Fixed charges (owner's share) 284,460 II A fixed charge such as engineering, design and... new bridge is designed for increased loading and width greater than that of the old bridge. Therefore, the estimated annual maintenance cost was based on a hypothetical bridge designed, but not constructed...

Thin silicon layer SOI power device with linearly-distance fixed charge islands

NASA Astrophysics Data System (ADS)

Yuan, Zuo; Haiou, Li; Jianghui, Zhai; Ning, Tang; Shuxiang, Song; Qi, Li

2015-05-01

A new high-voltage LDMOS with linearly-distanced fixed charge islands is proposed (LFI LDMOS). A lot of linearly-distanced fixed charge islands are introduced by implanting the Cs or I ion into the buried oxide layer and dynamic holes are attracted and accumulated, which is crucial to enhance the electric field of the buried oxide and the vertical breakdown voltage. The surface electric field is improved by increasing the distance between two adjacent fixed charge islands from source to drain, which lead to the higher concentration of the drift region and a lower on-resistance. The numerical results indicate that the breakdown voltage of 500 V with Ld = 45 μm is obtained in the proposed device in comparison to 209 V of conventional LDMOS, while maintaining low on-resistance. Project supported by the Guangxi Natural Science Foundation of China (No. 2013GXNSFAA019335), the Guangxi Department of Education Project (No.201202ZD041), the China Postdoctoral Science Foundation Project (Nos. 2012M521127, 2013T60566), and the National Natural Science Foundation of China (Nos. 61361011, 61274077, 61464003).

Conformal Dimensions via Large Charge Expansion

NASA Astrophysics Data System (ADS)

Banerjee, Debasish; Chandrasekharan, Shailesh; Orlando, Domenico

2018-02-01

We construct an efficient Monte Carlo algorithm that overcomes the severe signal-to-noise ratio problems and helps us to accurately compute the conformal dimensions of large-Q fields at the Wilson-Fisher fixed point in the O (2 ) universality class. Using it, we verify a recent proposal that conformal dimensions of strongly coupled conformal field theories with a global U (1 ) charge can be obtained via a series expansion in the inverse charge 1 /Q . We find that the conformal dimensions of the lowest operator with a fixed charge Q are almost entirely determined by the first few terms in the series.

Conformal Dimensions via Large Charge Expansion.

PubMed

Banerjee, Debasish; Chandrasekharan, Shailesh; Orlando, Domenico

2018-02-09

We construct an efficient Monte Carlo algorithm that overcomes the severe signal-to-noise ratio problems and helps us to accurately compute the conformal dimensions of large-Q fields at the Wilson-Fisher fixed point in the O(2) universality class. Using it, we verify a recent proposal that conformal dimensions of strongly coupled conformal field theories with a global U(1) charge can be obtained via a series expansion in the inverse charge 1/Q. We find that the conformal dimensions of the lowest operator with a fixed charge Q are almost entirely determined by the first few terms in the series.

A Model-Based Investigation of Charge-Generation According to the Relative Diffusional Growth Rate Theory

NASA Astrophysics Data System (ADS)

Glassmeier, F.; Arnold, L.; Lohmann, U.; Dietlicher, R.; Paukert, M.

2016-12-01

Our current understanding of charge generation in thunderclouds is based on collisional charge transfer between graupel and ice crystals in the presence of liquid water droplets as dominant mechanism. The physical process of charge transfer and the sign of net charge generated on graupel and ice crystals under different cloud conditions is not yet understood. The Relative-Diffusional-Growth-Rate (RDGR) theory (Baker et al. 1987) suggests that the particle with the faster diffusional radius growth is charged positively. In this contribution, we use simulations of idealized thunderclouds with two-moment warm and cold cloud microphysics to generate realistic combinations of RDGR-parameters. We find that these realistic parameter combinations result in a relationship between sign of charge, cloud temperature and effective water content that deviates from previous theoretical and laboratory studies. This deviation indicates that the RDGR theory is sensitive to correlations between parameters that occur in clouds but are not captured in studies that vary temperature and water content while keeping other parameters at fixed values. In addition, our results suggest that diffusional growth from the riming-related local water vapor field, a key component of the RDGR theory, is negligible for realistic parameter combinations. Nevertheless, we confirm that the RDGR theory results in positive or negative charging of particles under different cloud conditions. Under specific conditions, charge generation via the RDGR theory alone might thus be sufficient to explain tripolar charge structures in thunderclouds. In general, however, additional charge generation mechanisms and adaptations to the RDGR theory that consider riming other than via local vapor deposition seem necessary.

Effect of alterations in glomerular charge on deposition of cationic and anionic antibodies to fixed glomerular antigens in the rat.

PubMed

Adler, S; Baker, P; Pritzl, P; Couser, W G

1985-07-01

Reduction of the negative charge of the glomerular capillary wall alters its charge- and size-selective properties. To investigate the effect of alteration in glomerular charge properties on antibody localization, we prepared cationic and anionic fractions of antibodies to subepithelial and glomerular basement membrane (GBM) antigens, and compared their deposition in normal rats and rats treated with protamine sulfate or aminonucleoside of puromycin to reduce capillary wall charge. IgG antibodies were eluted from kidneys of rats with active Heymann's nephritis (AICN), passive Heymann's nephritis (PHN), or anti-GBM nephritis (NTN), separated into cationic and anionic fractions, and radiolabeled with iodine 125 or iodine 131. Relative antibody content of each fraction was determined by incubation with an excess of glomerular antigen. Varying amounts of cationic and anionic IgG eluted from kidneys of rats with AICN or PHN were injected into 24 normal or protamine sulfate-treated rats. Glomerular binding of all antibodies was highly correlated with IgG delivery to the kidney. The ratio of cationic to anionic antibody deposited in the glomeruli of normal rats after 4 hours was 1.08 +/- 0.07 for AICN eluate and 0.37 +/- 0.04 for PHN eluate. The ratios were not significantly different in animals pretreated with protamine sulfate (1.15 +/- 0.06 and 0.44 +/- 0.06, respectively; P greater than 0.05). Varying amounts of cationic and anionic IgG eluted from kidneys of rats with NTN were injected into 10 normal rats and four rats treated with aminonucleoside of puromycin. Glomerular binding of antibody was again highly correlated with IgG delivery to the kidney. The ratio of cationic to anionic antibody deposited in the glomeruli of normal rats after 1 hour was 1.03 +/- 0.06, and was not significantly altered in rats treated with aminonucleoside of puromycin (1.05 +/- 0.03, P greater than 0.5). Proteinuria in PHN rats was also unaffected by treatment with protamine sulfate for 5 days (controls: 68 +/- 21 mg/day; protamine sulfate-treated: 65 +/- 14 mg/day; n = 25, P greater than 0.08). These results demonstrate that treatment to reduce glomerular polyanion does not significantly alter the ratio of cationic to anionic antibodies to fixed glomerular antigens that deposit in the glomerulus, or reduce proteinuria caused by deposition of antibody to a fixed subepithelial antigen.

17 CFR 229.503 - (Item 503) Prospectus summary, risk factors, and ratio of earnings to fixed charges.

Code of Federal Regulations, 2011 CFR

2011-04-01

..., risk factors, and ratio of earnings to fixed charges. 229.503 Section 229.503 Commodity and Securities... Registration Statement and Prospectus Provisions § 229.503 (Item 503) Prospectus summary, risk factors, and... executive offices. (c) Risk factors. Where appropriate, provide under the caption “Risk Factors” a...

17 CFR 229.503 - (Item 503) Prospectus summary, risk factors, and ratio of earnings to fixed charges.

Code of Federal Regulations, 2010 CFR

2010-04-01

..., risk factors, and ratio of earnings to fixed charges. 229.503 Section 229.503 Commodity and Securities... Registration Statement and Prospectus Provisions § 229.503 (Item 503) Prospectus summary, risk factors, and... executive offices. (c) Risk factors. Where appropriate, provide under the caption “Risk Factors” a...

Advanced passivation techniques for Si solar cells with high-κ dielectric materials

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

Geng, Huijuan; Lin, Tingjui; Letha, Ayra Jagadhamma

2014-09-22

Electronic recombination losses at the wafer surface significantly reduce the efficiency of Si solar cells. Surface passivation using a suitable thin dielectric layer can minimize the recombination losses. Herein, advanced passivation using simple materials (Al{sub 2}O{sub 3}, HfO{sub 2}) and their compounds H{sub (Hf)}A{sub (Al)}O deposited by atomic layer deposition (ALD) was investigated. The chemical composition of Hf and Al oxide films were determined by X-ray photoelectron spectroscopy (XPS). The XPS depth profiles exhibit continuous uniform dense layers. The ALD-Al{sub 2}O{sub 3} film has been found to provide negative fixed charge (−6.4 × 10{sup 11 }cm{sup −2}), whereas HfO{sub 2} film provides positivemore » fixed charge (3.2 × 10{sup 12 }cm{sup −2}). The effective lifetimes can be improved after oxygen gas annealing for 1 min. I-V characteristics of Si solar cells with high-κ dielectric materials as passivation layers indicate that the performance is significantly improved, and ALD-HfO{sub 2} film would provide better passivation properties than that of the ALD-Al{sub 2}O{sub 3} film in this research work.« less

Plasma flow around and charge distribution of a dust cluster in a rf discharge

NASA Astrophysics Data System (ADS)

Schleede, J.; Lewerentz, L.; Bronold, F. X.; Schneider, R.; Fehske, H.

2018-04-01

We employ a particle-in-cell Monte Carlo collision/particle-particle particle-mesh simulation to study the plasma flow around and the charge distribution of a three-dimensional dust cluster in the sheath of a low-pressure rf argon discharge. The geometry of the cluster and its position in the sheath are fixed to the experimental values, prohibiting a mechanical response of the cluster. Electrically, however, the cluster and the plasma environment, mimicking also the experimental situation, are coupled self-consistently. We find a broad distribution of the charges collected by the grains. The ion flux shows on the scale of the Debye length strong focusing and shadowing inside and outside the cluster due to the attraction of the ions to the negatively charged grains, whereas the electron flux is characterized on this scale only by a weak spatial modulation of its magnitude depending on the rf phase. On the scale of the individual dust potentials, however, the electron flux deviates in the vicinity of the cluster strongly from the laminar flow associated with the plasma sheath. It develops convection patterns to compensate for the depletion of electrons inside the dust cluster.

Raman scattering excitation spectroscopy of monolayer WS2.

PubMed

Molas, Maciej R; Nogajewski, Karol; Potemski, Marek; Babiński, Adam

2017-07-11

Resonant Raman scattering is investigated in monolayer WS 2 at low temperature with the aid of an unconventional technique, i.e., Raman scattering excitation (RSE) spectroscopy. The RSE spectrum is made up by sweeping the excitation energy, when the detection energy is fixed in resonance with excitonic transitions related to either neutral or charged excitons. We demonstrate that the shape of the RSE spectrum strongly depends on the selected detection energy. The resonance of outgoing light with the neutral exciton leads to an extremely rich RSE spectrum, which displays several Raman scattering features not reported so far, while no clear effect on the associated background photoluminescence is observed. Instead, when the outgoing photons resonate with the negatively charged exciton, a strong enhancement of the related emission occurs. Presented results show that the RSE spectroscopy can be a useful technique to study electron-phonon interactions in thin layers of transition metal dichalcogenides.

Tantalum oxide/silicon nitride: A negatively charged surface passivation stack for silicon solar cells

NASA Astrophysics Data System (ADS)

Wan, Yimao; Bullock, James; Cuevas, Andres

2015-05-01

This letter reports effective passivation of crystalline silicon (c-Si) surfaces by thermal atomic layer deposited tantalum oxide (Ta2O5) underneath plasma enhanced chemical vapour deposited silicon nitride (SiNx). Cross-sectional transmission electron microscopy imaging shows an approximately 2 nm thick interfacial layer between Ta2O5 and c-Si. Surface recombination velocities as low as 5.0 cm/s and 3.2 cm/s are attained on p-type 0.8 Ω.cm and n-type 1.0 Ω.cm c-Si wafers, respectively. Recombination current densities of 25 fA/cm2 and 68 fA/cm2 are measured on 150 Ω/sq boron-diffused p+ and 120 Ω/sq phosphorus-diffused n+ c-Si, respectively. Capacitance-voltage measurements reveal a negative fixed insulator charge density of -1.8 × 1012 cm-2 for the Ta2O5 film and -1.0 × 1012 cm-2 for the Ta2O5/SiNx stack. The Ta2O5/SiNx stack is demonstrated to be an excellent candidate for surface passivation of high efficiency silicon solar cells.

Electric potential calculation in molecular simulation of electric double layer capacitors

NASA Astrophysics Data System (ADS)

Wang, Zhenxing; Olmsted, David L.; Asta, Mark; Laird, Brian B.

2016-11-01

For the molecular simulation of electric double layer capacitors (EDLCs), a number of methods have been proposed and implemented to determine the one-dimensional electric potential profile between the two electrodes at a fixed potential difference. In this work, we compare several of these methods for a model LiClO4-acetonitrile/graphite EDLC simulated using both the traditional fixed-charged method (FCM), in which a fixed charge is assigned a priori to the electrode atoms, or the recently developed constant potential method (CPM) (2007 J. Chem. Phys. 126 084704), where the electrode charges are allowed to fluctuate to keep the potential fixed. Based on an analysis of the full three-dimensional electric potential field, we suggest a method for determining the averaged one-dimensional electric potential profile that can be applied to both the FCM and CPM simulations. Compared to traditional methods based on numerically solving the one-dimensional Poisson’s equation, this method yields better accuracy and no supplemental assumptions.

Penetration and release studies of positively and negatively charged nanoemulsions--is there a benefit of the positive charge?

PubMed

Baspinar, Yücel; Borchert, Hans-Hubert

2012-07-01

The surface of all tissues, including the stratum corneum, carries a negative charge. Following that fact it is assumed that a positively charged topical formulation could lead to an enhanced penetration because of an increased interaction with the negative charge of the membrane. The intention of this study is to prove an enhanced penetration of a positively charged nanoemulsion compared to a negatively charged nanoemulsion, both containing prednicarbate. The release and penetration of these nanoemulsions, produced with the high pressure homogenization method, were investigated. Regarding these results reveals that the release of the negatively charged formulation is higher compared to the positively charged nanoemulsion, while the penetration of the positively charged nanoemulsion is enhanced compared to the negatively charged formulation. The results of the investigated positively charged nanoemulsion containing prednicarbate show that its topical use could be advantageous for the therapy of atopic dermatitis, especially regarding phytosphingosine, which was responsible for the positive charge. Copyright © 2012 Elsevier B.V. All rights reserved.

Study on high breakdown voltage GaN-based vertical field effect transistor with interfacial charge engineering for power applications

NASA Astrophysics Data System (ADS)

Du, Jiangfeng; Liu, Dong; Liu, Yong; Bai, Zhiyuan; Jiang, Zhiguang; Liu, Yang; Yu, Qi

2017-11-01

A high voltage GaN-based vertical field effect transistor with interfacial charge engineering (GaN ICE-VFET) is proposed and its breakdown mechanism is presented. This vertical FET features oxide trenches which show a fixed negative charge at the oxide/GaN interface. In the off-state, firstly, the trench oxide layer acts as a field plate; secondly, the n-GaN buffer layer is inverted along the oxide/GaN interface and thus a vertical hole layer is formed, which acts as a virtual p-pillar and laterally depletes the n-buffer pillar. Both of them modulate electric field distribution in the device and significantly increase the breakdown voltage (BV). Compared with a conventional GaN vertical FET, the BV of GaN ICE-VFET is increased from 1148 V to 4153 V with the same buffer thickness of 20 μm. Furthermore, the proposed device achieves a great improvement in the tradeoff between BV and on-resistance; and its figure of merit even exceeds the GaN one-dimensional limit.

Nanomechanics of layer-by-layer polyelectrolyte complexes: a manifestation of ionic cross-links and fixed charges.

PubMed

Han, Biao; Chery, Daphney R; Yin, Jie; Lu, X Lucas; Lee, Daeyeon; Han, Lin

2016-01-28

This study investigates the roles of two distinct features of ionically cross-linked polyelectrolyte networks - ionic cross-links and fixed charges - in determining their nanomechanical properties. The layer-by-layer assembled poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA) network is used as the model material. The densities of ionic cross-links and fixed charges are modulated through solution pH and ionic strength (IS), and the swelling ratio, elastic and viscoelastic properties are quantified via an array of atomic force microscopy (AFM)-based nanomechanical tools. The roles of ionic cross-links are underscored by the distinctive elastic and viscoelastic nanomechanical characters observed here. First, as ionic cross-links are highly sensitive to solution conditions, the instantaneous modulus, E0, exhibits orders-of-magnitude changes upon pH- and IS-governed swelling, distinctive from the rubber elasticity prediction based on permanent covalent cross-links. Second, ionic cross-links can break and self-re-form, and this mechanism dominates force relaxation of PAH/PAA under a constant indentation depth. In most states, the degree of relaxation is >90%, independent of ionic cross-link density. The importance of fixed charges is highlighted by the unexpectedly more elastic nature of the network despite low ionic cross-link density at pH 2.0, IS 0.01 M. Here, the complex is a net charged, loosely cross-linked, where the degree of relaxation is attenuated to ≈50% due to increased elastic contribution arising from fixed charge-induced Donnan osmotic pressure. In addition, this study develops a new method for quantifying the thickness of highly swollen polymer hydrogel films. It also underscores important technical considerations when performing nanomechanical tests on highly rate-dependent polymer hydrogel networks. These results provide new insights into the nanomechanical characters of ionic polyelectrolyte complexes, and lay the ground for further investigation of their unique time-dependent properties.

Role of protein surface charge in monellin sweetness.

PubMed

Xue, Wei-Feng; Szczepankiewicz, Olga; Thulin, Eva; Linse, Sara; Carey, Jannette

2009-03-01

A small number of proteins have the unusual property of tasting intensely sweet. Despite many studies aimed at identifying their sweet taste determinants, the molecular basis of protein sweetness is not fully understood. Recent mutational studies of monellin have implicated positively charged residues in sweetness. In the present work, the effect of overall net charge was investigated using the complementary approach of negative charge alterations. Multiple substitutions of Asp/Asn and Glu/Gln residues radically altered the surface charge of single-chain monellin by removing six negative charges or adding four negative charges. Biophysical characterization using circular dichroism, fluorescence, and two-dimensional NMR demonstrates that the native fold of monellin is preserved in the variant proteins under physiological solution conditions although their stability toward chemical denaturation is altered. A human taste test was employed to determine the sweetness detection threshold of the variants. Removal of negative charges preserves monellin sweetness, whereas added negative charge has a large negative impact on sweetness. Meta-analysis of published charge variants of monellin and other sweet proteins reveals a general trend toward increasing sweetness with increasing positive net charge. Structural mapping of monellin variants identifies a hydrophobic surface predicted to face the receptor where introduced positive or negative charge reduces sweetness, and a polar surface where charges modulate long-range electrostatic complementarity.

Analyte concentration at the tip of a nanopipette.

PubMed

Calander, Nils

2009-10-15

Concentration of molecules within the tips of nanopipettes when applying a DC voltage is herein investigated using finite-element simulations. The ion concentrations and fluxes due to diffusion, electro-migration, and electro-osmotic flow, and the electric potential are determined by the simultaneous solution of the Nernst-Planck, Poisson, and Navier-Stokes equations within the water solution containing sodium and chloride ions and negatively charged molecules. The electric potential within the pipette glass wall is at the same time determined by the Poisson equation together with appropriate boundary conditions and accounts for a field effect through the wall. Fixed negative surface charge on both the internal and external glass surfaces of the nanopipette is included together with the field effect through the glass wall to account for the electric double layer and the electro-osmosis. The inclusion of the field effect through the pipette wall is new compared to previous modeling of similar structures and is shown to be crucial for the behavior at the tip. It is demonstrated that the concentration of molecules is a consequence of ionic charge accumulation at the tip screening the electric field, thereby slowing down the electrophoretic motion of the molecules, which is further slowed down or stopped by the oppositely directed electro-osmosis. It is also shown that the trapping is very sensitive to the properties of the molecule, that is, its electrophoretic mobility and diffusion coefficient, the properties of the pipette, the ionic strength of the solution, and the applied electric field.

Consideration of Cost of Care in Pediatric Emergency Transfer-An Opportunity for Improvement.

PubMed

Gattu, Rajender K; De Fee, Ann-Sophie; Lichenstein, Richard; Teshome, Getachew

2017-05-01

Pediatric interhospital transfers are an economic burden to the health care, especially when deemed unnecessary. Physicians may be unaware of the cost implications of pediatric emergency transfers. A cost analysis may be relevant to reduce cost. To characterize children transferred from outlying emergency departments (EDs) to pediatric ED (PED) with a specific focus on transfers who were discharged home in 12 hours or less after transfer without intervention in PED and analyze charges associated with them. Charts of 352 patients (age, 0-18 years) transferred from 31 outlying EDs to PED during July 2009 to June 2010 were reviewed. Data were collected on the range, unit charge and volume of services provided in PED, length of stay, and final disposition. The average charge per patient transfer is calculated based on unit charge times total service units per 1000 patients per year and divided by 1000. Hospital charges were divided into fixed and variable. Of 352 patients transferred, 108 (30.7%) were admitted to pediatric inpatient service, 42 (11.9%) to intensive care; 36 (10.2%) went to the operating room, and 166 (47.2%) were discharged home. The average hospital charge per transfer was US $4843. Most (89%) of the charges were fixed, and 11% were variable. One hundred one (28.7%) patients were discharged home from PED in 12 hours or less without intervention. The hospital charges for these transfers were US $489,143. Significant number of transfers was discharged 12 hours or less without any additional intervention in PED. Fixed charges contribute to majority of total charges. Cost saving can be achieved by preventing unnecessary transfer.

Chargeability measurements of selected pharmaceutical dry powders to assess their electrostatic charge control capabilities.

PubMed

Ramirez-Dorronsoro, Juan-Carlos; Jacko, Robert B; Kildsig, Dane O

2006-01-01

The purpose of this study was to develop an instrument (the Purdue instrument) and the corresponding methodologies to measure the electrostatic charge development (chargeability) of dry powders when they are in dynamic contact with stainless steel surfaces. The system used an inductive noncontact sensor located inside an aluminum Faraday cage and was optimized to measure the charging capabilities of a fixed volume of powder (0.5 cc). The chargeability of 5,5-diphenyl-hydantoin, calcium sulfate dihydrate, cimetidine, 3 grades of colloidal silicon dioxide, magnesium stearate, 4 grades of microcrystalline cellulose, salicylic acid, sodium carbonate, sodium salicylate, spray-dried lactose, and sulfinpyrazone were tested at 4 linear velocities, and the particle size distribution effect was assessed for 3 different grades of colloidal silicon dioxide and 4 different grades of microcrystalline cellulose. The chargeability values exhibited a linear relationship for the range of velocities studied, with colloidal silicon dioxide exhibiting the maximum negative chargeability and with spray-dried lactose being the only compound to exhibit positive chargeability. The instrument sensitivity was improved by a factor of 2 over the first generation version, and the electrostatic charge measurements were reproducible with relative standard deviations ranging from nondetectable to 33.7% (minimum of 3 replicates). These results demonstrate the feasibility of using the Purdue instrument to measure the electrostatic charge control capabilities of pharmaceutical dry powders with a reasonable level of precision.

An analysis of five negative sprite-parent discharges and their associated thunderstorm charge structures

NASA Astrophysics Data System (ADS)

Boggs, Levi D.; Liu, Ningyu; Splitt, Michael; Lazarus, Steven; Glenn, Chad; Rassoul, Hamid; Cummer, Steven A.

2016-01-01

In this study we analyze the discharge morphologies of five confirmed negative sprite-parent discharges and the associated charge structures of the thunderstorms that produced them. The negative sprite-parent lightning took place in two thunderstorms that were associated with a tropical disturbance in east central and south Florida. The first thunderstorm, which moved onshore in east central Florida, produced four of the five negative sprite-parent discharges within a period of 17 min, as it made landfall from the Atlantic Ocean. These negative sprite-parents were composed of bolt-from-the-blue (BFB), hybrid intracloud-negative cloud-to-ground (IC-NCG), and multicell IC-NCGs discharges. The second thunderstorm, which occurred inland over south Florida, produced a negative sprite-parent that was a probable hybrid IC-NCG discharge and two negative gigantic jets (GJs). Weakened upper positive charge with very large midlevel negative charge was inferred for both convective cells that initiated the negative-sprite-parent discharges. Our study suggests tall, intense convective systems with high wind shear at the middle to upper regions of the cloud accompanied by low cloud-to-ground (CG) flash rates promote these charge structures. The excess amount of midlevel negative charge results in these CG discharges transferring much more charge to ground than typical negative CG discharges. We find that BFB discharges prefer an asymmetrical charge structure that brings the negative leader exiting the upper positive charge region closer to the lateral positive screening charge layer. This may be the main factor in determining whether a negative leader exiting the upper positive region of the thundercloud forms a BFB or GJ.

Thermal stability of atomic layer deposition Al2O3 film on HgCdTe

NASA Astrophysics Data System (ADS)

Zhang, P.; Sun, C. H.; Zhang, Y.; Chen, X.; He, K.; Chen, Y. Y.; Ye, Z. H.

2015-06-01

Thermal stability of Atomic Layer Deposition Al2O3 film on HgCdTe was investigated by Al2O3 film post-deposition annealing treatment and Metal-Insulator-Semiconductor device low-temperature baking treatment. The effectiveness of Al2O3 film was evaluated by measuring the minority carrier lifetime and capacitance versus voltage characteristics. After annealing treatment, the minority carrier lifetime of the HgCdTe sample presented a slight decrease. Furthermore, the fixed charge density and the slow charge density decreased significantly in the annealed MIS device. After baking treatment, the fixed charge density and the slow charge density of the unannealed and annealed MIS devices decreased and increased, respectively.

Electrokinetic motion of a rectangular nanoparticle in a nanochannel

NASA Astrophysics Data System (ADS)

Movahed, Saeid; Li, Dongqing

2012-08-01

This article presents a theoretical study of electrokinetic motion of a negatively charged cubic nanoparticle in a three-dimensional nanochannel with a circular cross-section. Effects of the electrophoretic and the hydrodynamic forces on the nanoparticle motion are examined. Because of the large applied electric field over the nanochannel, the impact of the Brownian force is negligible in comparison with the electrophoretic and the hydrodynamic forces. The conventional theories of electrokinetics such as the Poisson-Boltzmann equation and the Helmholtz-Smoluchowski slip velocity approach are no longer applicable in the small nanochannels. In this study, and at each time step, first, a set of highly coupled partial differential equations including the Poisson-Nernst-Plank equation, the Navier-Stokes equations, and the continuity equation was solved to find the electric potential, ionic concentration field, and the flow field around the nanoparticle. Then, the electrophoretic and hydrodynamic forces acting on the negatively charged nanoparticle were determined. Following that, the Newton second law was utilized to find the velocity of the nanoparticle. Using this model, effects of surface electric charge of the nanochannel, bulk ionic concentration, the size of the nanoparticle, and the radius of the nanochannel on the nanoparticle motion were investigated. Increasing the bulk ionic concentration or the surface charge of the nanochannel will increase the electroosmotic flow, and hence affect the particle's motion. It was also shown that, unlike microchannels with thin EDL, the change in nanochannel size will change the EDL field and the ionic concentration field in the nanochannel, affecting the particle's motion. If the nanochannel size is fixed, a larger particle will move faster than a smaller particle under the same conditions.

An Analysis of Two Thunderstorms Producing Five Negative Sprites on 12 September 2014

NASA Astrophysics Data System (ADS)

Boggs, L.; Liu, N.; Splitt, M. E.; Lazarus, S. M.; Cummer, S. A.; Rassoul, H.

2015-12-01

We present a detailed analysis of the thunderstorms and the parent lightning discharge morphologies of five confirmed negative sprites taking place in two different thunderstorms. These two thunderstorms took place in east-central and south Florida on 12 September 2014. We utilized several lightning location networks, remote magnetic field measurements, dual polarization radar, and balloon borne soundings in our analysis. Each parent discharge was immediately preceded by intra-cloud (IC) discharges between the mid-level negative and upper positive charge regions. This either allowed a second upward negative leader to escape the upper positive charge region, or encouraged a downward negative leader to be initiated and connect with ground. The discharges found in this study support the findings of Lu et al., 2012 [JGR,117, D04212, 2012] that negative sprite-parent lightning consists primarily of hybrid intra-cloud negative cloud-to-ground (IC-NCG) and bolt-from-the-blue (BFB) lightning. Our work finds these unique discharges form in thunderstorms that have an excess of mid-level negative charge and weakened upper positive charge. Due to this charge structure, these unusual discharges transfer more charge to the ground than typical negative cloud-to-ground discharges. Our study suggests that the key difference separating bolt-from-the-blue and gigantic jet discharges is an asymmetric charge structure. This acts to bring the negative leader exiting the thundercloud closer to the lateral positive screening layer, encouraging the negative leader to turn towards ground. This investigation reveals IC discharges that involve multiple convective cells and come to ground as a negative CG discharge, a breed of hybrid IC-NCG discharges, also transfer more negative charge to ground than typical negative CG discharges and are able to initiate negative sprites. From this work, the charge structures mentioned above resulted from tall, intense convective cells with low CG flash rates with high wind shear in the mid to upper regions of the cloud. This acted to create a large reservoir of mid-level negative charge and create a general asymmetry to the charge structure. The wind shear in the upper regions also acted to weaken the upper positive charge by turbulent mixing with the upper negative screening charge layer.

The influence of charge and the distribution of charge in the polar region of phospholipids on the activity of UDP-glucuronosyltransferase.

PubMed

Zakim, D; Eibl, H

1992-07-05

Studies of the mechanism of lipid-induced regulation of the microsomal enzyme UDP-glucuronosyltransferase have been extended by examining the influence of charge within the polar region on the ability of lipids to activate delipidated pure enzyme. The effects of net negative charge, of charge separation in phosphocholine, and of the distribution of charge in the polar region of lipids were studied using the GT2p isoform isolated from pig liver. Prior experiments have shown that lipids with net negative charge inhibit the enzyme (Zakim, D., Cantor, M., and Eibl, H. (1988) J. Biol. Chem. 263, 5164-5169). The current experiments show that the extent of inhibition on a molar basis increases as the net negative charge increases from -1 to -2. The inhibitory effect of negatively charged lipids is on the functional state of the enzyme and is not due to electrostatic repulsion of negatively charged substrates of the enzyme. Although the inhibitory effect of net negative charge is removed when negative charge is balanced by a positive charge due to a quaternary nitrogen, neutrality of the polar region is not a sufficient condition for activation of the enzyme. In addition to a balance of charge between Pi and the quaternary nitrogen, the distance between the negative and positive charges and the orientation of the dipole created by them are critical for activation of GT2p. The negative and positive charges must be separated by the equivalent of three -CH2- groups for optimal activation by a lipid. Shortening this distance by one -CH2- unit leads to a lipid that is ineffective in activating the enzyme. Reversal of the orientation of the dipole in which the negative charge is on the polymethylene side of the lipid-water interface and the positive charge extends into water also produces a lipid that is not effective for activating GT2p. On the other hand, lipids with phosphoserine as the polar region, which has the "normal" P-N distance but carries a net negative charge, do not inhibit GT2p. This result again illustrates the importance of the dipole of phosphocholine for modulating the functional state of GT2p.

MODELING PARTICULATE CHARGING IN ESPS

EPA Science Inventory

In electrostatic precipitators there is a strong interaction between the particulate space charge and the operating voltage and current of an electrical section. Calculating either the space charge or the operating point when the other is fixed is not difficult, but calculating b...

The transfer behavior of different ions across anion and cation exchange membranes under vanadium flow battery medium

NASA Astrophysics Data System (ADS)

Sun, Jiawei; Li, Xianfeng; Xi, Xiaoli; Lai, Qinzhi; Liu, Tao; Zhang, Huamin

2014-12-01

The transfer behavior of different ions (V2+, V3+, VO2+, VO2+, H+, SO42-) across ion exchange membranes is investigated under vanadium flow battery (VFB) operating condition. VX-20 anion exchange membrane (AEM) and Nafion 115 cation exchange membrane (CEM) are selected to investigate the influence of fixed charged groups on the transfer behavior of different ions. The interaction between different ions and water is discussed in detail aiming to ascertain the variation of different ions in the charge-discharge process. Under the VFB medium, the transfer behavior and function of different ions are very different for the AEM and CEM. V2+ ions at the negative side accumulate when VFB is assembled with Nafion 115, while the VO2+ ions at the positive side accumulate for VX-20. The SO42- ions will transfer across Nafion 115 to balance the charges and the protons can balance the charges of VX-20. Finally the capacity fade mechanism of different membranes is investigated, showing that the capacity decay of VFB assembled with Nafion 115 mainly results from the cross mix of vanadium ions across the membrane, however, for VX-20, the side reactions can be the major reason. This paper provides important information about electrolyte for the application of VFB.

Impact of Alternative Rate Structures on Distributed Solar Customer Electricity Bills

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

McLaren, Joyce A

Electric utilities are increasingly proposing changes to residential rate structures, in order to address concerns about their inability to recover fixed system costs from customers with grid connected distributed generation. The most common proposals have been to increase fixed charges, set minimum bills or instigate residential demand charges. This presentation provides results of an analysis to explore how these rate design alternatives impact electricity bills for PV and non-PV customers.

Polarizability effects on the structure and dynamics of ionic liquids

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

Cavalcante, Ary de Oliveira, E-mail: arycavalcante@ufam.edu.br; Departamento de Química, Universidade Federal do Amazonas, Av. Rodrigo Octávio, 6200, Coroado, Manaus, AM; Ribeiro, Mauro C. C.

2014-04-14

Polarization effects on the structure and dynamics of ionic liquids are investigated using molecular dynamics simulations. Four different ionic liquids were simulated, formed by the anions Cl{sup −} and PF{sub 6}{sup −}, treated as single fixed charge sites, and the 1-n-alkyl-3-methylimidazolium cations (1-ethyl and 1-butyl-), which are polarizable. The partial charge fluctuation of the cations is provided by the electronegativity equalization model (EEM) and a complete parameter set for the cations electronegativity (χ) and hardness (J) is presented. Results obtained from a non-polarizable model for the cations are also reported for comparison. Relative to the fixed charged model, the equilibriummore » structure of the first solvation shell around the imidazolium cations shows that inclusion of EEM polarization forces brings cations closer to each other and that anions are preferentially distributed above and below the plane of the imidazolium ring. The polarizable model yields faster translational and reorientational dynamics than the fixed charges model in the rotational-diffusion regime. In this sense, the polarizable model dynamics is in better agreement with the experimental data.« less

Simulation of electric double-layer capacitors: evaluation of constant potential method

NASA Astrophysics Data System (ADS)

Wang, Zhenxing; Laird, Brian; Yang, Yang; Olmsted, David; Asta, Mark

2014-03-01

Atomistic simulations can play an important role in understanding electric double-layer capacitors (EDLCs) at a molecular level. In such simulations, typically the electrode surface is modeled using fixed surface charges, which ignores the charge fluctuation induced by local fluctuations in the electrolyte solution. In this work we evaluate an explicit treatment of charges, namely constant potential method (CPM)[1], in which the electrode charges are dynamically updated to maintain constant electrode potential. We employ a model system with a graphite electrode and a LiClO4/acetonitrile electrolyte, examined as a function of electrode potential differences. Using various molecular and macroscopic properties as metrics, we compare CPM simulations on this system to results using fixed surface charges. Specifically, results for predicted capacity, electric potential gradient and solvent density profile are identical between the two methods; However, ion density profiles and solvation structure yield significantly different results.

Determination of detonation parameters for liquid High Explosives

NASA Astrophysics Data System (ADS)

Mochalova, Valentina; Utkin, Alexander

2011-06-01

The experimental investigation of detonation parameters and reaction zone structure in liquid HE (bis-(2-fluoro-2,2-dinitroethyl)formal (FEFO), tetranitromethane (TNM), nitromethane (NM)) was conducted. Detonation front in TNM and NM was stable while the instability of detonation in FEFO was observed. Von Neumann spike was recorded for these HE and its parameters were determined. The different methods for C-J point determination were used for each HE. For FEFO reaction time τ was found from experiments with different charge diameters (τ is approximately equal to 300 ns); for TNM - at fixed diameter and different lengths of charges (τ ~ 200 ns); for NM - at fixed diameter and length of charges, but detonation initiation was carried out by different explosive charges (τ ~ 50 ns). It was found that in TNM the detonation velocity depends on charge diameter. Maximum value of reaction rate in investigated liquid HE was observed after shock jump and induction time was not recorded.

Determination of detonation parameters for liquid high explosives

NASA Astrophysics Data System (ADS)

Mochalova, Valentina; Utkin, Alexander

2012-03-01

The experimental investigation of detonation parameters and reaction zone structure in liquid HE (bis-(2-fluoro-2,2-dinitroethyl)formal (FEFO), tetranitromethane (TNM), nitromethane (NM)) was conducted by means of laser interferometer VISAR. Detonation front in TNM and NM was stable while the instability of detonation in FEFO was observed. The parameters of Von Neumann spike were determined for these HE. The different methods for C-J point determination were used for each HE. For FEFO reaction time t was found from experiments with different charge diameters (τ is approximately equal to 300 ns); for TNM - at fixed diameter and different lengths of charges (τ ≈ 200 ns); for NM - at fixed diameter and length of charges, but detonation initiation was carried out by different explosive charges (τ ≈ 50 ns). It was found that in TNM the detonation velocity depends on charge diameter. Maximum value of reaction rate in investigated liquid HE was observed after shock jump.

Applying electric field to charged and polar particles between metallic plates: extension of the Ewald method.

PubMed

Takae, Kyohei; Onuki, Akira

2013-09-28

We develop an efficient Ewald method of molecular dynamics simulation for calculating the electrostatic interactions among charged and polar particles between parallel metallic plates, where we may apply an electric field with an arbitrary size. We use the fact that the potential from the surface charges is equivalent to the sum of those from image charges and dipoles located outside the cell. We present simulation results on boundary effects of charged and polar fluids, formation of ionic crystals, and formation of dipole chains, where the applied field and the image interaction are crucial. For polar fluids, we find a large deviation of the classical Lorentz-field relation between the local field and the applied field due to pair correlations along the applied field. As general aspects, we clarify the difference between the potential-fixed and the charge-fixed boundary conditions and examine the relationship between the discrete particle description and the continuum electrostatics.

Payload charging events in the mesosphere and their impact on Langmuir type electric probes

NASA Astrophysics Data System (ADS)

Bekkeng, T. A.; Barjatya, A.; Hoppe, U.-P.; Pedersen, A.; Moen, J. I.; Friedrich, M.; Rapp, M.

2013-02-01

Three sounding rockets were launched from Andøya Rocket Range in the ECOMA campaign in December 2010. The aim was to study the evolution of meteoric smoke particles during a major meteor shower. Of the various instruments onboard the rocket payload, this paper presents the data from a multi-Needle Langmuir Probe (m-NLP) and a charged dust detector. The payload floating potential, as observed using the m-NLP instrument, shows charging events on two of the three flights. These charging events cannot be explained using a simple charging model, and have implications towards the use of fixed bias Langmuir probes on sounding rockets investigating mesospheric altitudes. We show that for a reliable use of a single fixed bias Langmuir probe as a high spatial resolution relative density measurement, each payload should also carry an additional instrument to measure payload floating potential, and an instrument that is immune to spacecraft charging and measures absolute plasma density.

Recovery curves of the surface electric field after lightning discharges occurring between the positive charge pocket and negative charge centre in a thundercloud

NASA Astrophysics Data System (ADS)

Pawar, S. D.; Kamra, A. K.

2002-12-01

Surface observations of the electric field recovery curves of the lightning discharges occurring between the positive charge pocket and negative main charge centre in an overhead thundercloud are reported. Such recovery curves are observed to have an additional step of very slow field-change observed at an after-discharge value of electric field equal to 5-6 kV m-1. The behavior of recovery curves is explained in terms of the coronae charge and the relative efficiencies of the charge generating processes responsible for growth of positive charge pocket and main negative charge centre in the thundercloud. The charging currents responsible for the growth of charge in positive charge pockets is computed to be 2-4 times larger than that for the growth of the main negative charge. However, the charge destroyed in such a discharge is found to be comparable to that in a discharge between the main charge centres of the thundercloud.

Effect of ultraviolet illumination on the charge trapping behaviour in SiN(x)/InP metal-insulator-semiconductor structure provided by plasma enhanced chemical vapour deposition

NASA Astrophysics Data System (ADS)

Kim, C. H.; Han, I. K.; Lee, J. I.; Kang, K. N.; Kwon, S. D.; Choe, B.; Park, H. L.; Her, J.; Lim, H.

1994-04-01

In this work, we investigated the effect of ultraviolet illumination, which is known to generate silicon dangling bonds, on the charge trapping behaviors, utilizing the constant capacitance technique in SiN(x)/InP structure where conventional PE CVD was used to form the SiN films on InP. We found different behaviors of this structure with ultraviolet illumination compared to the case of SiN(x)/Si structure. Both the Si-rich condition during PE CVD and ultraviolet illumination seem to not only increase the number of traps but also broaden the energy level of the traps in the insulator near the SiN(x)/InP interface. In all cases (N-rich, Si-rich, with and without ultraviolet illumination) the amphoteric nature of the traps has been observed, which is a characteristic of Si-dangling bonds. Also, the effect of ultraviolet photons on the interface of SiN(x)/InP, especially in correlation with the deficiency of phosphorus at the interface, is discussed considering the existence of net negative fixed charges at the interface.

Is the negative glow plasma of a direct current glow discharge negatively charged?

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

Bogdanov, E. A.; Saifutdinov, A. I.; Demidov, V. I., E-mail: Vladimir.Demidov@mail.wvu.edu

A classic problem in gas discharge physics is discussed: what is the sign of charge density in the negative glow region of a glow discharge? It is shown that traditional interpretations in text-books on gas discharge physics that states a negative charge of the negative glow plasma are based on analogies with a simple one-dimensional model of discharge. Because the real glow discharges with a positive column are always two-dimensional, the transversal (radial) term in divergence with the electric field can provide a non-monotonic axial profile of charge density in the plasma, while maintaining a positive sign. The numerical calculationmore » of glow discharge is presented, showing a positive space charge in the negative glow under conditions, where a one-dimensional model of the discharge would predict a negative space charge.« less

Thunderstorm Charge Structures Producing Negative Gigantic Jets

NASA Astrophysics Data System (ADS)

Boggs, L.; Liu, N.; Riousset, J. A.; Shi, F.; Rassoul, H.

2016-12-01

Here we present observational and modeling results that provide insight into thunderstorm charge structures that produce gigantic jet discharges. The observational results include data from four different thunderstorms producing 9 negative gigantic jets from 2010 to 2014. We used radar, very high frequency (VHF) and low frequency (LF) lightning data to analyze the storm characteristics, charge structures, and lightning activity when the gigantic jets emerged from the parent thunderstorms. A detailed investigation of the evolution of one of the charge structures by analyzing the VHF data is also presented. The newly found charge structure obtained from the observations was analyzed with fractal modeling and compared with previous fractal modeling studies [Krehbiel et al., Nat. Geosci., 1, 233-237, 2008; Riousset et al., JGR, 115, A00E10, 2010] of gigantic jet discharges. Our work finds that for normal polarity thunderstorms, gigantic jet charge structures feature a narrow upper positive charge region over a wide middle negative charge region. There also likely exists a `ring' of negative screening charge located around the perimeter of the upper positive charge. This is different from previously thought charge structures of the storms producing gigantic jets, which had a very wide upper positive charge region over a wide middle negative charge region, with a very small negative screening layer covering the cloud top. The newly found charge structure results in leader discharge trees in the fractal simulations that closely match the parent flashes of gigantic jets inside and outside the thundercloud. The previously used charge structures, while vital to the understanding of gigantic jet initiation and the role of charge imbalances inside the cloud, do not produce leader discharge trees that agree with observed gigantic jet discharges.Finally, the newly discovered gigantic jet charge structures are formed near the end of a convective pulse [Meyer et al., JGR, 118, 2013; Lazarus et al., JGR, 120, 8469-8490, 2015] that pushes the negative screening charge radially outward and causes mixing around the updraft.

Genetics Home Reference: SLC4A1-associated distal renal tubular acidosis

MedlinePlus

... exchanger 1 (AE1) protein, which transports negatively charged atoms (anions) across cell membranes. Specifically, AE1 exchanges negatively charged atoms of chlorine (chloride ions) for negatively charged bicarbonate ...

Performance of time-varying predictors in multilevel models under an assumption of fixed or random effects.

PubMed

Baird, Rachel; Maxwell, Scott E

2016-06-01

Time-varying predictors in multilevel models are a useful tool for longitudinal research, whether they are the research variable of interest or they are controlling for variance to allow greater power for other variables. However, standard recommendations to fix the effect of time-varying predictors may make an assumption that is unlikely to hold in reality and may influence results. A simulation study illustrates that treating the time-varying predictor as fixed may allow analyses to converge, but the analyses have poor coverage of the true fixed effect when the time-varying predictor has a random effect in reality. A second simulation study shows that treating the time-varying predictor as random may have poor convergence, except when allowing negative variance estimates. Although negative variance estimates are uninterpretable, results of the simulation show that estimates of the fixed effect of the time-varying predictor are as accurate for these cases as for cases with positive variance estimates, and that treating the time-varying predictor as random and allowing negative variance estimates performs well whether the time-varying predictor is fixed or random in reality. Because of the difficulty of interpreting negative variance estimates, 2 procedures are suggested for selection between fixed-effect and random-effect models: comparing between fixed-effect and constrained random-effect models with a likelihood ratio test or fitting a fixed-effect model when an unconstrained random-effect model produces negative variance estimates. The performance of these 2 procedures is compared. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Effects of dc bias on the kinetics and electrical properties of silicon dioxide grown in an electron cyclotron resonance plasma

NASA Astrophysics Data System (ADS)

Carl, D. A.; Hess, D. W.; Lieberman, M. A.; Nguyen, T. D.; Gronsky, R.

1991-09-01

Thin (3-300-nm) oxides were grown on single-crystal silicon substrates at temperatures from 523 to 673 K in a low-pressure electron cyclotron resonance (ECR) oxygen plasma. Oxides were grown under floating, anodic or cathodic bias conditions, although only the oxides grown under floating or anodic bias conditions are acceptable for use as gate dielectrics in metal-oxide-semiconductor technology. Oxide thickness uniformity as measured by ellipsometry decreased with increasing oxidation time for all bias conditions. Oxidation kinetics under anodic conditions can be explained by negatively charged atomic oxygen, O-, transport limited growth. Constant current anodizations yielded three regions of growth: (1) a concentration gradient dominated regime for oxides thinner than 10 nm, (2) a field dominated regime with ohmic charged oxidant transport for oxide thickness in the range of 10 nm to approximately 100 nm, and (3) a space-charge limited regime for films thicker than approximately 100 nm. The relationship between oxide thickness (xox), overall potential drop (Vox) and ion current (ji) in the space-charge limited transport region was of the form: ji ∝ V2ox/x3ox. Transmission electron microscopy analysis of 5-60-nm-thick anodized films indicated that the silicon-silicon dioxide interface was indistinguishable from that of thermal oxides grown at 1123 K. High-frequency capacitance-voltage (C-V) and ramped bias current-voltage (I-V) studies performed on 5.4-30-nm gate thickness capacitors indicated that the as-grown ECR films had high levels of fixed oxide charge (≳1011 cm-2) and interface traps (≳1012 cm-2 eV-1). The fixed charge level could be reduced to ≊4×1010 cm-2 by a 20 min polysilicon gate activation anneal at 1123 K in nitrogen; the interface trap density at mid-band gap decreased to ≊(1-2)×1011 cm-2 eV-1 after this process. The mean breakdown strength for anodic oxides grown under optimum conditions was 10.87±0.83 MV cm-1. Electrical properties of the 5.4-8-nm gates compared well with thicker films and control dry thermal oxides of similar thicknesses.

Interstitial distribution of charged macromolecules in the dog lung: a kinetic model.

PubMed

Parker, J C; Miniati, M; Pitt, R; Taylor, A E

1987-01-01

A mathematic model was constructed to investigate conflicting physiologic data concerning the charge effect of continuous capillaries to macromolecules in the lung. We simulated the equilibration kinetics of lactate dehydrogenase (MR 4.2 nM) isozymes LDH 1 (pI = 5.0) and LDH 5 (pI = 7.9) between plasma and lymph using previously measured permeability coefficients, lung tissue distribution volumes (VA) and plasma concentrations (CP) in lung tissue. Our hypothesis is that the fixed anionic charges in interstitium, basement membrane, and cell surfaces determine equilibration rather than charged membrane effects at the capillary barrier, so the same capillary permeability coefficients were used for both isozymes. Capillary filtration rates and protein fluxes were calculated using conventional flux equations. Initial conditions at baseline and increased left atrial pressures (PLA) were those measured in animal studies. Simulated equilibration of isozymes over 30 h in the model at baseline capillary pressures accurately predicted the observed differences in lymph/plasma concentration ratios (CL/CP) between isotopes at 4 h and equilibration of these ratios at 24 h. Quantitative prediction of isozyme CL/CP ratios was also obtained at increased PLA. However, an additional cation selective compartment representing the surface glycocalyx was required to accurately simulate the initial higher transcapillary clearances of cationic LDH 5. Thus experimental data supporting the negative barrier, positive barrier, and no charge barrier hypotheses were accurately reproduced by the model using only the observed differences in interstitial partitioning of isozymes without differences in capillary selectivity.

Fixed interface charges between AlGaN barrier and gate stack composed of in situ grown SiN and Al{sub 2}O{sub 3} in AlGaN/GaN high electron mobility transistors with normally off capability

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

Capriotti, M., E-mail: mattia.capriotti@tuwien.ac.at; Alexewicz, A.; Fleury, C.

2014-03-17

Using a generalized extraction method, the fixed charge density N{sub int} at the interface between in situ deposited SiN and 5 nm thick AlGaN barrier is evaluated by measurements of threshold voltage V{sub th} of an AlGaN/GaN metal insulator semiconductor high electron mobility transistor as a function of SiN thickness. The thickness of the originally deposited 50 nm thick SiN layer is reduced by dry etching. The extracted N{sub int} is in the order of the AlGaN polarization charge density. The total removal of the in situ SiN cap leads to a complete depletion of the channel region resulting in V{sub th} = +1 V.more » Fabrication of a gate stack with Al{sub 2}O{sub 3} as a second cap layer, deposited on top of the in situ SiN, is not introducing additional fixed charges at the SiN/Al{sub 2}O{sub 3} interface.« less

Modeling and simulation of deformation of hydrogels responding to electric stimulus.

PubMed

Li, Hua; Luo, Rongmo; Lam, K Y

2007-01-01

A model for simulation of pH-sensitive hydrogels is refined in this paper to extend its application to electric-sensitive hydrogels, termed the refined multi-effect-coupling electric-stimulus (rMECe) model. By reformulation of the fixed-charge density and consideration of finite deformation, the rMECe model is able to predict the responsive deformations of the hydrogels when they are immersed in a bath solution subject to externally applied electric field. The rMECe model consists of nonlinear partial differential governing equations with chemo-electro-mechanical coupling effects and the fixed-charge density with electric-field effect. By comparison between simulation and experiment extracted from literature, the model is verified to be accurate and stable. The rMECe model performs quantitatively for deformation analysis of the electric-sensitive hydrogels. The influences of several physical parameters, including the externally applied electric voltage, initial fixed-charge density, hydrogel strip thickness, ionic strength and valence of surrounding solution, are discussed in detail on the displacement and average curvature of the hydrogels.

Effect of low thermal budget annealing on surface passivation of silicon by ALD based aluminum oxide films.

PubMed

Vandana; Batra, Neha; Gope, Jhuma; Singh, Rajbir; Panigrahi, Jagannath; Tyagi, Sanjay; Pathi, P; Srivastava, S K; Rauthan, C M S; Singh, P K

2014-10-21

Thermal ALD deposited Al2O3 films on silicon show a marked difference in surface passivation quality as a function of annealing time (using a rapid thermal process). An effective and quality passivation is realized in short anneal duration (∼100 s) in nitrogen ambient which is reflected in the low surface recombination velocity (SRV <10 cm s(-1)). The deduced values are close to the best reported SRV obtained by the high thermal budget process (with annealing time between 10-30 min), conventionally used for improved surface passivation. Both as-deposited and low thermal budget annealed films show the presence of positive fixed charges and this is never been reported in the literature before. The role of field and chemical passivation is investigated in terms of fixed charge and interface defect densities. Further, the importance of the annealing step sequence in the MIS structure fabrication protocol is also investigated from the view point of its effect on the nature of fixed charges.

Charge transfer in TATB and HMX under extreme conditions.

PubMed

Zhang, Chaoyang; Ma, Yu; Jiang, Daojian

2012-11-01

Charge transfer is usually accompanied by structural changes in materials under different conditions. However, the charge transfer in energetic materials that are subjected to extreme conditions has seldom been explored by researchers. In the work described here, the charge transfer in single molecules and unit cells of the explosives TATB and HMX under high temperatures and high pressures was investigated by performing static and dynamic calculations using three DFT methods, including the PWC functional of LDA, and the BLYP and PBE functionals of GGA. The results showed that negative charge is transferred from the nitro groups of molecular or crystalline TATB and HMX when they are heated. All DFT calculations for the compressed TATB unit cell indicate that, generally, negative charge transfer occurs to its nitro groups as the compression increases. PWC and PBE calculations for crystalline HMX show that negative charge is first transferred to the nitro groups but, as the compression increases, the negative charge is transferred from the nitro groups. However, the BLYP calculations indicated that there was gradual negative charge transfer to the nitro groups of HMX, similar to the case for TATB. The unrelaxed state of the uniformly compressed TATB causes negative charge to be transferred from its nitro groups, in contrast to what is seen in the relaxed state. Charge transfer in TATB is predicted to occur much more easily than in HMX.

Investigation of the W and Q 2 dependence of charged pion distributions in μ p scattering

NASA Astrophysics Data System (ADS)

Arneodo, M.; Arvidson, A.; Aubert, J. J.; Badelek, B.; Beaufays, J.; Bee, C. P.; Benchouk, C.; Berghoff, G.; Bird, I.; Blum, D.; Böhm, E.; de Bouard, X.; Brasse, F. W.; Braun, H.; Broll, C.; Brown, S.; Brück, H.; Calen, H.; Chima, J. S.; Ciborowski, J.; Clifft, R.; Coignet, G.; Combley, F.; Coughlan, J.; D'Agostini, G.; Dahlgren, S.; Dengler, F.; Derado, I.; Dreyer, T.; Drees, J.; Düren, M.; Eckardt, V.; Edwards, A.; Ernst, T.; Eszes, G.; Favier, J.; Ferrero, M. I.; Figiel, J.; Flauger, W.; Foster, J.; Gabathuler, E.; Gajewski, J.; Gamet, R.; Gayler, J.; Geddes, N.; Giubellino, P.; Grafström, P.; Grard, F.; Haas, J.; Hagberg, E.; Hasert, F. J.; Hayman, P.; Heusse, P.; Hoppe, C.; Jaffré, M.; Jacholkowska, A.; Janata, F.; Jancso, G.; Johnson, A. S.; Kabuss, E. M.; Kellner, G.; Korbel, V.; Krüger, J.; Kullander, S.; Landgraf, U.; Lanske, D.; Loken, J.; Long, K.; Maire, M.; Malecki, P.; Manz, A.; Maselli, S.; Mohr, W.; Montanet, F.; Montgomery, H. E.; Nagy, E.; Nassalski, J.; Norton, P. R.; Oakham, F. G.; Osborne, A. M.; Pascaud, C.; Pawlik, B.; Payre, P.; Peroni, C.; Pessard, H.; Pettingale, J.; Pietrzyk, B.; Pönsgen, B.; Pötsch, M.; Renton, P.; Ribarics, P.; Rith, K.; Rondio, E.; Scheer, M.; Schlagböhmer, A.; Schiemann, H.; Schmitz, N.; Schneegans, M.; Scholz, M.; Schröder, T.; Schouten, M.; Schultze, K.; Sloan, T.; Stier, H. E.; Studt, M.; Taylor, G. N.; Thénard, J. M.; Thompson, J. C.; de La Torre, A.; Toth, J.; Urban, L.; Wallucks, W.; Whalley, M.; Wheeler, S.; Williams, W. S. C.; Wimpenny, S. J.; Windmolders, R.; Wolf, G.

1986-03-01

The W and Q 2 dependence of the fragmentation functions and of the average multiplicity of charged pions is investigated, using data from the NA9 experiment at the CERN SPS on muon-proton scattering at 280 GeV. A significant increase of pion production with increasing W is observed at fixed Q 2, leading to a rise of the average charged pion multiplicity, linear in ln W 2, and of the pion fragmentation function in the central region, i.e. at small | x F |. This increase can be understood from the kinematic widening of the cms rapidity range proportional to ln W 2 and the observed W independent height of the rapidity distribution. At fixed W, a rise of the average charged pion multiplicity with Q 2 is observed. This rise appears to be weaker than that observed for all charged hadrons implying a stronger rise with Q 2 for kaons and protons.

78 FR 25115 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Notice of Filing of Proposed...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-29

... Amending the Mortgage-Backed Securities Division Fails Charge Rule To Reflect Recommendation of the... change is to amend the existing fails charge rule in FICC's Mortgage-Backed Securities Division (``MBSD... (``TMPG'') relating to the removal of the resolution period for fails charges.\\3\\ \\3\\ The text of the...

Trapped charge densities in Al{sub 2}O{sub 3}-based silicon surface passivation layers

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

Jordan, Paul M., E-mail: Paul.Jordan@namlab.com; Simon, Daniel K.; Dirnstorfer, Ingo

2016-06-07

In Al{sub 2}O{sub 3}-based passivation layers, the formation of fixed charges and trap sites can be strongly influenced by small modifications in the stack layout. Fixed and trapped charge densities are characterized with capacitance voltage profiling and trap spectroscopy by charge injection and sensing, respectively. Al{sub 2}O{sub 3} layers are grown by atomic layer deposition with very thin (∼1 nm) SiO{sub 2} or HfO{sub 2} interlayers or interface layers. In SiO{sub 2}/Al{sub 2}O{sub 3} and HfO{sub 2}/Al{sub 2}O{sub 3} stacks, both fixed charges and trap sites are reduced by at least a factor of 5 compared with the value measured inmore » pure Al{sub 2}O{sub 3}. In Al{sub 2}O{sub 3}/SiO{sub 2}/Al{sub 2}O{sub 3} or Al{sub 2}O{sub 3}/HfO{sub 2}/Al{sub 2}O{sub 3} stacks, very high total charge densities of up to 9 × 10{sup 12} cm{sup −2} are achieved. These charge densities are described as functions of electrical stress voltage, time, and the Al{sub 2}O{sub 3} layer thickness between silicon and the HfO{sub 2} or the SiO{sub 2} interlayer. Despite the strong variation of trap sites, all stacks reach very good effective carrier lifetimes of up to 8 and 20 ms on p- and n-type silicon substrates, respectively. Controlling the trap sites in Al{sub 2}O{sub 3} layers opens the possibility to engineer the field-effect passivation in the solar cells.« less

Observation and analysis of electrical structure change and diversity in thunderstorms on the Qinghai-Tibet Plateau

NASA Astrophysics Data System (ADS)

Li, Yajun; Zhang, Guangshu; Wang, Yanhui; Wu, Bin; Li, Jing

2017-09-01

A comprehensive observation on thunderstorms was conducted in the Qinghai area by using a very high frequency three-dimensional lightning mapping system and Doppler radar. The spatio-temporal evolution of the charge structure of the isolated thunderstorm was analyzed according to the developing process of thunderstorm, and the reasons for the change in charge structure diversity were studied. During the initial developing and mature stages of the thunderstorm, the charge structure was a steady negative dipole polarity, i.e., the negative charge region was above the positive charge region. Furthermore, the total number of flashes was lower during these two stages. During the thunderstorm's dissipation stage, the charge structure was varied and complicated, with a positive dipole, negative dipole, and a tripole charge structure changing and coexisting during this stage. This charge structure diversity was primarily caused by the collision and merging of two local thunderstorm cells, leading to a charge rearrangement and distribution and the formation of a new charge structure. The frequency of the negative cloud-to-ground and intracloud flashes increased sharply in the dissipation stage, reaching a maximum value. The increase in frequency of negative cloud-to-ground was mainly caused by the lower positive charge weakening during the dissipation stage. In addition, the relationship between charging regions and temperature layers was analyzed by combining sounding temperature data with the theory of a non-inductive charging mechanism.

The surface properties of Shewanella putrefaciens 200 and S. oneidensis MR-1: the effect of pH and terminal electron acceptors.

PubMed

Furukawa, Yoko; Dale, Jason R

2013-04-08

We investigated the surface characteristics of two strains of Shewanella sp., S. oneidensis MR-1 and S. putrefaciens 200, that were grown under aerobic conditions as well as under anaerobic conditions with trimethylamine oxide (TMAO) as the electron acceptor. The investigation focused on the experimental determination of electrophoretic mobility (EPM) under a range of pH and ionic strength, as well as by subsequent modeling in which Shewanella cells were considered to be soft particles with water- and ion-permeable outermost layers. The soft layer of p200 is significantly more highly charged (i.e., more negative) than that of MR-1. The effect of electron acceptor on the soft particle characteristics of Shewanella sp. is complex. The fixed charge density, which is a measure of the deionized and deprotonated functional groups in the soft layer polymers, is slightly greater (i.e., more negative) for aerobically grown p200 than for p200 grown with TMAO. On the other hand, the fixed charge density of aerobically grown MR1 is slightly less than that of p200 grown with TMAO. The effect of pH on the soft particle characteristics is also complex, and does not exhibit a clear pH-dependent trend. The Shewanella surface characteristics were attributed to the nature of the outermost soft layer, the extracellular polymeric substances (EPS) in case of p200 and lypopolysaccharides (LPS) in case of MR1 which generally lacks EPS. The growth conditions (i.e., aerobic vs. anaerobic TMAO) have an influence on the soft layer characteristics of Shewanella sp. cells. Meanwhile, the clear pH dependency of the mechanical and morphological characteristics of EPS and LPS layers, observed in previous studies through atomic force microscopy, adhesion tests and spectroscopies, cannot be corroborated by the electrohydrodynamics-based soft particle characteristics which does not exhibited a clear pH dependency in this study. While the electrohydrodynamics-based soft-particle model is a useful tool in understanding bacteria's surface properties, it needs to be supplemented with other characterization methods and models (e.g., chemical and micromechanical) in order to comprehensively address all of the surface-related characteristics important in environmental and other aqueous processes.

News on mean pion multiplicity from NA61/SHINE

NASA Astrophysics Data System (ADS)

Naskręt, Michał

2018-02-01

NA61/SHINE is a large acceptance fixed target experiment at the CERN SPS which studies final hadronic states in interactions between various particles and nuclei [1]. The main topic of this contribution are preliminary results for mean negatively charged pion multiplicities 〈π-〉 from central Ar+Sc and Be+Be collisions. The data were taken recently by the NA61/SHINE collaboration for a wide range of beam momenta. Measured rapidity distributions were extrapolated to unmeasured regions to obtain total multiplicities 〈π-〉 A new scheme to calculate the mean number of wounded nucleons 〈W〉 utilizing the EPOS MC model is described. Using data from other experiments, a comparison of for different collisions and beam momenta is discussed.

Intermetallic negative electrodes for non-aqueous lithium cells and batteries

DOEpatents

Thackeray, Michael M.; Vaughey, John T.; Johnson, Christopher S.; Fransson, Linda M.; Edstrom, Ester Kristina; Henriksen, Gary

2004-05-04

A method of operating an electrochemical cell is disclosed. The cell has an intermetallic negative electrode of Cu.sub.6-x M.sub.x Sn.sub.5, wherein x is .ltoreq.3 and M is one or more metals including Si and a positive electrode containing Li in which Li is shuttled between the positive electrode and the negative electrode during charge and discharge to form a lithiated intermetallic negative electrode during charge. The voltage of the electrochemical cell is controlled during the charge portion of the charge-discharge cycles so that the potential of the lithiated intermetallic negative electrode in the fully charged electrochemical cell is less than 0.2 V but greater than 0 V versus metallic lithium.

Multiphasic modeling of charged solute transport across articular cartilage: Application of multi-zone finite-bath model.

PubMed

Arbabi, Vahid; Pouran, Behdad; Weinans, Harrie; Zadpoor, Amir A

2016-06-14

Charged and uncharged solutes penetrate through cartilage to maintain the metabolic function of chondrocytes and to possibly restore or further breakdown the cartilage tissue in different stages of osteoarthritis. In this study the transport of charged solutes across the various zones of cartilage was quantified, taken into account the physicochemical interactions between the solute and the cartilage constituents. A multiphasic finite-bath finite element (FE) model was developed to simulate equine cartilage diffusion experiments that used a negatively charged contrast agent (ioxaglate) in combination with serial micro-computed tomography (micro-CT) to measure the diffusion. By comparing the FE model with the experimental data both the diffusion coefficient of ioxaglate and the fixed charge density (FCD) were obtained. In the multiphasic model, cartilage was divided into multiple (three) zones to help understand how diffusion coefficient and FCD vary across cartilage thickness. The direct effects of charged solute-FCD interaction on diffusion were investigated by comparing the diffusion coefficients derived from the multiphasic and biphasic-solute models. We found a relationship between the FCD obtained by the multiphasic model and ioxaglate partitioning obtained from micro-CT experiments. Using our multi-zone multiphasic model, diffusion coefficient of the superficial zone was up to ten-fold higher than that of the middle zone, while the FCD of the middle zone was up to almost two-fold higher than that of the superficial zone. In conclusion, the developed finite-bath multiphasic model provides us with a non-destructive method by which we could obtain both diffusion coefficient and FCD of different cartilage zones. The outcomes of the current work will also help understand how charge of the bath affects the diffusion of a charged molecule and also predict the diffusion behavior of a charged solute across articular cartilage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Polarization spectroscopy of positive and negative trions in an InAs quantum dot

NASA Astrophysics Data System (ADS)

Ware, Morgan E.; Bracker, Allan S.; Stinaff, Eric; Gammon, Daniel; Gershoni, David; Korenev, Vladimir L.

2005-02-01

Using polarization-sensitive photoluminescence and photoluminescence excitation spectroscopy, we study single InAs/GaAs self-assembled quantum dots. The dots were embedded in an n-type, Schottky diode structure allowing for control of the charge state. We present here the exciton, singly charged exciton (positive and negative trions), and the twice negatively charged exciton. For non-resonant excitation below the wetting layer, we observed a large degree of polarization memory from the radiative recombination of both the positive and negative trions. In excitation spectra, through the p-shell, we have found several sharp resonances in the emission from the s-shell recombination of the dot in all charged states. Some of these excitation resonances exhibit strong coulomb shifts upon addition of charges into the quantum dot. One particular resonance of the negatively charged trion was found to exhibit a fine structure doublet under circular polarization. This observation is explained in terms of resonant absorption into the triplet states of the negative trion.

Over-injection and self-oscillations in an electron vacuum diode

NASA Astrophysics Data System (ADS)

Leopold, J. G.; Siman-Tov, M.; Goldman, A.; Krasik, Ya. E.

2017-07-01

We demonstrate a practical means by which one can inject more than the space-charge limiting current into a vacuum diode. This over-injection causes self-oscillations of the space-charge resulting in an electron beam current modulation at a fixed frequency, a reaction of the system to the Coulomb repulsive forces due to charge accumulation.

18 CFR 11.14 - Procedures for establishing charges without an energy gains investigation.

Code of Federal Regulations, 2010 CFR

2010-04-01

... hydrology or project development, that affect headwater benefits. (2) Any procedures that apply to § 11.17(b)(5) of this subpart will apply to any prospectively fixed charges that are continued under this...

18 CFR 11.14 - Procedures for establishing charges without an energy gains investigation.

Code of Federal Regulations, 2011 CFR

2011-04-01

... hydrology or project development, that affect headwater benefits. (2) Any procedures that apply to § 11.17(b)(5) of this subpart will apply to any prospectively fixed charges that are continued under this...

Interface trap and oxide charge generation under negative bias temperature instability of p-channel metal-oxide-semiconductor field-effect transistors with ultrathin plasma-nitrided SiON gate dielectrics

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

Zhu Shiyang; Nakajima, Anri; Ohashi, Takuo

2005-12-01

The interface trap generation ({delta}N{sub it}) and fixed oxide charge buildup ({delta}N{sub ot}) under negative bias temperature instability (NBTI) of p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) with ultrathin (2 nm) plasma-nitrided SiON gate dielectrics were studied using a modified direct-current-current-voltage method and a conventional subthreshold characteristic measurement. Different stress time dependences were shown for {delta}N{sub it} and {delta}N{sub ot}. At the earlier stress times, {delta}N{sub it} dominates the threshold voltage shift ({delta}V{sub th}) and {delta}N{sub ot} is negligible. With increasing stress time, the rate of increase of {delta}N{sub it} decreases continuously, showing a saturating trend for longer stress times, while {delta}N{submore » ot} still has a power-law dependence on stress time so that the relative contribution of {delta}N{sub ot} increases. The thermal activation energy of {delta}N{sub it} and the NBTI lifetime of pMOSFETs, compared at a given stress voltage, are independent of the peak nitrogen concentration of the SiON film. This indicates that plasma nitridation is a more reliable method for incorporating nitrogen in the gate oxide.« less

Electrokinetics of diffuse soft interfaces. 1. Limit of low Donnan potentials.

PubMed

Duval, Jérôme F L; van Leeuwen, Herman P

2004-11-09

The current theoretical approaches to electrokinetics of gels or polyelectrolyte layers are based on the assumption that the position of the very interface between the aqueous medium and the gel phase is well defined. Within this assumption, spatial profiles for the volume fraction of polymer segments (phi), the density of fixed charges in the porous layer (rho fix), and the coefficient modeling the friction to hydrodynamic flow (k) follow a step-function. In reality, the "fuzzy" nature of the charged soft layer is intrinsically incompatible with the concept of a sharp interface and therefore necessarily calls for more detailed spatial representations for phi, rho fix, and k. In this paper, the notion of diffuse interface is introduced. For the sake of illustration, linear spatial distributions for phi and rho fix are considered in the interfacial zone between the bulk of the porous charged layer and the bulk electrolyte solution. The corresponding distribution for k is inferred from the Brinkman equation, which for low phi reduces to Stokes' equation. Linear electrostatics, hydrodynamics, and electroosmosis issues are analytically solved within the context of streaming current and streaming potential of charged surface layers in a thin-layer cell. The hydrodynamic analysis clearly demonstrates the physical incorrectness of the concept of a discrete slip plane for diffuse interfaces. For moderate to low electrolyte concentrations and nanoscale spatial transition of phi from zero (bulk electrolyte) to phi o (bulk gel), the electrokinetic properties of the soft layer as predicted by the theory considerably deviate from those calculated on the basis of the discontinuous approximation by Ohshima.

Negative differential mobility for negative carriers as revealed by space charge measurements on crosslinked polyethylene insulated model cables

NASA Astrophysics Data System (ADS)

Teyssedre, G.; Vu, T. T. N.; Laurent, C.

2015-12-01

Among features observed in polyethylene materials under relatively high field, space charge packets, consisting in a pulse of net charge that remains in the form of a pulse as it crosses the insulation, are repeatedly observed but without complete theory explaining their formation and propagation. Positive charge packets are more often reported, and the models based on negative differential mobility(NDM) for the transport of holes could account for some charge packets phenomenology. Conversely, NDM for electrons transport has never been reported so far. The present contribution reports space charge measurements by pulsed electroacoustic method on miniature cables that are model of HVDC cables. The measurements were realized at room temperature or with a temperature gradient of 10 °C through the insulation under DC fields on the order 30-60 kV/mm. Space charge results reveal systematic occurrence of a negative front of charges generated at the inner electrode that moves toward the outer electrode at the beginning of the polarization step. It is observed that the transit time of the front of negative charge increases, and therefore the mobility decreases, with the applied voltage. Further, the estimated mobility, in the range 10-14-10-13 m2 V-1 s-1 for the present results, increases when the temperature increases for the same condition of applied voltage. The features substantiate the hypothesis of negative differential mobility used for modelling space charge packets.

Method of adhesion between an oxide layer and a metal layer

DOEpatents

Jennison, Dwight R.; Bogicevic, Alexander; Kelber, Jeffry A.; Chambers, Scott A.

2004-09-14

A method of controlling the wetting characteristics and increasing the adhesion between a metal and an oxide layer. By introducing a negatively-charged species to the surface of an oxide layer, layer-by-layer growth of metal deposited onto the oxide surface is promoted, increasing the adhesion strength of the metal-oxide interface. The negatively-charged species can either be deposited onto the oxide surface or a compound can be deposited that dissociates on, or reacts with, the surface to form the negatively-charged species. The deposited metal adatoms can thereby bond laterally to the negatively-charged species as well as vertically to the oxide surface as well as react with the negatively charged species, be oxidized, and incorporated on or into the surface of the oxide.

Retrieval of charge mobility from apparent charge packet movements in LDPE thin films

NASA Astrophysics Data System (ADS)

Meng, Jia; Zhang, Yewen; Holé, Stéphane; Zheng, Feihu; An, Zhenlian

2017-03-01

The charge packet phenomenon observed in polyethylene materials has been reported extensively during the last decades. To explain its movement, Negative Differential Mobility (NDM) theory is a competitive model among several proposed mechanisms. However, as a key concept of this theory, a sufficiently acute relationship between charge mobility and electric field has never been reported until now, which makes it hard to precisely describe the migration of charge packets with this theory. Based on the substantial negative-charge packet observations with a sufficiently by wide electric field range from 15 kV/mm to 50 kV/mm, the present contribution successfully retrieved the negative-charge mobility from the apparent charge packet movements, which reveals a much closer relationship between the NDM theory and charge packet migrations. Back simulations of charge packets with the retrieved charge mobility offer a good agreement with the experimental data.

Scaling of Device Variability and Subthreshold Swing in Ballistic Carbon Nanotube Transistors

NASA Astrophysics Data System (ADS)

Cao, Qing; Tersoff, Jerry; Han, Shu-Jen; Penumatcha, Ashish V.

2015-08-01

In field-effect transistors, the inherent randomness of dopants and other charges is a major cause of device-to-device variability. For a quasi-one-dimensional device such as carbon nanotube transistors, even a single charge can drastically change the performance, making this a critical issue for their adoption as a practical technology. Here we calculate the effect of the random charges at the gate-oxide surface in ballistic carbon nanotube transistors, finding good agreement with the variability statistics in recent experiments. A combination of experimental and simulation results further reveals that these random charges are also a major factor limiting the subthreshold swing for nanotube transistors fabricated on thin gate dielectrics. We then establish that the scaling of the nanotube device uniformity with the gate dielectric, fixed-charge density, and device dimension is qualitatively different from conventional silicon transistors, reflecting the very different device physics of a ballistic transistor with a quasi-one-dimensional channel. The combination of gate-oxide scaling and improved control of fixed-charge density should provide the uniformity needed for large-scale integration of such novel one-dimensional transistors even at extremely scaled device dimensions.

Optimization of microelectrophoresis to select highly negatively charged sperm.

PubMed

Simon, Luke; Murphy, Kristin; Aston, Kenneth I; Emery, Benjamin R; Hotaling, James M; Carrell, Douglas T

2016-06-01

The sperm membrane undergoes extensive surface remodeling as it matures in the epididymis. During this process, the sperm is encapsulated in an extensive glycocalyx layer, which provides the membrane with its characteristic negative electrostatic charge. In this study, we develop a method of microelectrophoresis and standardize the protocol to isolate sperm with high negative membrane charge. Under an electric field, the percentage of positively charged sperm (PCS), negatively charged sperm (NCS), and neutrally charged sperm was determined for each ejaculate prior to and following density gradient centrifugation (DGC), and evaluated for sperm DNA damage, and histone retention. Subsequently, PCS, NCS, and neutrally charged sperm were selected using an ICSI needle and directly analyzed for DNA damage. When raw semen was analyzed using microelectrophoresis, 94 % were NCS. In contrast, DGC completely or partially stripped the negative membrane charge from sperm resulting PCS and neutrally charged sperm, while the charged sperm populations are increased with an increase in electrophoretic current. Following DGC, high sperm DNA damage and abnormal histone retention were inversely correlated with percentage NCS and directly correlated with percentage PCS. NCS exhibited significantly lower DNA damage when compared with control (P < 0.05) and PCS (P < 0.05). When the charged sperm population was corrected for neutrally charged sperm, sperm DNA damage was strongly associated with NCS at a lower electrophoretic current. The results suggest that selection of NCS at lower current may be an important biomarker to select healthy sperm for assisted reproductive treatment.

Charging of dust grains in a plasma with negative ions

NASA Astrophysics Data System (ADS)

Kim, Su-Hyun; Merlino, Robert L.

2006-05-01

The effect of negative ions on the charging of dust particles in a plasma is investigated experimentally. A plasma containing a very low percentage of electrons is formed in a single-ended SF6 is admitted into the vacuum system. The relatively cold (Te≈0.2eV ) readily attach to SF6 molecules to form SF6- negative ions. Calculations of the dust charge indicate that for electrons, negative ions, and positive ions of comparable temperatures, the charge (or surface potential) of the dust can be positive if the positive ion mass is smaller than the negative ion mass and if ɛ, the ratio of the electron to positive ion density, is sufficiently small. The K+ positive ions (mass 39amu) and SF6- negative ions (mass 146amu), and also utilizes a rotating cylinder to dispense dust into the plasma column. Analysis of the current-voltage characteristics of a Langmuir probe in the dusty plasma shows evidence for the reduction in the (magnitude) of the negative dust charge and the transition to positively charged dust as the relative concentration of the residual electrons is reduced. Some remarks are offered concerning experiments that could become possible in a dusty plasma with positive grains.

Devices that can identify positive vs. negative charge

NASA Astrophysics Data System (ADS)

Lincoln, James

2017-10-01

When your clothes come out of the dryer, covered with static, do you know whether they are positively or negatively charged? In this article, I discuss a variety of devices that can determine sign of the charge on an insulator or conductor. Purposefully, none of these methods utilize comparison with a known charge. Some of these ideas have been previously published, and I am extending them, but many are original. These demonstrations provide students and teachers with an opportunity to contrast the actual flow of charge with conventional current and to compare the behavior of positive and negative charges with what we expect from protons and electrons.

Lightning Channels of Cloud-to-Ground Flashes Neutralizing Multiple Charge Regions Inside Winter Thunderclouds

NASA Astrophysics Data System (ADS)

Akita, Manabu; Yoshida, Satoru; Nakamura, Yoshitaka; Morimoto, Takeshi; Ushio, Tomoo; Kawasaki, Zen-Ichiro; Wang, Daohong

Lightning Research Group of Osaka University (LRG-OU) has been developing and improving the VHF broadband digital interferometer (DITF) for thunderstorm observations. It enables us to locate the impulsive VHF radiation sources caused by lightning discharges with extremely high resolutions. As a result of the VHF observations during the 2007-2008 winter season in the Japan Sea coastal area, cloud-to-ground (CG) flashes that neutralize multiple charge regions inside thunderclouds are visualized by the VHF broadband DITF. The first flash is the positive CG flash that neutralizes multiple positive charge regions in a flash. The second flash is the bipolar lightning flash that neutralizes both positive and negative charge inside thunderclouds. In the case of bipolar lightning flashes, some tens millisecond after the return strokes, the subsequent negative breakdowns initiate from the proximities of the initiation points of the preceding negative stepped leaders. It was also found that the altitudes of negative charge regions are lower than 2km. The bipolar lightning flashes observed in this campaign neutralize positive charge after lowering the negative charge to the ground.

Negative differential mobility for negative carriers as revealed by space charge measurements on crosslinked polyethylene insulated model cables

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

Teyssedre, G., E-mail: gilbert.teyssedre@laplace.univ-tlse.fr; Laurent, C.; CNRS, LAPLACE, F-31062 Toulouse

Among features observed in polyethylene materials under relatively high field, space charge packets, consisting in a pulse of net charge that remains in the form of a pulse as it crosses the insulation, are repeatedly observed but without complete theory explaining their formation and propagation. Positive charge packets are more often reported, and the models based on negative differential mobility(NDM) for the transport of holes could account for some charge packets phenomenology. Conversely, NDM for electrons transport has never been reported so far. The present contribution reports space charge measurements by pulsed electroacoustic method on miniature cables that are modelmore » of HVDC cables. The measurements were realized at room temperature or with a temperature gradient of 10 °C through the insulation under DC fields on the order 30–60 kV/mm. Space charge results reveal systematic occurrence of a negative front of charges generated at the inner electrode that moves toward the outer electrode at the beginning of the polarization step. It is observed that the transit time of the front of negative charge increases, and therefore the mobility decreases, with the applied voltage. Further, the estimated mobility, in the range 10{sup −14}–10{sup −13} m{sup 2} V{sup −1} s{sup −1} for the present results, increases when the temperature increases for the same condition of applied voltage. The features substantiate the hypothesis of negative differential mobility used for modelling space charge packets.« less

Comparison and characterization of different tunnel layers, suitable for passivated contact formation

NASA Astrophysics Data System (ADS)

Ling, Zhi Peng; Xin, Zheng; Ke, Cangming; Jammaal Buatis, Kitz; Duttagupta, Shubham; Lee, Jae Sung; Lai, Archon; Hsu, Adam; Rostan, Johannes; Stangl, Rolf

2017-08-01

Passivated contacts for solar cells can be realized using a variety of differently formed ultra-thin tunnel oxide layers. Assessing their interface properties is important for optimization purposes. In this work, we demonstrate the ability to measure the interface defect density distribution D it(E) and the fixed interface charge density Q f for ultra-thin passivation layers operating within the tunnel regime (<2 nm). Various promising tunnel layer candidates [i.e., wet chemically formed SiO x , UV photo-oxidized SiO x , and atomic layer deposited (ALD) AlO x ] are investigated for their potential application forming electron or hole selective tunnel layer passivated contacts. In particular, ALD AlO x is identified as a promising tunnel layer candidate for hole-extracting passivated contact formation, stemming from its high (negative) fixed interface charge density in the order of -6 × 1012 cm-2. This is an order of magnitude higher compared to wet chemically or UV photo-oxidized formed silicon oxide tunnel layers, while keeping the density of interface defect states D it at a similar level (in the order of ˜2 × 1012 cm-2 eV-1). This leads to additional field effect passivation and therefore to significantly higher measured effective carrier lifetimes (˜2 orders of magnitude). A surface recombination velocity of ˜40 cm/s has been achieved for a 1.5 nm thin ALD AlO x tunnel layer prior to capping by an additional hole transport material, like p-doped poly-Si or PEDOT:PSS.

Irreversibility and higher-spin conformal field theory

NASA Astrophysics Data System (ADS)

Anselmi, Damiano

2000-08-01

I discuss the properties of the central charges c and a for higher-derivative and higher-spin theories (spin 2 included). Ordinary gravity does not admit a straightforward identification of c and a in the trace anomaly, because it is not conformal. On the other hand, higher-derivative theories can be conformal, but have negative c and a. A third possibility is to consider higher-spin conformal field theories. They are not unitary, but have a variety of interesting properties. Bosonic conformal tensors have a positive-definite action, equal to the square of a field strength, and a higher-derivative gauge invariance. There exists a conserved spin-2 current (not the canonical stress tensor) defining positive central charges c and a. I calculate the values of c and a and study the operator-product structure. Higher-spin conformal spinors have no gauge invariance, admit a standard definition of c and a and can be coupled to Abelian and non-Abelian gauge fields in a renormalizable way. At the quantum level, they contribute to the one-loop beta function with the same sign as ordinary matter, admit a conformal window and non-trivial interacting fixed points. There are composite operators of high spin and low dimension, which violate the Ferrara-Gatto-Grillo theorem. Finally, other theories, such as conformal antisymmetric tensors, exhibit more severe internal problems. This research is motivated by the idea that fundamental quantum field theories should be renormalization-group (RG) interpolations between ultraviolet and infrared conformal fixed points, and quantum irreversibility should be a general principle of nature.

Bactericidal action mechanism of negatively charged food grade clove oil nanoemulsions.

PubMed

Majeed, Hamid; Liu, Fei; Hategekimana, Joseph; Sharif, Hafiz Rizwan; Qi, Jing; Ali, Barkat; Bian, Yuan-Yuan; Ma, Jianguo; Yokoyama, Wallace; Zhong, Fang

2016-04-15

Clove oil (CO) anionic nanoemulsions were prepared with varying ratios of CO to canola oil (CA), emulsified and stabilized with purity gum ultra (PGU), a newly developed succinylated waxy maize starch. Interfacial tension measurements showed that CO acted as a co-surfactant and there was a gradual decrease in interfacial tension which favored the formation of small droplet sizes on homogenization until a critical limit (5:5% v/v CO:CA) was reached. Antimicrobial activity of the negatively charged CO nanoemulsion was determined against Gram positive GPB (Listeria monocytogenes and Staphylococcus aureus) and Gram negative GNB (Escherichia coli) bacterial strains using minimum inhibitory concentration (MIC) and a time kill dynamic method. Negatively charged PGU emulsified CO nanoemulsion showed prolonged antibacterial activities against Gram positive bacterial strains. We concluded that negatively charged CO nanoemulsion droplets self-assemble with GPB cell membrane, and facilitated interaction with cellular components of bacteria. Moreover, no electrostatic interaction existed between negatively charged droplets and the GPB membrane. Copyright © 2015 Elsevier Ltd. All rights reserved.

77 FR 1101 - Self-Regulatory Organizations; C2 Options Exchange, Incorporated; Notice of Filing and Immediate...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-09

... Login ID and FIX Login ID to $500 per month for regular access and $1000 per month for Sponsored User... a FIX fee of $1200 for a minimum of two monthly login IDs (so, $600 for one), or a fee of $2,400 for... to increase the fees charged for a CMI Login ID and FIX Login ID to $500 per month for regular access...

Biochemical Study of Anti-Inflammatory Proteins vCCI and vMIP-II

DTIC Science & Technology

2014-07-17

protein ), where we showed that vCCI is able to bind so many different chemokines due to its general negatively charged surface , allowing it to bind...sample of these competition curves. Our conclusion from the data in Table 1 and Figure 1 is that the negatively charged surface of vCCI allows it to...Similar to our mutagenesis results, the overall data indicate that vCCI uses a negatively charged surface to bind positive charges on the chemokine

Host-guest chemistry of dendrimer-drug complexes. 2. Effects of molecular properties of guests and surface functionalities of dendrimers.

PubMed

Hu, Jingjing; Cheng, Yiyun; Wu, Qinglin; Zhao, Libo; Xu, Tongwen

2009-08-06

The host-guest chemistry of dendrimer-drug complexes is investigated by NMR techniques, including (1)H NMR and 2D-NOESY studies. The effects of molecular properties of drug molecules (protonation ability and spatial steric hindrance of charged groups) and surface functionalities of dendrimers (positively charged amine groups and negatively charged carboxylate groups) on the host-guest interactions are discussed. Different interaction mechanisms between dendrimers and drug molecules are proposed on the basis of NMR results. Primary amine- and secondary amine-containing drugs preferentially bind to negatively charged dendrimers by strong electrostatic interactions, whereas tertiary amine and quaternary ammonium-containing drugs have weak binding ability with dendrimers due to relatively low protonation ability of the tertiary amine group and serious steric hindrance of the quaternary ammonium group. Positively charged drugs locate only on the surface of negatively charged dendrimers, whereas negatively charged drugs locate both on the surface and in the interior cavities of positively charged dendrimers. The host-guest chemistry of dendrimer-drug complexes is promising for the development of new drug delivery systems.

Nanotribological Properties of Positively and Negatively charged nanodiamonds as additives to solutions

NASA Astrophysics Data System (ADS)

Liu, Zijian; Corley, Steven; Shenderova, Olga; Brenner, Donald; Krim, Jacqueline

2013-03-01

Nano-diamond (ND) particles are known to be beneficial for wear and friction reduction when used as additives in liquids, but the fundamental origins of the improvement in tribological properties has not been established. In order to explore this issue, we have investigated the nanotribological properties of ND coated with self-assembled monolayers (SAM) as additives to solutions, employing gold/chrome coated quartz crystal microbalances (QCM). Measurements were performed with the QCM initially immersed in deionized water. ND particles with positively and negatively charged SAM end groups were then added to the water, while the frequency and amplitude of the QCM were monitored. Negative shifts in both the QCM frequency and amplitude were observed when ND with positively charged SAM end groups were added, while positive shifts in both the QCM frequency and amplitude were observed when ND with negatively charged ND end groups were added. The results are consistent with a lubricating effect for the negatively charged ND, but were only observed for sufficiently small negative ND particle size. Experiments on QCM surfaces with differing textures and roughness are in progress, to determine the separate contributing effects of surface roughness charge-water interactions. Funding provided by NSF DMR.

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

Johnstone, Peter; Jacobson, Arne; Mills, Evan

Creation of light for work, socializing, and general illumination is a fundamental application of technology around the world. For those who lack access to electricity, an emerging and diverse range of LED based lighting products hold promise for replacing and/or augmenting their current fuel-based lighting sources that are costly and dirty. Along with analysis of environmental factors, economic models for total cost-ofownership of LED lighting products are an important tool for studying the impacts of these products as they emerge in markets of developing countries. One important metric in those models is the minimum illuminance demanded by end-users for amore » given task before recharging the lamp or replacing batteries. It impacts the lighting service cost per unit time if charging is done with purchased electricity, batteries, or charging services. The concept is illustrated in figure 1: LED lighting products are generally brightest immediately after the battery is charged or replaced and the illuminance degrades as the battery is discharged. When a minimum threshold level of illuminance is reached, the operational time for the battery charge cycle is over. The cost to recharge depends on the method utilized; these include charging at a shop at a fixed price per charge, charging on personal grid connections, using solar chargers, and purchasing dry cell batteries. This Research Note reports on the observed"charge-triggering" illuminance level threshold for night market vendors who use LED lighting products to provide general and task oriented illumination. All the study participants charged with AC power, either at a fixed-price charge shop or with electricity at their home.« less

Impact of Rate Design Alternatives on Residential Solar Customer Bills. Increased Fixed Charges, Minimum Bills and Demand-based Rates

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

Bird, Lori; Davidson, Carolyn; McLaren, Joyce

With rapid growth in energy efficiency and distributed generation, electric utilities are anticipating stagnant or decreasing electricity sales, particularly in the residential sector. Utilities are increasingly considering alternative rates structures that are designed to recover fixed costs from residential solar photovoltaic (PV) customers with low net electricity consumption. Proposed structures have included fixed charge increases, minimum bills, and increasingly, demand rates - for net metered customers and all customers. This study examines the electricity bill implications of various residential rate alternatives for multiple locations within the United States. For the locations analyzed, the results suggest that residential PV customers offset,more » on average, between 60% and 99% of their annual load. However, roughly 65% of a typical customer's electricity demand is non-coincidental with PV generation, so the typical PV customer is generally highly reliant on the grid for pooling services.« less

Surface adsorption of oppositely charged C14TAB-PAMPS mixtures at the air/water interface and the impact on foam film stability.

PubMed

Fauser, Heiko; von Klitzing, Regine; Campbell, Richard A

2015-01-08

We have studied the oppositely charged polyelectrolyte/surfactant mixture of poly(acrylamidomethylpropanesulfonate) sodium salt (PAMPS) and tetradecyl trimethylammonium bromide (C14TAB) using a combination of neutron reflectivity and ellipsometry measurements. The interfacial composition was determined using three different analysis methods involving the two techniques for the first time. The bulk surfactant concentration was fixed at a modest value while the bulk polyelectrolyte concentration was varied over a wide range. We reveal complex changes in the surface adsorption behavior. Mixtures with low bulk PAMPS concentrations result in the components interacting synergistically in charge neutral layers at the air/water interface. At the bulk composition where PAMPS and C14TAB are mixed in an equimolar charge ratio in the bulk, we observe a dramatic drop in the surfactant surface excess to leave a large excess of polyelectrolyte at the interface, which we infer to have loops in its interfacial structure. Further increase of the bulk PAMPS concentration leads to a more pronounced depletion of material from the surface. Mixtures containing a large excess of PAMPS in the bulk showed enhanced adsorption, which is attributed to the large increase in total ionic strength of the system and screening of the surfactant headgroup charges. The data are compared to our former results on PAMPS/C14TAB mixtures [Kristen et al. J. Phys. Chem. B, 2009, 23, 7986]. A peak in the surface tension is rationalized in terms of the changing surface adsorption and, unlike in more concentrated systems, is unrelated to bulk precipitation. Also, a comparison between the determined interfacial composition with zeta potential and foam film stability data shows that the highest film stability occurs when there is enhanced synergistic adsorption of both components at the interface due to charge screening when the total ionic strength of the system is highest. The additional contribution to the foam stability of the negatively charged polyelectrolyte within the film bulk is also discussed.

76 FR 67519 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Notice of Filing of Proposed...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-01

... Expand the Applicability of the Fails Charge to Agency Debt Securities Transactions October 26, 2011... the fails charge to Agency debt securities transactions. II. Self-Regulatory Organization's Statement... Federal Reserve Bank of New York (the ``FRBNY''), has been addressing the persistent settlement fails in...

18 CFR 11.8 - Adjustment of annual charges.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Adjustment of annual charges. 11.8 Section 11.8 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION... in effect as fixed unless changed as authorized by law. [51 FR 24318, July 3, 1986] ...

18 CFR 11.8 - Adjustment of annual charges.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Adjustment of annual charges. 11.8 Section 11.8 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION... in effect as fixed unless changed as authorized by law. [51 FR 24318, July 3, 1986] ...

18 CFR 11.8 - Adjustment of annual charges.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false Adjustment of annual charges. 11.8 Section 11.8 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION... in effect as fixed unless changed as authorized by law. [51 FR 24318, July 3, 1986] ...

18 CFR 11.8 - Adjustment of annual charges.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false Adjustment of annual charges. 11.8 Section 11.8 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION... in effect as fixed unless changed as authorized by law. [51 FR 24318, July 3, 1986] ...

18 CFR 11.8 - Adjustment of annual charges.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Adjustment of annual charges. 11.8 Section 11.8 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION... in effect as fixed unless changed as authorized by law. [51 FR 24318, July 3, 1986] ...

7 CFR 1810.1 - Information concerning interest rates, amortization, guarantee fee, annual charge, and fixed period.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 12 2010-01-01 2010-01-01 false Information concerning interest rates, amortization... UTILITIES SERVICE, AND FARM SERVICE AGENCY, DEPARTMENT OF AGRICULTURE GENERAL REGULATIONS INTEREST RATES, TERMS, CONDITIONS, AND APPROVAL AUTHORITY Interest Rates, Amortization, Guarantee Fee, Annual Charge...

Comparison of oral health-related quality of life of patients treated by palatal expanders with patients treated by fixed orthodontic appliances.

PubMed

Alghamdi, Mariana A; Farsi, Nada J; Hassan, Ali H

2017-01-01

Wearing orthodontic appliances may negatively affect a patient's oral health-related quality of life (OHRQoL) physiologically, psychologically, and socially. Few studies have assessed the effect of palatal expanders on OHRQoL. The aim of this study was to evaluate the impact of palatal expanders on OHRQoL and to compare it with that of fixed orthodontic appliances. All adolescent and adult orthodontic patients who were undergoing treatment with fixed appliances or palatal expanders between July 2015 and January 2016 in King Abdulaziz University Orthodontc Dental Clinics, were recruited (n=399). The OHRQoL of each participant was assessed using the shortened Arabic version of the Oral Health Impact Profile-14 questionnaire. OHRQoL was compared between users of fixed appliances and users of palatal expanders; it was also compared after stratifying the patients by gender. Chi-squared and Fisher's exact tests were used, as indicated. Palatal expanders had significantly greater negative effects on chewing ability ( P ≤0.01) and pronunciation ( P =0.048). However, fixed orthodontic appliances had significantly greater negative impacts on mouth aching ( P =0.003), difficulty in relaxing ( P =0.01), irritability ( P =0.001), and embarrassment ( P ≤0.01). Palatal expanders had a significantly greater negative impact on some aspects of OHRQoL when compared with fixed orthodontic appliances in adolescents and young adults.

Electrostatic, elastic and hydration-dependent interactions in dermis influencing volume exclusion and macromolecular transport.

PubMed

Øien, Alf H; Wiig, Helge

2016-07-07

Interstitial exclusion refers to the limitation of space available for plasma proteins and other macromolecules based on collagen and negatively charged glycosaminoglycans (GAGs) in the interstitial space. It is of particular importance to interstitial fluid and plasma volume regulation. Here we present a novel mechanical and mathematical model of the dynamic interactions of structural elements within the interstitium of the dermis at the microscopic level that may explain volume exclusion of charged and neutral macroparticles. At this level, the interstitium is considered to consist of elements called extracellular matrix (ECM) cells, again containing two main interacting structural components on a fluid background including anions and cations setting up osmotic forces: one smaller GAG component, having an intrinsic expansive electric force, and one bigger collagen component, having an intrinsic elastic force. Because of size differences, the GAG component interacts with a fraction of the collagen component only at normal hydration. This fraction, however, increases with rising hydration as a consequence of the modeled form of the interaction force between the GAGs and collagen. Collagen is locally displaced at variable degrees as hydration changes. Two models of GAGs are considered, having largely different geometries which demands different, but related, forms of GAG-collagen interaction forces. The effects of variable fixed charges on GAGs and of GAG density in tissue are evaluated taking into account observed volume exclusion properties of charged macromolecules as a function of tissue hydration. The presented models may improve our biophysical understanding of acting forces influencing tissue fluid dynamics. Such knowledge is significant when evaluating the transport of electrically charged and neutral macromolecules into and through the interstitium, and therefore to drug uptake and the therapeutic effects of macromolecular agents. Copyright © 2016 Elsevier Ltd. All rights reserved.

Charge-regularized swelling kinetics of polyelectrolyte gels: Elasticity and diffusion

NASA Astrophysics Data System (ADS)

Sen, Swati; Kundagrami, Arindam

2017-11-01

We apply a recently developed method [S. Sen and A. Kundagrami, J. Chem. Phys. 143, 224904 (2015)], using a phenomenological expression of osmotic stress, as a function of polymer and charge densities, hydrophobicity, and network elasticity for the swelling of spherical polyelectrolyte (PE) gels with fixed and variable charges in a salt-free solvent. This expression of stress is used in the equation of motion of swelling kinetics of spherical PE gels to numerically calculate the spatial profiles for the polymer and free ion densities at different time steps and the time evolution of the size of the gel. We compare the profiles of the same variables obtained from the classical linear theory of elasticity and quantitatively estimate the bulk modulus of the PE gel. Further, we obtain an analytical expression of the elastic modulus from the linearized expression of stress (in the small deformation limit). We find that the estimated bulk modulus of the PE gel decreases with the increase of its effective charge for a fixed degree of deformation during swelling. Finally, we match the gel-front locations with the experimental data, taken from the measurements of charged reversible addition-fragmentation chain transfer gels to show an increase in gel-size with charge and also match the same for PNIPAM (uncharged) and imidazolium-based (charged) minigels, which specifically confirms the decrease of the gel modulus value with the increase of the charge. The agreement between experimental and theoretical results confirms general diffusive behaviour for swelling of PE gels with a decreasing bulk modulus with increasing degree of ionization (charge). The new formalism captures large deformations as well with a significant variation of charge content of the gel. It is found that PE gels with large deformation but same initial size swell faster with a higher charge.

Electrophoresis of a charged soft particle in a charged cavity with arbitrary double-layer thickness.

PubMed

Chen, Wei J; Keh, Huan J

2013-08-22

An analysis for the quasi-steady electrophoretic motion of a soft particle composed of a charged spherical rigid core and an adsorbed porous layer positioned at the center of a charged spherical cavity filled with an arbitrary electrolyte solution is presented. Within the porous layer, frictional segments with fixed charges are assumed to distribute uniformly. Through the use of the linearized Poisson-Boltzmann equation and the Laplace equation, the equilibrium double-layer potential distribution and its perturbation caused by the applied electric field are separately determined. The modified Stokes and Brinkman equations governing the fluid flow fields outside and inside the porous layer, respectively, are solved subsequently. An explicit formula for the electrokinetic migration velocity of the soft particle in terms of the fixed charge densities on the rigid core surface, in the porous layer, and on the cavity wall is obtained from a balance between its electrostatic and hydrodynamic forces. This formula is valid for arbitrary values of κa, λa, r0/a, and a/b, where κ is the Debye screening parameter, λ is the reciprocal of the length characterizing the extent of flow penetration inside the porous layer, a is the radius of the soft particle, r0 is the radius of the rigid core of the particle, and b is the radius of the cavity. In the limiting cases of r0 = a and r0 = 0, the migration velocity for the charged soft sphere reduces to that for a charged impermeable sphere and that for a charged porous sphere, respectively, in the charged cavity. The effect of the surface charge at the cavity wall on the particle migration can be significant, and the particle may reverse the direction of its migration.

How to Estimate Demand Charge Savings from PV on Commercial Buildings

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

Gagnon, Pieter J; Bird, Lori A

Rooftop photovoltaic (PV) systems are compensated through retail electricity tariffs - and for commercial and industrial customers, these are typically comprised of three components: a fixed monthly charge, energy charges, and demand charges. Of these, PV's ability to reduce demand charges has traditionally been the most difficult to estimate. In this fact sheet we explain the basics of demand charges, and provide a new method that a potential customer or PV developer can use to estimate a range of potential demand charge savings for a proposed PV system. These savings can then be added to other project cash flows, inmore » assessing the project's financial performance.« less

Aberration of a negative ion beam caused by space charge effect.

PubMed

Miyamoto, K; Wada, S; Hatayama, A

2010-02-01

Aberrations are inevitable when the charged particle beams are extracted, accelerated, transmitted, and focused with electrostatic and magnetic fields. In this study, we investigate the aberration of a negative ion accelerator for a neutral beam injector theoretically, especially the spherical aberration caused by the negative ion beam expansion due to the space charge effect. The negative ion current density profiles with the spherical aberration are compared with those without the spherical aberration. It is found that the negative ion current density profiles in a log scale are tailed due to the spherical aberration.

Recombination energy for negatively charged excitons inside type-II core/shell spherical quantum dots

NASA Astrophysics Data System (ADS)

Chafai, A.; Essaoudi, I.; Ainane, A.; Dujardin, F.; Ahuja, R.

2018-07-01

The recombination energy of isolated neutral exciton and that of isolated negatively charged exciton inside a type-II core/shell spherical quantum dot are studied. Our investigation considers the charge-carriers effective mass discontinuity at the surface contact between the core and shell materials. Although our model omits the effect of the surface polarization, the dielectric-constant mismatch at the nanodot boundaries was taken into account. In order to achieve the exciton and negative trion energies, we proceed by a variational calculation in the framework of the envelope approximation. Our results reveal a strong correlation between the nanodot morphology and the energy spectrum of the neutral and negatively charged exciton.

Primary energy reconstruction from the charged particle densities recorded at 500 m distance from shower core with the KASCADE-Grande detector

NASA Astrophysics Data System (ADS)

Toma, G.; Apel, W. D.; Arteaga, J. C.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brâncuş, I. M.; Buchholz, P.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Finger, M.; Fuhrmann, D.; Ghia, P. L.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Kickelbick, D.; Klages, H. O.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Mayer, H. J.; Melissas, M.; Milke, J.; Mitrică, B.; Morello, C.; Navarra, G.; Nehls, S.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Palmieri, N.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schröder, F. G.; Sima, O.; Trinchero, G. C.; Ulrich, H.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.

2011-05-01

Previous EAS investigations have shown that for a fixed primary energy the charged particle density becomes independent of the primary mass at certain (fixed) distances from the shower axis. This feature can be used as an estimator for the primary energy. We present results on the reconstruction of the primary energy spectrum of cosmic rays from the experimentally recorded S(500) observable (the density of charged particles at a distance of 500 m to the shower core as measured in a plane normal to the shower axis) using the KASCADE-Grande detector array. The KASCADE-Grande experiment is hosted by the Karlsruhe Institute for Technology - Campus North, Karlsruhe, Germany, 110 m a.s.l. and operated by an international collaboration. The obtained primary energy spectrum is presented along with the result of another reconstruction technique presently employed at KASCADE-Grande.

Electron teleportation and statistical transmutation in multiterminal Majorana islands

NASA Astrophysics Data System (ADS)

Michaeli, Karen; Landau, L. Aviad; Sela, Eran; Fu, Liang

2017-11-01

We study a topological superconductor island with spatially separated Majorana modes coupled to multiple normal-metal leads by single-electron tunneling in the Coulomb blockade regime. We show that low-temperature transport in such a Majorana island is carried by an emergent charge-e boson composed of a Majorana mode and an electronic excitation in leads. This transmutation from Fermi to Bose statistics has remarkable consequences. For noninteracting leads, the system flows to a non-Fermi-liquid fixed point, which is stable against tunnel couplings anisotropy or detuning away from the charge-degeneracy point. As a result, the system exhibits a universal conductance at zero temperature, which is a fraction of the conductance quantum, and low-temperature corrections with a universal power-law exponent. In addition, we consider Majorana islands connected to interacting one-dimensional leads, and find different stable fixed points near and far from the charge-degeneracy point.

"Squishy capacitor" model for electrical double layers and the stability of charged interfaces.

PubMed

Partenskii, Michael B; Jordan, Peter C

2009-07-01

Negative capacitance (NC), predicted by various electrical double layer (EDL) theories, is critically reviewed. Physically possible for individual components of the EDL, the compact or diffuse layer, it is strictly prohibited for the whole EDL or for an electrochemical cell with two electrodes. However, NC is allowed for the artificial conditions of sigma control, where an EDL is described by the equilibrium electric response of electrolyte to a field of fixed, and typically uniform, surface charge-density distributions, sigma. The contradiction is only apparent; in fact local sigma cannot be set independently, but is established by the equilibrium response to physically controllable variables, i.e., applied voltage phi (phi control) or total surface charge q (q control). NC predictions in studies based on sigma control signify potential instabilities and phase transitions for physically realizable conditions. Building on our previous study of phi control [M. B. Partenskii and P. C. Jordan, Phys. Rev. E 77, 061117 (2008)], here we analyze critical behavior under q control, clarifying the basic picture using an exactly solvable "squishy capacitor" toy model. We find that phi can change discontinuously in the presence of a lateral transition, specify stability conditions for an electrochemical cell, analyze the origin of the EDL's critical point in terms of compact and diffuse serial contributions, and discuss perspectives and challenges for theoretical studies not limited by sigma control.

Controlling Two-dimensional Tethered Vesicle Motion Using an Electric Field

PubMed Central

Yoshina-Ishii, Chiaki; Boxer, Steven G.

2008-01-01

We recently introduced methods to tether phospholipid vesicles or proteoliposomes onto a fluid supported lipid bilayer using DNA hybridization. These intact tethered vesicles diffuse in two dimensions parallel to the supporting membrane surface. In this paper, we report the dynamic response of individual tethered vesicles to an electric field applied parallel to the bilayer surface. Vesicles respond to the field by moving in the direction of electro-osmotic flow, and this can be used to reversibly concentrate tethered vesicles against a barrier. By adding increasing amounts of negatively charged phosphatidylserine to the supporting bilayer to increase electro-osmosis, the electrophoretic mobility of the tethered vesicles can be increased. The electro-osmotic contribution can be modeled well by a sphere connected to a cylindrical anchor in a viscous membrane with charged head groups. The electrophoretic force on the negatively charged tethered vesicles opposes the electro-osmotic force. By increasing the amount of negative charge on the tethered vesicle, drift in the direction of electro-osmotic flow can be slowed; at high negative charge on the tethered vesicle, motion can be forced in the direction of electrophoresis. The balance between these forces can be visualized on a patterned supporting bilayer containing negatively charged lipids which themselves reorganize in an externally applied electric field to create a gradient of charge within a corralled region. The charge gradient at the surface creates a gradient of electro-osmotic flow, and vesicles carrying similar amounts of negative charge can be focused to a region perpendicular to the applied field where electrophoresis is balanced by electro-osmosis, away from the corral boundary. Electric fields are effective tools to direct tethered vesicles, concentrate them and to measure the tethered vesicle’s electrostatic properties. PMID:16489833

Gas-Phase Stability of Negatively Charged Organophosphate Metabolites Produced by Electrospray Ionization and Matrix-Assisted Laser Desorption/Ionization

NASA Astrophysics Data System (ADS)

Asakawa, Daiki; Mizuno, Hajime; Toyo'oka, Toshimasa

2017-12-01

The formation mechanisms of singly and multiply charged organophosphate metabolites by electrospray ionization (ESI) and their gas phase stabilities were investigated. Metabolites containing multiple phosphate groups, such as adenosine 5'-diphosphate (ADP), adenosine 5'-triphosphate (ATP), and D- myo-inositol-1,4,5-triphosphate (IP3) were observed as doubly deprotonated ions by negative-ion ESI mass spectrometry. Organophosphates with multiple negative charges were found to be unstable and often underwent loss of PO3 -, although singly deprotonated analytes were stable. The presence of fragments due to the loss of PO3 - in the negative-ion ESI mass spectra could result in the misinterpretation of analytical results. In contrast to ESI, matrix-assisted laser desorption ionization (MALDI) produced singly charged organophosphate metabolites with no associated fragmentation, since the singly charged anions are stable. The stability of an organophosphate metabolite in the gas phase strongly depends on its charge state. The fragmentations of multiply charged organophosphates were also investigated in detail through density functional theory calculations. [Figure not available: see fulltext.

Charge mobility retrieval approach from apparent charge packet movements based on the negative differential resistance theory.

PubMed

Meng, Jia; Zhang, Yewen; Holé, Stéphane; Zheng, Feihu; An, Zhenlian

2018-04-12

Space charge migration characteristics play an important role in the evaluation of polymer insulation performance. However, an accurate description of charge carrier mobility in several typical insulating polymers such as polyethylene, polypropylene is currently not available. Recently, with the observation of a series of negative charge packet movements associated with the negative differential resistance characteristic of charge mobility in LDPE films, the extraction of charge mobility from the apparent charge packet movement has been attempted using appropriate methods. Based on the previous report of the successful derivation of charge mobility from experimental results using numerical methods, the present research improves the derivation accuracy and describes the details of the charge mobility derivation procedure. Back simulation results under several typical polarizing fields using the derived charge mobility are exhibited. The results indicate that both the NDR theory and the simulation models for the polyethylene materials are reasonable. A significant migration velocity difference between the charge carrier and the charge packet is observed. Back simulations of the charge packet under several typical polarizing fields using the obtained E-v curve show good agreement with the experimental results. The charge packet shapes during the migrations were also found to vary with the polarizing field.

ESI-MS of Cucurbituril Complexes Under Negative Polarity.

PubMed

Rodrigues, Maria A A; Mendes, Débora C; Ramamurthy, Vaidhyanathan; Da Silva, José P

2017-11-01

Electrospray ionization mass spectrometry (ESI-MS) is a powerful tool to study host-guest supramolecular interactions. ESI-MS can be used for detailed gas-phase reactivity studies, to clarify the structure, or simply to verify the formation of complexes. Depending on the structure of the host and of the guest, negative and/or positive ESI are used. Here we report the unexpected formation of host-guest complexes between cucurbit[n]urils (n = 7, 8, CB[n]) and amine, styryl pyridine, and styryl pyridine dimer cations, under negative ESI. Non-complexed CB[n] form double charged halide (Br - , Cl - , F - ) adducts. Under negative ESI, halide ions interact with CB[n] outer surface hydrogen atoms. One to one host-guest complexes (1:1) of CB[n] with positive charged guests were also observed as single and double charged ions under negative ESI. The positive charge of guests is neutralized by ion-pairing with halide anions. Depending on the number of positive charges guests retain in the gas phase, one or two additional halide ions are required for neutralization. Complexes 1:2 of CB[8] with styryl pyridines retain two halide ions in the gas phase, one per guest. Styryl pyridine dimers form 1:1 complexes possessing a single extra halide ion and therefore a single positive charge. Negative ESI is sensitive to small structural differences between complexes, distinguishing between 1:2 complexes of styryl pyridine-CB[8] and corresponding 1:1 complexes with the dimer. Negative ESI gives simpler spectra than positive ESI and allows the determination of guest charge state of CB[n] complexes in the gas phase. Graphical Abstract ᅟ.

Oblique Interaction of Dust-ion Acoustic Solitons with Superthermal Electrons in a Magnetized Plasma

NASA Astrophysics Data System (ADS)

Parveen, Shahida; Mahmood, Shahzad; Adnan, Muhammad; Qamar, Anisa

2018-01-01

The oblique interaction between two dust-ion acoustic (DIA) solitons travelling in the opposite direction, in a collisionless magnetized plasma composed of dynamic ions, static dust (positive/negative) charged particles and interialess kappa distributed electrons is investigated. By employing extended Poincaré-Lighthill-Kuo (PLK) method, Korteweg-de Vries (KdV) equations are derived for the right and left moving low amplitude DIA solitons. Their trajectories and corresponding phase shifts before and after their interaction are also obtained. It is found that in negatively charged dusty plasma above the critical dust charged to ion density ratio the positive polarity pulse is formed, while below the critical dust charged density ratio the negative polarity pulse of DIA soliton exist. However it is found that only positive polarity pulse of DIA solitons exist for the positively charged dust particles case in a magnetized nonthermal plasma. The nonlinearity coefficient in the KdV equation vanishes for the negatively charged dusty plasma case for a particular set of parameters. Therefore, at critical plasma density composition for negatively charged dust particles case, the modified Korteweg-de Vries (mKdV) equations having cubic nonlinearity coefficient of the DIA solitons, and their corresponding phase shifts are derived for the left and right moving solitons. The effects of the system parameters including the obliqueness of solitons propagation with respect to magnetic field direction, superthermality of electrons and concentration of positively/negatively static dust charged particles on the phase shifts of the colliding solitons are also discussed and presented numerically. The results are applicable to space magnetized dusty plasma regimes.

Adhesion of osteoblasts to a nanorough titanium implant surface

PubMed Central

Gongadze, Ekaterina; Kabaso, Doron; Bauer, Sebastian; Slivnik, Tomaž; Schmuki, Patrik; van Rienen, Ursula; Iglič, Aleš

2011-01-01

This work considers the adhesion of cells to a nanorough titanium implant surface with sharp edges. The basic assumption was that the attraction between the negatively charged titanium surface and a negatively charged osteoblast is mediated by charged proteins with a distinctive quadrupolar internal charge distribution. Similarly, cation-mediated attraction between fibronectin molecules and the titanium surface is expected to be more efficient for a high surface charge density, resulting in facilitated integrin mediated osteoblast adhesion. We suggest that osteoblasts are most strongly bound along the sharp convex edges or spikes of nanorough titanium surfaces where the magnitude of the negative surface charge density is the highest. It is therefore plausible that nanorough regions of titanium surfaces with sharp edges and spikes promote the adhesion of osteoblasts. PMID:21931478

47 CFR 1.1107 - Schedule of charges for applications and other filings for the international services.

Code of Federal Regulations, 2010 CFR

2010-10-01

.... Assignments or transfers (all services) Corres & 159 1,015.00 CUT 3. Fixed Satellite Transmit/Receive Earth... 175.00 CGX 4. Fixed Satellite transmit/receive Earth Stations (2 meters or less operating in the 4/6... Only Earth Stations: a. Initial Applications for Registration or License (per station) 312 Main...

33 CFR 67.40-20 - Charges invoiced to owner.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Charges invoiced to owner. 67.40-20 Section 67.40-20 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Notification § 67.40-20...

33 CFR 67.40-20 - Charges invoiced to owner.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Charges invoiced to owner. 67.40-20 Section 67.40-20 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Notification § 67.40-20...

Kinetics of electrically and chemically induced swelling in polyelectrolyte gels

NASA Astrophysics Data System (ADS)

Grimshaw, P. E.; Nussbaum, J. H.; Grodzinsky, A. J.; Yarmush, M. L.

1990-09-01

Controlled swelling and shrinking of polyelectrolyte gels is useful for regulating the transport of solutes into, out of, and through these materials. A macroscopic continuum model is presented to predict the kinetics of swelling in polyelectrolyte gel membranes induced by augmentation of electrostatic swelling forces arising from membrane fixed charge groups. The model accounts for ionic transport within the membrane, electrodiffusion phenomena, dissociation of membrane charge groups, intramembrane fluid flow, and mechanical deformation of the membrane matrix. Model predictions are compared with measurements of chemically and electrically induced swelling and shrinking in crosslinked polymethacrylic acid (PMAA) membranes. Large, reversible changes in PMAA membrane hydration were observed after changing the bath pH or by applying an electric field to modify the intramembrane ionic environment and fixed charge density. A relatively slow swelling process and more rapid shrinking for both chemical and electrical modulation of the intramembrane pH are observed. The model indicates that retardation of membrane swelling is dominated by diffusion-limited reaction of H+ ions with membrane charge groups, and that the more rapid shrinking is limited primarily by mechanical processes.

Pulsed field sample neutralization

DOEpatents

Appelhans, Anthony D.; Dahl, David A.; Delmore, James E.

1990-01-01

An apparatus and method for alternating voltage and for varying the rate of extraction during the extraction of secondary particles, resulting in periods when either positive ions, or negative ions and electrons are extracted at varying rates. Using voltage with alternating charge during successive periods to extract particles from materials which accumulate charge opposite that being extracted causes accumulation of surface charge of opposite sign. Charge accumulation can then be adjusted to a ratio which maintains a balance of positive and negative charge emission, thus maintaining the charge neutrality of the sample.

Mobile charge, soft breakdown, and self-healing in hydrogen silsesquioxane based intermetal dielectric

NASA Astrophysics Data System (ADS)

Devine, R. A. B.

2002-09-01

The electrical characteristics of hydrogen silsesquioxane based flowable oxide (FOxregistered) films proposed for interconnect isolation applications have been studied. It is demonstrated that negative and positive charges exist in the as-made, cured films with densities of 0.95 x1012 and 1.5 x1012 cm-2, respectively for thicknesses of 114 nm. The negative charges can be removed from the films by application of modest electric fields (positive or negative, approx1.75 MV cm-1). The positive charge can be similarly displaced but not removed from the film; this results in time dependent relaxation and redistribution of the positive charge if the films are left unbiased. Time dependent irreversible evolution of the leakage current under positive and negative bias (approx3 MV cm-1) shows a slow breakdown phenomena. An unusual self-healing effect is evidenced in these films.

The Role of Hydrophobicity in the Cellular Uptake of Negatively Charged Macromolecules.

PubMed

Abou Matar, Tamara; Karam, Pierre

2018-02-01

It is generally accepted that positively charged molecules are the gold standard to by-pass the negatively charged cell membrane. Here, it is shown that cellular uptake is also possible for polymers with negatively charged side chains and hydrophobic backbones. Specifically, poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene], a conjugated polyelectrolyte with sulfonate, as water-soluble functional groups, is shown to accumulate in the intracellular region. When the polymer hydrophobic backbone is dissolved using polyvinylpyrrolidone, an amphiphilic macromolecule, the cellular uptake is dramatically reduced. The report sheds light on the fine balance between negatively charged side groups and the hydrophobicity of polymers to either enhance or reduce cellular uptake. As a result, these findings will have important ramifications on the future design of targeted cellular delivery nanocarriers for imaging and therapeutic applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stabilized thallium bromide radiation detectors and methods of making the same

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

Leao, Cedric Rocha; Lordi, Vincenzo

According to one embodiment, a crystal includes thallium bromide (TlBr), one or more positively charged dopants, and one or more negatively charged dopants. According to another embodiment, a system includes a monolithic crystal including thallium bromide (TlBr), one or more positively charged dopants, and one or more negatively charged dopants; and a detector configured to detect a signal response of the crystal.

Influence of liposome charge on the association of liposomes with Kupffer cells in vitro. Effects of divalent cations and competition with latex particles.

PubMed

Dijkstra, J; van Galen, M; Scherphof, G

1985-03-14

We studied the interaction of large unilamellar liposomes carrying different surface charges with rat Kupffer cells in maintenance culture. In addition to 14C-labeled phosphatidylcholine, all liposome preparations contained either 3H-labeled inulin or 125I-labeled bovine serum albumin as a non-degradable or a degradable aqueous space marker, respectively. With vesicles carrying no net charge, intracellular processing of internalized liposomes caused nearly complete release of protein label into the medium in acid-soluble form, while phospholipid label was predominantly retained by the cells, only about one third being released. The presence of the lysosomotropic agent, ammonia, inhibited the release of both labels from the cells. At 4 degrees C, the association and degradation of the vesicles were strongly reduced. These results are very similar to what we reported on negatively charged liposomes (Dijkstra, J., Van Galen, W.J.M., Hulstaert, C.E., Kalicharan, D., Roerdink, F.H. and Scherphof, G.L. (1984) Exp. Cell Res. 150, 161-176). The interaction of both types of vesicles apparently proceeds by adsorption to the cell surface followed by virtually complete internalization by endocytosis. Similar experiments with positively charged vesicles indicated that only about half of the liposomes were taken up by the endocytic route, the other half remaining adsorbed to the cell-surface. Attachment of all types of liposomes to the cells was strongly dependent on the presence of divalent cations; Ca2+ appeared to be required for optimal binding. Neutral liposomes only slightly competed with the uptake of negatively charged vesicles, both at 4 degrees and 37 degrees C, whereas negatively charged small unilamellar vesicles and negatively charged latex beads were found to compete very effectively with the large negatively charged liposomes. Neutral vesicles competed effectively for uptake with positively charged ones. These results suggest that neutral and positively charged liposomes are largely bound by the same cell-surface binding sites, while negatively charged vesicles attach mainly to other binding sites.

Formation of stable inverse sheath in ion–ion plasma by strong negative ion emission

NASA Astrophysics Data System (ADS)

Zhang, Zhe; Wu, Bang; Yang, Shali; Zhang, Ya; Chen, Dezhi; Fan, Mingwu; Jiang, Wei

2018-06-01

The effect of strong charged particle emission on plasma–wall interactions is a classical, yet unresolved question in plasma physics. Previous studies on secondary electron emission have shown that with different emission coefficients, there are classical, space-charge-limited, and inverse sheaths. In this letter, we demonstrate that a stable ion–ion inverse sheath and ion–ion plasma are formed with strong surface emission of negative ions. The continuous space-charge-limited to inverse ion–ion sheath transition is observed, and the plasma near the surface consequently transforms into pure ion–ion plasma. The results may explain the long-puzzled experimental observation that the density of negative ions depends on only charge not mass in negative ion sources.

Electrostatic plasma lens for focusing negatively charged particle beams.

PubMed

Goncharov, A A; Dobrovolskiy, A M; Dunets, S M; Litovko, I V; Gushenets, V I; Oks, E M

2012-02-01

We describe the current status of ongoing research and development of the electrostatic plasma lens for focusing and manipulating intense negatively charged particle beams, electrons, and negative ions. The physical principle of this kind of plasma lens is based on magnetic isolation electrons providing creation of a dynamical positive space charge cloud in shortly restricted volume propagating beam. Here, the new results of experimental investigations and computer simulations of wide-aperture, intense electron beam focusing by plasma lens with positive space charge cloud produced due to the cylindrical anode layer accelerator creating a positive ion stream towards an axis system is presented.

Comparison of oral health-related quality of life of patients treated by palatal expanders with patients treated by fixed orthodontic appliances

PubMed Central

Alghamdi, Mariana A; Farsi, Nada J; Hassan, Ali H

2017-01-01

Introduction and purpose Wearing orthodontic appliances may negatively affect a patient’s oral health-related quality of life (OHRQoL) physiologically, psychologically, and socially. Few studies have assessed the effect of palatal expanders on OHRQoL. The aim of this study was to evaluate the impact of palatal expanders on OHRQoL and to compare it with that of fixed orthodontic appliances. Materials and methods All adolescent and adult orthodontic patients who were undergoing treatment with fixed appliances or palatal expanders between July 2015 and January 2016 in King Abdulaziz University Orthodontc Dental Clinics, were recruited (n=399). The OHRQoL of each participant was assessed using the shortened Arabic version of the Oral Health Impact Profile-14 questionnaire. OHRQoL was compared between users of fixed appliances and users of palatal expanders; it was also compared after stratifying the patients by gender. Chi-squared and Fisher’s exact tests were used, as indicated. Results Palatal expanders had significantly greater negative effects on chewing ability (P≤0.01) and pronunciation (P=0.048). However, fixed orthodontic appliances had significantly greater negative impacts on mouth aching (P=0.003), difficulty in relaxing (P=0.01), irritability (P=0.001), and embarrassment (P≤0.01). Conclusion Palatal expanders had a significantly greater negative impact on some aspects of OHRQoL when compared with fixed orthodontic appliances in adolescents and young adults. PMID:28408807

Enhanced photoelectrochemical water splitting performance of anodic TiO(2) nanotube arrays by surface passivation.

PubMed

Gui, Qunfang; Xu, Zhen; Zhang, Haifeng; Cheng, Chuanwei; Zhu, Xufei; Yin, Min; Song, Ye; Lu, Linfeng; Chen, Xiaoyuan; Li, Dongdong

2014-10-08

One-dimensional anodic titanium oxide nanotube (TONT) arrays provide a direct pathway for charge transport, and thus hold great potential as working electrodes for electrochemical energy conversion and storage devices. However, the prominent surface recombination due to the large amount surface defects hinders the performance improvement. In this work, the surface states of TONTs were passivated by conformal coating of high-quality Al2O3 onto the tubular structures using atomic layer deposition (ALD). The modified TONT films were subsequently employed as anodes for photoelectrochemical (PEC) water splitting. The photocurrent (0.5 V vs Ag/AgCl) recorded under air mass 1.5 global illumination presented 0.8 times enhancement on the electrode with passivation coating. The reduction of surface recombination rate is responsible for the substantially improved performance, which is proposed to have originated from a decreased interface defect density in combination with a field-effect passivation induced by a negative fixed charge in the Al2O3 shells. These results not only provide a physical insight into the passivation effect, but also can be utilized as a guideline to design other energy conversion devices.

The influence of space charge shielding on dielectric multipactor

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

Chang, C.; Liu, G. Z.; Tang, C. X.

2009-05-15

A model of space charge influenced by multipactor electrons and plasma has been established. The positive space charge potential/field for vacuum dielectric multipactor is analytically studied. After considering the plasma, the positive space charge field is further shielded, and multipactor saturates at higher surface accumulated field, compared with that for only considering multipactor electrons. The negative space charge potential/field for dielectric breakdown at high pressure is analyzed. It is found that the negative potential can be nonmonotonously varied, forming a minimum potential well.

Physico-chemical studies on the interaction of dendrimers with lipid bilayers. 1. Effect of dendrimer generation and liposome surface charge.

PubMed

Roy, Biplab; Panda, Amiya Kumar; Parimi, Srinivas; Ametov, Igor; Barnes, Timothy; Prestidge, Clive A

2014-01-01

Studies on the interaction of different generation poly (amido amine) (PAMAM) dendrimers (2G, 4G and 6G) and liposomes of different compositions were carried out by a combined turbidity, dynamic light scattering and atomic force microscopic measurements. Liposomes comprising soy lecithin (SLC, negative surface charge), 1, 2-palmitoyl-sn-glycero-3-phosphatidylcholine (DPPC, mildly positive surface charge), 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol (DPPG, negatively charged) and a biologically simulated mixture of DPPC + DPPG (7:3, M/M, negatively charged) were used as model bilayers. 30 wt% cholesterol was used in each combination as it is known to control the fluidity of membrane bilayers. Silica was used as a negatively charged hard sphere model with an aim to compare the results. Both the turbidity and hydrodynamic diameter values of all the liposomes, except DPPC, passed through maxima upon the progressive addition of PAMAM; the effect was insignificant in case of DPPC. Formation of dendriosome, a complex formed between dendrimer and liposome, resulted in the charge reversal of the negatively charged liposomes. Interaction between PAMAM and liposome was found to be governed by electrostatic as well as hydrogen bonding. Generation dependent PAMAM activity followed the order: 6G >4G>2G in terms of overall dendrimer concentration. However, interestingly, the order was reverse when PAMAM activity was considered in terms of total end group concentrations. AFM studies reveal the rupture of bilayer structure upon addition of dendrimer.

Cost accounting in a surgical unit in a teaching hospital--a pilot study.

PubMed

Malalasekera, A P; Ariyaratne, M H; Fernando, R; Perera, D; Deen, K I

2003-09-01

Economic constraints remain one of the major limitations on the quality of health care even in industrialised countries. Improvement of quality will require optimising facilities within available resources. Our objective was to determine costs of surgery and to identify areas where cost reduction is possible. 80 patients undergoing routine major and intermediate surgery during a period of 6 months were selected at random. All consumables used and procedures carried out were documented. A unit cost was assigned to each of these. Costing was based on 3 main categories: preoperative (investigations, blood product related costs), operative (anaesthetic charges, consumables and theatre charges) and post-operative (investigations, consumables, hospital stay). Theatre charges included two components: fixed (consumables) and variable (dependent on time per operation). The indirect costs (e.g. administration costs, 'hotel' costs), accounted for 30%, of the total and were lower than similar costs in industrialised nations. The largest contributory factors (median, range) towards total cost were, basic hospital charges (30%; 15 to 63%); theatre charges fixed (23%; 6 to 35%) and variable (14%; 8 to 27%); and anaesthetic charges (15%; 1 to 36%). Cost reduction in patients undergoing surgery should focus on decreasing hospital stay, operating theatre time and anaesthetic expenditure. Although definite measures can be suggested from the study, further studies on these variables are necessary to optimise cost effectiveness of surgical units.

PHEPS: web-based pH-dependent Protein Electrostatics Server

PubMed Central

Kantardjiev, Alexander A.; Atanasov, Boris P.

2006-01-01

PHEPS (pH-dependent Protein Electrostatics Server) is a web service for fast prediction and experiment planning support, as well as for correlation and analysis of experimentally obtained results, reflecting charge-dependent phenomena in globular proteins. Its implementation is based on long-term experience (PHEI package) and the need to explain measured physicochemical characteristics at the level of protein atomic structure. The approach is semi-empirical and based on a mean field scheme for description and evaluation of global and local pH-dependent electrostatic properties: protein proton binding; ionic sites proton population; free energy electrostatic term; ionic groups proton affinities (pKa,i) and their Coulomb interaction with whole charge multipole; electrostatic potential of whole molecule at fixed pH and pH-dependent local electrostatic potentials at user-defined set of points. The speed of calculation is based on fast determination of distance-dependent pair charge-charge interactions as empirical three exponential function that covers charge–charge, charge–dipole and dipole–dipole contributions. After atomic coordinates input, all standard parameters are used as defaults to facilitate non-experienced users. Special attention was given to interactive addition of non-polypeptide charges, extra ionizable groups with intrinsic pKas or fixed ions. The output information is given as plain-text, readable by ‘RasMol’, ‘Origin’ and the like. The PHEPS server is accessible at . PMID:16845042

Beam efflux measurements

NASA Technical Reports Server (NTRS)

Komatsu, G. K.; Stellen, J. M., Jr.

1976-01-01

Measurements have been made of the high energy thrust ions, (Group I), high angle/high energy ions (Group II), and high angle/low energy ions (Group IV) of a mercury electron bombardment thruster in the angular divergence range from 0 deg to greater than 90 deg. The measurements have been made as a function of thrust ion current, propellant utilization efficiency, bombardment discharge voltage, screen and accelerator grid potential (accel-decel ratio) and neutralizer keeper potential. The shape of the Group IV (charge exchange) ion plume has remained essentially fixed within the range of variation of the engine operation parameters. The magnitude of the charge exchange ion flux scales with thrust ion current, for good propellant utilization conditions. For fixed thrust ion current, charge exchange ion flux increases for diminishing propellant utilization efficiency. Facility effects influence experimental accuracies within the range of propellant utilization efficiency used in the experiments. The flux of high angle/high energy Group II ions is significantly diminished by the use of minimum decel voltages on the accelerator grid. A computer model of charge exchange ion production and motion has been developed. The program allows computation of charge exchange ion volume production rate, total production rate, and charge exchange ion trajectories for "genuine" and "facilities effects" particles. In the computed flux deposition patterns, the Group I and Group IV ion plumes exhibit a counter motion.

Capacitive charge storage at an electrified interface investigated via direct first-principles simulations [Direct Simulation of Capacitive Charging of Graphene and Implications for Supercapacitor Design

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

Radin, Maxwell D.; Ogitsu, Tadashi; Biener, Juergen

Understanding the impact of interfacial electric fields on electronic structure is crucial to improving the performance of materials in applications based on charged interfaces. Supercapacitors store energy directly in the strong interfacial field between a solid electrode and a liquid electrolyte; however, the complex interplay between the two is often poorly understood, particularly for emerging low-dimensional electrode materials that possess unconventional electronic structure. Typical descriptions tend to neglect the specific electrode-electrolyte interaction, approximating the intrinsic “quantum capacitance” of the electrode in terms of a fixed electronic density of states. Instead, we introduce a more accurate first-principles approach for directly simulatingmore » charge storage in model capacitors using the effective screening medium method, which implicitly accounts for the presence of the interfacial electric field. Applying this approach to graphene supercapacitor electrodes, we find that results differ significantly from the predictions of fixed-band models, leading to improved consistency with experimentally reported capacitive behavior. The differences are traced to two key factors: the inhomogeneous distribution of stored charge due to poor electronic screening and interfacial contributions from the specific interaction with the electrolyte. Lastly, our results are used to revise the conventional definition of quantum capacitance and to provide general strategies for improving electrochemical charge storage, particularly in graphene and similar low-dimensional materials.« less

Capacitive charge storage at an electrified interface investigated via direct first-principles simulations [Direct Simulation of Capacitive Charging of Graphene and Implications for Supercapacitor Design

DOE PAGES

Radin, Maxwell D.; Ogitsu, Tadashi; Biener, Juergen; ...

2015-03-11

Understanding the impact of interfacial electric fields on electronic structure is crucial to improving the performance of materials in applications based on charged interfaces. Supercapacitors store energy directly in the strong interfacial field between a solid electrode and a liquid electrolyte; however, the complex interplay between the two is often poorly understood, particularly for emerging low-dimensional electrode materials that possess unconventional electronic structure. Typical descriptions tend to neglect the specific electrode-electrolyte interaction, approximating the intrinsic “quantum capacitance” of the electrode in terms of a fixed electronic density of states. Instead, we introduce a more accurate first-principles approach for directly simulatingmore » charge storage in model capacitors using the effective screening medium method, which implicitly accounts for the presence of the interfacial electric field. Applying this approach to graphene supercapacitor electrodes, we find that results differ significantly from the predictions of fixed-band models, leading to improved consistency with experimentally reported capacitive behavior. The differences are traced to two key factors: the inhomogeneous distribution of stored charge due to poor electronic screening and interfacial contributions from the specific interaction with the electrolyte. Lastly, our results are used to revise the conventional definition of quantum capacitance and to provide general strategies for improving electrochemical charge storage, particularly in graphene and similar low-dimensional materials.« less

Explicit continuous charge-based compact model for long channel heavily doped surrounding-gate MOSFETs incorporating interface traps and quantum effects

NASA Astrophysics Data System (ADS)

Hamzah, Afiq; Hamid, Fatimah A.; Ismail, Razali

2016-12-01

An explicit solution for long-channel surrounding-gate (SRG) MOSFETs is presented from intrinsic to heavily doped body including the effects of interface traps and fixed oxide charges. The solution is based on the core SRGMOSFETs model of the Unified Charge Control Model (UCCM) for heavily doped conditions. The UCCM model of highly doped SRGMOSFETs is derived to obtain the exact equivalent expression as in the undoped case. Taking advantage of the undoped explicit charge-based expression, the asymptotic limits for below threshold and above threshold have been redefined to include the effect of trap states for heavily doped cases. After solving the asymptotic limits, an explicit mobile charge expression is obtained which includes the trap state effects. The explicit mobile charge model shows very good agreement with respect to numerical simulation over practical terminal voltages, doping concentration, geometry effects, and trap state effects due to the fixed oxide charges and interface traps. Then, the drain current is obtained using the Pao-Sah's dual integral, which is expressed as a function of inversion charge densities at the source/drain ends. The drain current agreed well with the implicit solution and numerical simulation for all regions of operation without employing any empirical parameters. A comparison with previous explicit models has been conducted to verify the competency of the proposed model with the doping concentration of 1× {10}19 {{cm}}-3, as the proposed model has better advantages in terms of its simplicity and accuracy at a higher doping concentration.

Superficial Collagen Fibril Modulus and Pericellular Fixed Charge Density Modulate Chondrocyte Volumetric Behaviour in Early Osteoarthritis

PubMed Central

Turunen, Siru M.; Han, Sang Kuy; Herzog, Walter; Korhonen, Rami K.

2013-01-01

The aim of this study was to investigate if the experimentally detected altered chondrocyte volumetric behavior in early osteoarthritis can be explained by changes in the extracellular and pericellular matrix properties of cartilage. Based on our own experimental tests and the literature, the structural and mechanical parameters for normal and osteoarthritic cartilage were implemented into a multiscale fibril-reinforced poroelastic swelling model. Model simulations were compared with experimentally observed cell volume changes in mechanically loaded cartilage, obtained from anterior cruciate ligament transected rabbit knees. We found that the cell volume increased by 7% in the osteoarthritic cartilage model following mechanical loading of the tissue. In contrast, the cell volume decreased by 4% in normal cartilage model. These findings were consistent with the experimental results. Increased local transversal tissue strain due to the reduced collagen fibril stiffness accompanied with the reduced fixed charge density of the pericellular matrix could increase the cell volume up to 12%. These findings suggest that the increase in the cell volume in mechanically loaded osteoarthritic cartilage is primarily explained by the reduction in the pericellular fixed charge density, while the superficial collagen fibril stiffness is suggested to contribute secondarily to the cell volume behavior. PMID:23634175

Excitation of Kelvin Helmholtz instability by an ion beam in a plasma with negatively charged dust grains

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

Rani, Kavita; Sharma, Suresh C.

2015-02-15

An ion beam propagating through a magnetized dusty plasma drives Kelvin Helmholtz Instability (KHI) via Cerenkov interaction. The frequency of the unstable wave increases with the relative density of negatively charged dust grains. It is observed that the beam has stabilizing effect on the growth rate of KHI for low shear parameter, but for high shear parameter, the instability is destabilized with relative density of negatively charged dust grains.

Tribological Properties of Nanodiamonds in Aqueous Suspensions: Effect of the Surface Charge

NASA Astrophysics Data System (ADS)

Krim, J.; Liu, Zijian; Leininger, D. A.; Kooviland, A.; Smirnov, A. I.; Shendarova, O.; Brenner, D. W.

The presence of granular nanoparticulates, be they wear particles created naturally by frictional rubbing at a geological fault line or products introduced as lubricant additives, can dramatically alter friction at solid-liquid interfaces. Given the complexity of such systems, understanding system properties at a fundamental level is particularly challenging. The Quartz Crystal Microbalance (QCM) is an ideal tool for studies of material-liquid-nanoparticulate interfaces. We have employed it here to study the uptake and nanotribological properties of positively and negatively charged 5-15 nm diameter nanodiamonds dispersed in water[1] in the both the presence and absence of a macroscopic contact with the QCM electrode. The nanodiamonds were found to impact tribological performance at both nanometer and macroscopic scales. The tribological effects were highly sensitive to the sign of the charge: negatively (positively) charged particles were more weakly (strongly) bound and reduced (increased) frictional drag at the solid-liquid interface. For the macroscopic contacts, negatively charged nanodiamonds appeared to be displaced from the contact, while the positively charged ones were not. Overall, the negatively charged nanodiamonds were more stable in an aqueous dispersion for extended time periods. Work supported by NSF and DOE.

Effects of adhesions of amorphous Fe and Al hydroxides on surface charge and adsorption of K+ and Cd2+ on rice roots.

PubMed

Liu, Zhao-Dong; Wang, Hai-Cui; Zhou, Qin; Xu, Ren-Kou

2017-11-01

Iron (Fe) and aluminum (Al) hydroxides in variable charge soils attached to rice roots may affect surface-charge properties and subsequently the adsorption and uptake of nutrients and toxic metals by the roots. Adhesion of amorphous Fe and Al hydroxides onto rice roots and their effects on zeta potential of roots and adsorption of potassium (K + ) and cadmium (Cd 2+ ) by roots were investigated. Rice roots adsorbed more Al hydroxide than Fe hydroxide because of the greater positive charge on Al hydroxide. Adhesion of Fe and Al hydroxides decreased the negative charge on rice roots, and a greater effect of the Al hydroxide. Consequently, adhesion of Fe and Al hydroxides reduced the K + and Cd 2+ adsorption by rice roots. The results of attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and desorption of K + and Cd 2+ from rice roots indicated that physical masking by Fe and Al hydroxides and diffuse-layer overlapping between the positively-charged hydroxides and negatively-charged roots were responsible for the reduction of negative charge on roots induced by adhesion of the hydroxides. Therefore, the interaction between Fe and Al hydroxides and rice roots reduced negative charge on roots and thus inhibited their adsorption of nutrient and toxic cations. Copyright © 2017 Elsevier Inc. All rights reserved.

Positive zeta potential of a negatively charged semi-permeable plasma membrane

NASA Astrophysics Data System (ADS)

Sinha, Shayandev; Jing, Haoyuan; Das, Siddhartha

2017-08-01

The negative charge of the plasma membrane (PM) severely affects the nature of moieties that may enter or leave the cells and controls a large number of ion-interaction-mediated intracellular and extracellular events. In this letter, we report our discovery of a most fascinating scenario, where one interface (e.g., membrane-cytosol interface) of the negatively charged PM shows a positive surface (or ζ) potential, while the other interface (e.g., membrane-electrolyte interface) still shows a negative ζ potential. Therefore, we encounter a completely unexpected situation where an interface (e.g., membrane-cytosol interface) that has a negative surface charge density demonstrates a positive ζ potential. We establish that the attainment of such a property by the membrane can be ascribed to an interplay of the nature of the membrane semi-permeability and the electrostatics of the electric double layer established on either side of the charged membrane. We anticipate that such a membrane property can lead to such capabilities of the cell (in terms of accepting or releasing certain kinds of moieties as well regulating cellular signaling) that was hitherto inconceivable.

77 FR 40398 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Order Approving Proposed Rule...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-09

... prices of financial products that have maturity dates in the future as part of the volatility model in... Volatility Model in Its Clearing Fund Formula July 2, 2012. I. Introduction On May 15, 2012, the Fixed Income... simulation model currently used to calculate the VaR Charge in GSD's Clearing Fund formula is driven by...

75 FR 48734 - Self-Regulatory Organizations; EDGX Exchange, Inc.; Notice of Filing and Immediate Effectiveness...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-11

...) ISE FIX Session Fees The Exchange proposes to charge for legacy ISE \\4\\ Financial Information Exchange...-79). \\5\\ As stated in SR-ISE-2007-79, the ISE used the Financial Information Exchange (FIX) protocol... will provide Members a $0.0031 rebate per share for liquidity added on EDGX if the Member on a daily...

48 CFR 52.247-37 - F.o.b. Vessel, Port of Shipment.

Code of Federal Regulations, 2011 CFR

2011-10-01

... conformance with carrier requirements to protect the goods and to ensure assessment of the lowest applicable transportation charge; (2)(i) Deliver the shipment on board the ocean vessel in good order and condition on the date or within the period fixed; and (ii) Pay and bear all charges incurred in placing the shipment...

48 CFR 47.303-9 - F.o.b. vessel, port of shipment.

Code of Federal Regulations, 2012 CFR

2012-10-01

... conformance with carrier requirements to protect the goods and to ensure assessment of the lowest applicable transportation charge; (2)(i) Deliver the shipment on board the ocean vessel in good order and condition on the date or within the period fixed; and (ii) Pay and bear all charges incurred in placing the shipment...

48 CFR 47.303-9 - F.o.b. vessel, port of shipment.

Code of Federal Regulations, 2014 CFR

2014-10-01

... conformance with carrier requirements to protect the goods and to ensure assessment of the lowest applicable transportation charge; (2)(i) Deliver the shipment on board the ocean vessel in good order and condition on the date or within the period fixed; and (ii) Pay and bear all charges incurred in placing the shipment...

48 CFR 52.247-37 - F.o.b. Vessel, Port of Shipment.

Code of Federal Regulations, 2013 CFR

2013-10-01

... conformance with carrier requirements to protect the goods and to ensure assessment of the lowest applicable transportation charge; (2)(i) Deliver the shipment on board the ocean vessel in good order and condition on the date or within the period fixed; and (ii) Pay and bear all charges incurred in placing the shipment...

48 CFR 52.247-37 - F.o.b. Vessel, Port of Shipment.

Code of Federal Regulations, 2012 CFR

2012-10-01

... conformance with carrier requirements to protect the goods and to ensure assessment of the lowest applicable transportation charge; (2)(i) Deliver the shipment on board the ocean vessel in good order and condition on the date or within the period fixed; and (ii) Pay and bear all charges incurred in placing the shipment...

48 CFR 47.303-9 - F.o.b. vessel, port of shipment.

Code of Federal Regulations, 2013 CFR

2013-10-01

... conformance with carrier requirements to protect the goods and to ensure assessment of the lowest applicable transportation charge; (2)(i) Deliver the shipment on board the ocean vessel in good order and condition on the date or within the period fixed; and (ii) Pay and bear all charges incurred in placing the shipment...

48 CFR 47.303-9 - F.o.b. vessel, port of shipment.

Code of Federal Regulations, 2011 CFR

2011-10-01

... conformance with carrier requirements to protect the goods and to ensure assessment of the lowest applicable transportation charge; (2)(i) Deliver the shipment on board the ocean vessel in good order and condition on the date or within the period fixed; and (ii) Pay and bear all charges incurred in placing the shipment...

48 CFR 52.247-37 - F.o.b. Vessel, Port of Shipment.

Code of Federal Regulations, 2014 CFR

2014-10-01

... conformance with carrier requirements to protect the goods and to ensure assessment of the lowest applicable transportation charge; (2)(i) Deliver the shipment on board the ocean vessel in good order and condition on the date or within the period fixed; and (ii) Pay and bear all charges incurred in placing the shipment...

Evaluation of the constant potential method in simulating electric double-layer capacitors

NASA Astrophysics Data System (ADS)

Wang, Zhenxing; Yang, Yang; Olmsted, David L.; Asta, Mark; Laird, Brian B.

2014-11-01

A major challenge in the molecular simulation of electric double layer capacitors (EDLCs) is the choice of an appropriate model for the electrode. Typically, in such simulations the electrode surface is modeled using a uniform fixed charge on each of the electrode atoms, which ignores the electrode response to local charge fluctuations in the electrolyte solution. In this work, we evaluate and compare this Fixed Charge Method (FCM) with the more realistic Constant Potential Method (CPM), [S. K. Reed et al., J. Chem. Phys. 126, 084704 (2007)], in which the electrode charges fluctuate in order to maintain constant electric potential in each electrode. For this comparison, we utilize a simplified LiClO4-acetonitrile/graphite EDLC. At low potential difference (ΔΨ ⩽ 2 V), the two methods yield essentially identical results for ion and solvent density profiles; however, significant differences appear at higher ΔΨ. At ΔΨ ⩾ 4 V, the CPM ion density profiles show significant enhancement (over FCM) of "inner-sphere adsorbed" Li+ ions very close to the electrode surface. The ability of the CPM electrode to respond to local charge fluctuations in the electrolyte is seen to significantly lower the energy (and barrier) for the approach of Li+ ions to the electrode surface.

Capacitive charge storage at an electrified interface investigated via direct first-principles simulations

NASA Astrophysics Data System (ADS)

Radin, Maxwell D.; Ogitsu, Tadashi; Biener, Juergen; Otani, Minoru; Wood, Brandon C.

2015-03-01

Understanding the impact of interfacial electric fields on electronic structure is crucial to improving the performance of materials in applications based on charged interfaces. Supercapacitors store energy directly in the strong interfacial field between a solid electrode and a liquid electrolyte; however, the complex interplay between the two is often poorly understood, particularly for emerging low-dimensional electrode materials that possess unconventional electronic structure. Typical descriptions tend to neglect the specific electrode-electrolyte interaction, approximating the intrinsic "quantum capacitance" of the electrode in terms of a fixed electronic density of states. Instead, we introduce a more accurate first-principles approach for directly simulating charge storage in model capacitors using the effective screening medium method, which implicitly accounts for the presence of the interfacial electric field. Applying this approach to graphene supercapacitor electrodes, we find that results differ significantly from the predictions of fixed-band models, leading to improved consistency with experimentally reported capacitive behavior. The differences are traced to two key factors: the inhomogeneous distribution of stored charge due to poor electronic screening and interfacial contributions from the specific interaction with the electrolyte. Our results are used to revise the conventional definition of quantum capacitance and to provide general strategies for improving electrochemical charge storage, particularly in graphene and similar low-dimensional materials.

Superposition Principle in Auger Recombination of Charged and Neutral Multicarrier States in Semiconductor Quantum Dots

DOE PAGES

Wu, Kaifeng; Lim, Jaehoon; Klimov, Victor I.

2017-07-19

Application of colloidal semiconductor quantum dots (QDs) in optical and optoelectronic devices is often complicated by unintentional generation of extra charges, which opens fast nonradiative Auger recombination pathways whereby the recombination energy of an exciton is quickly transferred to the extra carrier(s) and ultimately dissipated as heat. Previous studies of Auger recombination have primarily focused on neutral and, more recently, negatively charged multicarrier states. Auger dynamics of positively charged species remains more poorly explored due to difficulties in creating, stabilizing, and detecting excess holes in the QDs. Here we apply photochemical doping to prepare both negatively and positively charged CdSe/CdSmore » QDs with two distinct core/shell interfacial profiles (“sharp” versus “smooth”). Using neutral and charged QD samples we evaluate Auger lifetimes of biexcitons, negative and positive trions (an exciton with an extra electron or a hole, respectively), and multiply negatively charged excitons. Using these measurements, we demonstrate that Auger decay of both neutral and charged multicarrier states can be presented as a superposition of independent elementary three-particle Auger events. As one of the manifestations of the superposition principle, we observe that the biexciton Auger decay rate can be presented as a sum of the Auger rates for independent negative and positive trion pathways. Furthermore, by comparing the measurements on the QDs with the “sharp” versus “smooth” interfaces, we also find that while affecting the absolute values of Auger lifetimes, manipulation of the shape of the confinement potential does not lead to violation of the superposition principle, which still allows us to accurately predict the biexciton Auger lifetimes based on the measured negative and positive trion dynamics. Our findings indicate considerable robustness of the superposition principle as applied to Auger decay of charged and neutral multicarrier states, suggesting its generality to quantum-confined nanocrystals of arbitrary compositions and complexities.« less

Superposition Principle in Auger Recombination of Charged and Neutral Multicarrier States in Semiconductor Quantum Dots.

PubMed

Wu, Kaifeng; Lim, Jaehoon; Klimov, Victor I

2017-08-22

Application of colloidal semiconductor quantum dots (QDs) in optical and optoelectronic devices is often complicated by unintentional generation of extra charges, which opens fast nonradiative Auger recombination pathways whereby the recombination energy of an exciton is quickly transferred to the extra carrier(s) and ultimately dissipated as heat. Previous studies of Auger recombination have primarily focused on neutral and, more recently, negatively charged multicarrier states. Auger dynamics of positively charged species remains more poorly explored due to difficulties in creating, stabilizing, and detecting excess holes in the QDs. Here we apply photochemical doping to prepare both negatively and positively charged CdSe/CdS QDs with two distinct core/shell interfacial profiles ("sharp" versus "smooth"). Using neutral and charged QD samples we evaluate Auger lifetimes of biexcitons, negative and positive trions (an exciton with an extra electron or a hole, respectively), and multiply negatively charged excitons. Using these measurements, we demonstrate that Auger decay of both neutral and charged multicarrier states can be presented as a superposition of independent elementary three-particle Auger events. As one of the manifestations of the superposition principle, we observe that the biexciton Auger decay rate can be presented as a sum of the Auger rates for independent negative and positive trion pathways. By comparing the measurements on the QDs with the "sharp" versus "smooth" interfaces, we also find that while affecting the absolute values of Auger lifetimes, manipulation of the shape of the confinement potential does not lead to violation of the superposition principle, which still allows us to accurately predict the biexciton Auger lifetimes based on the measured negative and positive trion dynamics. These findings indicate considerable robustness of the superposition principle as applied to Auger decay of charged and neutral multicarrier states, suggesting its generality to quantum-confined nanocrystals of arbitrary compositions and complexities.

Comment on 'The effect of liquid water on thunderstorm charging' by C.P.R. Saunders et al

NASA Technical Reports Server (NTRS)

Williams, Earle; Zhang, Renyi

1993-01-01

This paper is a comment on the claims made in the paper by Saunders et al. (1991), which reports on a laboratory simulation of ice particle charging in thunderstorms, concerning the microphysical condition of riming ice particles and the conditions for sublimation and negative charging in thunderclouds. It is argued that the interpretation of Saunders is contrary to the findings of Williams et al. (1991), which support the hypothesis that sublimating graupel charge negatively (in collision with smaller ice particles) and graupel in deposition charge positively. Based on microphysical calculations as well as observations in thunderclouds, it is concluded that, while sublimation of the rimer surface and negative charging do not appear to account for the laboratory observations reported by Saunders et al., these authors do not have sufficient evidence for rejecting the sublimation hypothesis presented by Williams et al. (1991) for thunderstorms.

Electrostatic Power Generation from Negatively Charged, Simulated Lunar Regolith

NASA Technical Reports Server (NTRS)

Choi, Sang H.; King, Glen C.; Kim, Hyun-Jung; Park, Yeonjoon

2010-01-01

Research was conducted to develop an electrostatic power generator for future lunar missions that facilitate the utilization of lunar resources. The lunar surface is known to be negatively charged from the constant bombardment of electrons and protons from the solar wind. The resulting negative electrostatic charge on the dust particles, in the lunar vacuum, causes them to repel each other minimizing the potential. The result is a layer of suspended dust about one meter above the lunar surface. This phenomenon was observed by both Clementine and Surveyor spacecrafts. During the Apollo 17 lunar landing, the charged dust was a major hindrance, as it was attracted to the astronauts' spacesuits, equipment, and the lunar buggies. The dust accumulated on the spacesuits caused reduced visibility for the astronauts, and was unavoidably transported inside the spacecraft where it caused breathing irritation [1]. In the lunar vacuum, the maximum charge on the particles can be extremely high. An article in the journal "Nature", titled "Moon too static for astronauts?" (Feb 2, 2007) estimates that the lunar surface is charged with up to several thousand volts [2]. The electrostatic power generator was devised to alleviate the hazardous effects of negatively charged lunar soil by neutralizing the charged particles through capacitive coupling and thereby simultaneously harnessing power through electric charging [3]. The amount of power generated or collected is dependent on the areal coverage of the device and hovering speed over the lunar soil surface. A thin-film array of capacitors can be continuously charged and sequentially discharged using a time-differentiated trigger discharge process to produce a pulse train of discharge for DC mode output. By controlling the pulse interval, the DC mode power can be modulated for powering devices and equipment. In conjunction with a power storage system, the electrostatic power generator can be a power source for a lunar rover or other systems. The negatively charged lunar soil would also be neutralized mitigating some of the adverse effects resulting from lunar dust.

Avoiding revenue loss due to 'lesser of' contract clauses.

PubMed

Stodolak, Frederick; Gutierrez, Henry

2014-08-01

Finance managers seeking to avoid lost revenue attributable to lesser-of-charge-or-fixed-fee (lesser-of) clauses in their contracts should: Identify payer contracts that contain lesser-of clauses. Prepare lesser-of lost-revenue reports for non-bundled and bundled rates. For claims with covered charges below the bundled rate, identify service codes associated with the greatest proportion of total gross revenue and determine new, higher charge levels for those codes. Establish an approach for setting charges for non-bundled fee schedules to address lost-revenue-related issues. Incorporate changes into overall strategic or hospital zero-based pricing modeling and parameters.

Gauge fixing and BFV quantization

NASA Astrophysics Data System (ADS)

Rogers, Alice

2000-01-01

Non-singularity conditions are established for the Batalin-Fradkin-Vilkovisky (BFV) gauge-fixing fermion which are sufficient for it to lead to the correct path integral for a theory with constraints canonically quantized in the BFV approach. The conditions ensure that the anticommutator of this fermion with the BRST charge regularizes the path integral by regularizing the trace over non-physical states in each ghost sector. The results are applied to the quantization of a system which has a Gribov problem, using a non-standard form of the gauge-fixing fermion.

Holographic Van der Waals phase transition of the higher-dimensional electrically charged hairy black hole

NASA Astrophysics Data System (ADS)

Li, Hui-Ling; Feng, Zhong-Wen; Zu, Xiao-Tao

2018-01-01

With motivation by holography, employing black hole entropy, two-point connection function and entanglement entropy, we show that, for the higher-dimensional Anti-de Sitter charged hairy black hole in the fixed charged ensemble, a Van der Waals-like phase transition can be observed. Furthermore, based on the Maxwell equal-area construction, we check numerically the equal-area law for a first order phase transition in order to further characterize the Van der Waals-like phase transition.

Protein charge distribution in proteomes and its impact on translation

PubMed Central

Requião, Rodrigo D.; Fernandes, Luiza; de Souza, Henrique José Araujo; Rossetto, Silvana; Domitrovic, Tatiana

2017-01-01

As proteins are synthesized, the nascent polypeptide must pass through a negatively charged exit tunnel. During this stage, positively charged stretches can interact with the ribosome walls and slow the translation. Therefore, charged polypeptides may be important factors that affect protein expression. To determine the frequency and distribution of positively and negatively charged stretches in different proteomes, the net charge was calculated for every 30 consecutive amino acid residues, which corresponds to the length of the ribosome exit tunnel. The following annotated and reviewed proteins in the UniProt database (Swiss-Prot) were analyzed: 551,705 proteins from different organisms and a total of 180 million protein segments. We observed that there were more negative than positive stretches and that super-charged positive sequences (i.e., net charges ≥ 14) were underrepresented in the proteomes. Overall, the proteins were more positively charged at their N-termini and C-termini, and this feature was present in most organisms and subcellular localizations. To investigate whether the N-terminal charges affect the elongation rates, previously published ribosomal profiling data obtained from S. cerevisiae, without translation-interfering drugs, were analyzed. We observed a nonlinear effect of the charge on the ribosome occupancy in which values ≥ +5 and ≤ -6 showed increased and reduced ribosome densities, respectively. These groups also showed different distributions across 80S monosomes and polysomes. Basic polypeptides are more common within short proteins that are translated by monosomes, whereas negative stretches are more abundant in polysome-translated proteins. These findings suggest that the nascent peptide charge impacts translation and can be one of the factors that regulate translation efficiency and protein expression. PMID:28531225

On charging of snow particles in blizzard

NASA Technical Reports Server (NTRS)

Shio, Hisashi

1991-01-01

The causes of the charge polarity on the blizzard, which consisted of fractured snow crystals and ice particles, were investigated. As a result, the charging phenomena showed that the characteristics of the blizzard are as follows: (1) In the case of the blizzard with snowfall, the fractured snow particles drifting near the surface of snow field (lower area: height 0.3 m) had positive charge, while those drifting at higher area (height 2 m) from the surface of snow field had negative charge. However, during the series of blizzards two kinds of particles positively and negatively charged were collected in equal amounts in a Faraday Cage. It may be considered that snow crystals with electrically neutral properties were separated into two kinds of snow flakes (charged positively and negatively) by destruction of the snow crystals. (2) In the case of the blizzard which consisted of irregularly formed ice drops (generated by peeling off the hardened snow field), the charge polarity of these ice drops salting over the snow field was particularly controlled by the crystallographic characteristics of the surface of the snow field hardened by the powerful wind pressure.

An electrostatic charge measurement of blowing snow particles focusing on collision frequency to the snow surface

NASA Astrophysics Data System (ADS)

Omiya, S.; Sato, A.

2010-12-01

Blowing snow particles are known to have an electrostatic charge. This charge may be a contributing factor in the formation of snow drifts and snow cornices and changing of the trajectory of blowing snow particles. These formations and phenomena can cause natural disaster such as an avalanche and a visibility deterioration, and obstruct transportation during winter season. Therefore, charging phenomenon of the blowing snow particles is an important issue in terms of not only precise understanding of the particle motion but disaster prevention. The primary factor of charge accumulation to the blowing snow particles is thought to be due to “saltation” of them. The “saltation” is one of movement forms of blowing snow: when the snow particles are transported by the wind, they repeat frictional collisions with the snow surface. In previous studies, charge-to-mass ratios measured in the field were approximately -50 to -10 μC/kg, and in the wind tunnel were approximately -0.8 to -0.1 μC/kg. While there were qualitatively consistent in sign, negative, there were huge gaps quantitatively between them. One reason of those gaps is speculated to be due to differences in fetch. In other words, the difference of the collision frequency of snow particles to the snow surface has caused the gaps. But it is merely a suggestion and that has not been confirmed. The purpose of this experiment is to measure the charge of blowing snow particles focusing on the collision frequency and clarify the relationship between them. Experiments were carried out in the cryogenic wind tunnel of Snow and Ice Research Center (NIED, JAPAN). A Faraday cage and an electrometer were used to measure the charge of snow particles. These experiments were conducted over the hard snow surface condition to prevent the erosion of the snow surface and the generation of new snow particles from the surface. The collision frequency of particle was controlled by changing the wind velocity (4.5 to 7 m/s) under the fixed fetch (12m). The number of collisions of particle was converted from the wind velocity using an equation obtained by Kosugi et al. (2004). Blowing snow particles tend to accumulate negative charges gradually with increase of the number of collisions to the snow surface. As a result, it is demonstrated that the gaps between the field values and the wind tunnel ones were due to difference of the collision frequency of snow particles. Assuming a logarithmic relationship as first approximation between the measured charges and the number of collisions, the charge-to-mass ratios will reach roughly the same value which was obtained in the field with several hundreds collisions. For instance, fetch is needed roughly 200m for blowing snow particles to gain -30 μC/kg under the following conditions: air temperature -20 degrees Celsius, wind velocity 7m/s and hard snow surface. REFERENCE: Kosugi et al., (2004): Dependence of drifting snow saltation length on snow surface hardness. Cold Reg. Sci. Technol., 39, 133-139.

NOVA SCIENCE UNIT 15, FUNDAMENTAL PARTICLES 4.

ERIC Educational Resources Information Center

1964

THE PRINCIPLES OF ATOMIC STRUCTURE WHICH ARE STRESSED ARE THAT ATOMS ARE MADE UP OF A NUCLEUS WITH A POSITIVE CHARGE, SURROUNDED BY ELECTRONS WITH A NEGATIVE CHARGE, AND THAT THERE IS NO CHANGE IN THE ATOM WHEN THE POSITIVE AND NEGATIVE CHARGES ARE EQUAL. EXPERIMENTS ILLUSTRATE THAT CURRENT ELECTRICITY IS ACTUALLY ELECTRONS IN MOTION, THAT THERE…

Photoinduced ultrafast charge-order melting: Charge-order inversion and nonthermal effects

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

van Veenendaal, Michel

2016-09-01

The effect of photoexcitation is studied for a system with checkerboard charge order induced by displacements of ligands around a metal site. The motion of the ligands is treated classically and the electronic charges are simplified to two-level molecular bond charges. The calculations are done for a checkerboard charge-ordered system with about 100 000 ligand oscillators coupled to a fixed-temperature bath. The initial photoexcitation is followed by a rapid decrease in the charge-order parameter within 50–100 femtoseconds while leaving the correlation length almost unchanged. Depending on the fluence, a complete melting of the charge order occurs in less than amore » picosecond. While for low fluences, the system returns to its original state, for full melting, it recovers to its broken-symmetry state leading to an inversion of the charge order. For small long-range interactions, recovery can be slow due to domain formation.« less

Photoinduced ultrafast charge-order melting: Charge-order inversion and nonthermal effects

DOE PAGES

van Veenendaal, Michel

2016-09-01

The effect of photoexcitation is studied for a system with checkerboard charge order induced by displacements of ligands around a metal site. The motion of the ligands is treated classically and the electronic charges are simplified to two-level molecular bond charges. The calculations are done for a checkerboard charge-ordered system with about 100 000 ligand oscillators coupled to a fixed-temperature bath. The initial photoexcitation is followed by a rapid decrease in the charge-order parameter within 50–100 femtoseconds while leaving the correlation length almost unchanged. Depending on the fluence, a complete melting of the charge order occurs in less than amore » picosecond. While for low fluences, the system returns to its original state, for full melting, it recovers to its broken-symmetry state leading to an inversion of the charge order. Finally, for small long-range interactions, recovery can be slow due to domain formation.« less

A Power-Efficient Wireless Capacitor Charging System Through an Inductive Link

PubMed Central

Lee, Hyung-Min; Ghovanloo, Maysam

2014-01-01

A power-efficient wireless capacitor charging system for inductively powered applications has been presented. A bank of capacitors can be directly charged from an ac source by generating a current through a series charge injection capacitor and a capacitor charger circuit. The fixed charging current reduces energy loss in switches, while maximizing the charging efficiency. An adaptive capacitor tuner compensates for the resonant capacitance variations during charging to keep the amplitude of the ac input voltage at its peak. We have fabricated the capacitor charging system prototype in a 0.35-μm 4-metal 2-poly standard CMOS process in 2.1 mm2 of chip area. It can charge four pairs of capacitors sequentially. While receiving 2.7-V peak ac input through a 2-MHz inductive link, the capacitor charging system can charge each pair of 1 μF capacitors up to ±2 V in 420 μs, achieving a high measured charging efficiency of 82%. PMID:24678284

A Power-Efficient Wireless Capacitor Charging System Through an Inductive Link.

PubMed

Lee, Hyung-Min; Ghovanloo, Maysam

2013-10-01

A power-efficient wireless capacitor charging system for inductively powered applications has been presented. A bank of capacitors can be directly charged from an ac source by generating a current through a series charge injection capacitor and a capacitor charger circuit. The fixed charging current reduces energy loss in switches, while maximizing the charging efficiency. An adaptive capacitor tuner compensates for the resonant capacitance variations during charging to keep the amplitude of the ac input voltage at its peak. We have fabricated the capacitor charging system prototype in a 0.35- μ m 4-metal 2-poly standard CMOS process in 2.1 mm 2 of chip area. It can charge four pairs of capacitors sequentially. While receiving 2.7-V peak ac input through a 2-MHz inductive link, the capacitor charging system can charge each pair of 1 μ F capacitors up to ±2 V in 420 μ s, achieving a high measured charging efficiency of 82%.

Functions Character

NASA Astrophysics Data System (ADS)

Dugave, Maxime; Göhmann, Frank; Kozlowski, Karol Kajetan

2014-04-01

We establish several properties of the solutions to the linear integral equations describing the infinite volume properties of the XXZ spin-1/2 chain in the disordered regime. In particular, we obtain lower and upper bounds for the dressed energy, dressed charge and density of Bethe roots. Furthermore, we establish that given a fixed external magnetic field (or a fixed magnetization) there exists a unique value of the boundary of the Fermi zone.

The surface charge of trypanosomatids.

PubMed

Souto-Padrón, Thaïs

2002-12-01

The surface charge of trypanosomatids was evaluated by means of the binding of cationic particles, as visualized by electron microscopy and by direct measurements of the electrophoretic mobility of cells. The results obtained indicate that most of the trypanosomatids exhibit a negatively charged surface whose value is species specific and varies according to the developmental stages. Sialic acids associated with glycoproteins, glycolipids and phosphate groups are the major components responsible for the net negative surface charge of the trypanosomatids.

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.

On Born's Conjecture about Optimal Distribution of Charges for an Infinite Ionic Crystal

NASA Astrophysics Data System (ADS)

Bétermin, Laurent; Knüpfer, Hans

2018-04-01

We study the problem for the optimal charge distribution on the sites of a fixed Bravais lattice. In particular, we prove Born's conjecture about the optimality of the rock salt alternate distribution of charges on a cubic lattice (and more generally on a d-dimensional orthorhombic lattice). Furthermore, we study this problem on the two-dimensional triangular lattice and we prove the optimality of a two-component honeycomb distribution of charges. The results hold for a class of completely monotone interaction potentials which includes Coulomb-type interactions for d≥3 . In a more general setting, we derive a connection between the optimal charge problem and a minimization problem for the translated lattice theta function.

Mechanisms of Polyelectrolyte Enhanced Surfactant Adsorption at the Air-Water Interface

PubMed Central

Stenger, Patrick C.; Palazoglu, Omer A.; Zasadzinski, Joseph A.

2009-01-01

Chitosan, a naturally occurring cationic polyelectrolyte, restores the adsorption of the clinical lung surfactant Survanta to the air-water interface in the presence of albumin at much lower concentrations than uncharged polymers such as polyethylene glycol. This is consistent with the positively charged chitosan forming ion pairs with negative charges on the albumin and lung surfactant particles, reducing the net charge in the double-layer, and decreasing the electrostatic energy barrier to adsorption to the air-water interface. However, chitosan, like other polyelectrolytes, cannot perfectly match the charge distribution on the surfactant, which leads to patches of positive and negative charge at net neutrality. Increasing the chitosan concentration further leads to a reduction in the rate of surfactant adsorption consistent with an over-compensation of the negative charge on the surfactant and albumin surfaces, which creates a new repulsive electrostatic potential between the now cationic surfaces. This charge neutralization followed by charge inversion explains the window of polyelectrolyte concentration that enhances surfactant adsorption; the same physical mechanism is observed in flocculation and re-stabilization of anionic colloids by chitosan and in alternate layer deposition of anionic and cationic polyelectrolytes on charged colloids. PMID:19366599

Mechanisms of polyelectrolyte enhanced surfactant adsorption at the air-water interface.

PubMed

Stenger, Patrick C; Palazoglu, Omer A; Zasadzinski, Joseph A

2009-05-01

Chitosan, a naturally occurring cationic polyelectrolyte, restores the adsorption of the clinical lung surfactant Survanta to the air-water interface in the presence of albumin at much lower concentrations than uncharged polymers such as polyethylene glycol. This is consistent with the positively charged chitosan forming ion pairs with negative charges on the albumin and lung surfactant particles, reducing the net charge in the double-layer, and decreasing the electrostatic energy barrier to adsorption to the air-water interface. However, chitosan, like other polyelectrolytes, cannot perfectly match the charge distribution on the surfactant, which leads to patches of positive and negative charge at net neutrality. Increasing the chitosan concentration further leads to a reduction in the rate of surfactant adsorption consistent with an over-compensation of the negative charge on the surfactant and albumin surfaces, which creates a new repulsive electrostatic potential between the now cationic surfaces. This charge neutralization followed by charge inversion explains the window of polyelectrolyte concentration that enhances surfactant adsorption; the same physical mechanism is observed in flocculation and re-stabilization of anionic colloids by chitosan and in alternate layer deposition of anionic and cationic polyelectrolytes on charged colloids.

Concordance of gross surgical and final fixed margins in vulvar intraepithelial neoplasia 3 and vulvar cancer.

PubMed

DeSimone, Christopher P; Crisp, Meredith P; Ueland, Frederick R; DePriest, Paul D; van Nagell, John R; Lele, Subodh M; Modesitt, Susan C

2006-08-01

To prospectively evaluate the concordance of initial surgical vulvar margins and final fixed margins and to determine the amount of microscopic pathology of grossly negative margins in women with vulvar intraepithelial neoplasia (VIN) 3 or vulvar carcinoma. Women with VIN 3 or vulvar carcinoma undergoing surgical excision were identified. Prior to excision, acetic acid was used to highlight the lesions, and 2 sutures were placed, 1 at the edge of gross disease and another 1 cm distal from the first. After specimen removal and fixation, the distance between sutures and microscopic involvement of VIN was determined. Twenty-seven women were enrolled; however, only 19 had final fixed specimens that could be accurately measured. The median fixed distance of the vulvar margin was 0.85 cm (mean, 0.83; SD, 0.19) as compared to the gross, 1-cm margin (p = 0.001). Three subjects (16%) had microscopic involvement by VIN 3 in the grossly negative epithelium between the 2 sutures, but none had a positive peripheral margin. The gross surgical margin after vulvar resection is reduced by 15% when measured in its final fixed state, and a grossly negative 1-cm margin will seldom harbor significant disease.

Triboelectricity: macroscopic charge patterns formed by self-arraying ions on polymer surfaces.

PubMed

Burgo, Thiago A L; Ducati, Telma R D; Francisco, Kelly R; Clinckspoor, Karl J; Galembeck, Fernando; Galembeck, Sergio E

2012-05-15

Tribocharged polymers display macroscopically patterned positive and negative domains, verifying the fractal geometry of electrostatic mosaics previously detected by electric probe microscopy. Excess charge on contacting polyethylene (PE) and polytetrafluoroethylene (PTFE) follows the triboelectric series but with one caveat: net charge is the arithmetic sum of patterned positive and negative charges, as opposed to the usual assumption of uniform but opposite signal charging on each surface. Extraction with n-hexane preferentially removes positive charges from PTFE, while 1,1-difluoroethane and ethanol largely remove both positive and negative charges. Using suitable analytical techniques (electron energy-loss spectral imaging, infrared microspectrophotometry and carbonization/colorimetry) and theoretical calculations, the positive species were identified as hydrocarbocations and the negative species were identified as fluorocarbanions. A comprehensive model is presented for PTFE tribocharging with PE: mechanochemical chain homolytic rupture is followed by electron transfer from hydrocarbon free radicals to the more electronegative fluorocarbon radicals. Polymer ions self-assemble according to Flory-Huggins theory, thus forming the experimentally observed macroscopic patterns. These results show that tribocharging can only be understood by considering the complex chemical events triggered by mechanical action, coupled to well-established physicochemical concepts. Patterned polymers can be cut and mounted to make macroscopic electrets and multipoles.

Coarse-grained modeling of proline rich protein 1 (PRP-1) in bulk solution and adsorbed to a negatively charged surface.

PubMed

Skepö, Marie; Linse, Per; Arnebrant, Thomas

2006-06-22

Structural properties of the acidic proline rich protein PRP-1 of salivary origin in bulk solution and adsorbed onto a negatively charged surface have been studied by Monte Carlo simulations. A simple model system with focus on electrostatic interactions and short-ranged attractions among the uncharged amino acids has been used. In addition to PRP-1, some mutants were considered to assess the role of the interactions in the systems. Contrary to polyelectrolytes, the protein has a compact structure in salt-free bulk solutions, whereas at high salt concentration the protein becomes more extended. The protein adsorbs to a negatively charged surface, although its net charge is negative. The adsorbed protein displays an extended structure, which becomes more compact upon addition of salt. Hence, the conformational response upon salt addition in the adsorbed state is the opposite as compared to that in bulk solution. The conformational behavior of PRP-1 in bulk solution and at charged surfaces as well as its propensity to adsorb to surfaces with the same net charge are rationalized by the block polyampholytic character of the protein. The presence of a triad of positively charged amino acids in the C-terminal was found to be important for the adsorption of the protein.

Reversible Adhesion with Polyelectrolyte Brushes Tailored via the Uptake and Release of Trivalent Lanthanum Ions

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

Farina, Robert; Laugel, Nicolas; Yu, Jing

Applications of end-tethered polyelectrolyte “brushes” to modify solid surfaces have been developed and studied for their colloidal stabilization and high lubrication properties. Current efforts have expanded into biological realms and stimuli-responsive materials. Our work explores responsive and reversible aspects of polyelectrolyte brush behavior when polyelectrolyte chains interact with oppositely charged multivalent ions and complexes, which act as counterions. There is a significant void in the polyelectrolyte literature regarding interactions with multivalent species. This paper demonstrates that interactions between solid surfaces bearing negatively charged polyelectrolyte brushes are highly sensitive to the presence of trivalent lanthanum, La3+. Lanthanum cations have unique interactionsmore » with polyelectrolyte chains, in part due to their small size and hydration radius which results in a high local charge density. Using La3+ in conjunction with the surface forces apparatus (SFA), adhesion has been observed to reversibly appear and disappear upon the uptake and release, respectively, of these multivalent cations acting as counterions. In media of fixed ionic strength set by monovalent sodium salt, at I0 = 0.003 M and I0 = 0.3 M, the sign of the interaction forces between overlapping brushes changes from repulsive to attractive when La3+ concentrations reach 0.1 mol % of the total ion concentration. These results are also shown to be generally consistent with, but subtlety different from, previous polyelectrolyte brush experiments using trivalent ruthenium hexamine in the role of the multivalent counterion.« less

VHF lightning mapping observations of a triggered lightning flash

NASA Astrophysics Data System (ADS)

Edens, H. E.; Eack, K. B.; Eastvedt, E. M.; Trueblood, J. J.; Winn, W. P.; Krehbiel, P. R.; Aulich, G. D.; Hunyady, S. J.; Murray, W. C.; Rison, W.; Behnke, S. A.; Thomas, R. J.

2012-10-01

On 3 August 2010 an extensive lightning flash was triggered over Langmuir Laboratory in New Mexico. The upward positive leader propagated into the storm's midlevel negative charge region, extending over a horizontal area of 13 × 13 km and 7.5 km altitude. The storm had a normal-polarity tripolar charge structure with upper positive charge over midlevel negative charge. Lightning Mapping Array (LMA) observations were used to estimate positive leader velocities along various branches, which were in the range of 1-3 × 104 m s-1, slower than in other studies. The upward positive leader initiated at 3.4 km altitude, but was mapped only above 4.0 km altitude after the onset of retrograde negative breakdown, indicating a change in leader propagation and VHF emissions. The observations suggest that both positive and negative breakdown produce VHF emissions that can be located by time-of-arrival systems, and that not all VHF emissions occurring along positive leader channels are associated with retrograde negative breakdown.

Microgravity Experiments to Evaluate Electrostatic Forces in Controlling Cohesion and Adhesion of Granular Materials

NASA Technical Reports Server (NTRS)

Marshall, J.; Weislogel, M.; Jacobson, T.

1999-01-01

The bulk behavior of dispersed, fluidized, or undispersed stationary granular systems cannot be fully understood in terms of adhesive/cohesive properties without understanding the role of electrostatic forces acting at the level of the grains themselves. When grains adhere to a surface, or come in contact with one another in a stationary bulk mass, it is difficult to measure the forces acting on the grains, and the forces themselves that induced the cohesion and adhesion are changed. Even if a single gain were to be scrutinized in the laboratory, it might be difficult, perhaps impossible, to define the distribution and character of surface charging and the three- dimensional relationship that charges (electrons, holes) have to one another. The hypothesis that we propose to test in microgravity (for dielectric materials) is that adhesion and cohesion of granular matter are mediated primarily by dipole forces that do not require the presence of a net charge; in fact, nominally electrically neutral materials should express adhesive and cohesive behavior when the neutrality results from a balance of positive and negative charge carriers. Moreover, the use of net charge alone as a measure of the electrical nature of grain-to-grain relationships within a granular mass may be misleading. We believe that the dipole forces arise from the presence of randomly-distributed positive and negative fixed charge carriers on grains that give rise to a resultant dipole moment. These dipole forces have long-range attraction. Random charges are created whenever there is triboelectrical activity of a granular mass, that is, whenever the grains experience contact/separation sequences or friction. Electrostatic forces are generally under-estimated for their role in causing agglomeration of dispersed grains in particulate clouds, or their role in affecting the internal frictional relationships in packed granular masses. We believe that electrostatic, in particular dipole-mediated processes, are pervasive and probably affect, at some level, everything from astrophysical-scale granular systems such as interstellar nebulae, protoplanetary dust and debris disks, planetary-scale systems such as debris palls from meteorite impact, volcanic eruptions, and aeolian dust storms, all the way to industrial-scale systems in mining, powder and grain processing, pharmaceuticals, and smoke-stack technologies. NASA must concern itself with the electrostatic behavior of dust and sand on Mars because of its potentially critical importance to human exploration. The motion and adhesion of martian surface materials will affect the design and performance of spacesuits, habitats, processing plants, solar panels, and any externally exposed equipment such as surface rovers or communication and weather stations. Additionally, the adhesion of dust and sand could greatly enhance contact with the potentially toxic components of the martian soil.

The role of surface charge on the uptake and biocompatibility of hydroxyapatite nanoparticles with osteoblast cells

PubMed Central

Chen, Liang; Mccrate, Joseph M.; Lee, James C-M.; Li, Hao

2011-01-01

The objective of this study is to evaluate the effect of hydroxyapatite (HAP) nanoparticles with different surface charges on the cellular uptake behavior and in vitro cell viability and proliferation of MC3T3-E1 cell lines (osteoblast). The nanoparticles surface charge was varied by the surface modification with two carboxylic acids: 12-aminododecanoic acid (positive) and dodecanedioic acid (negative). The untreated HAP nanoparticles and dodecanoic acid modified HAP nanoparticles (neutral) were used as the control. X-ray diffraction (XRD) revealed that surface modifications by the three carboxylic acids did not change the crystal structure of HAP nanoparticles; Fourier transform infrared spectroscopy (FTIR) confirmed the adsorption and binding of the carboxylic acids on HAP nanoparticle surface; and zeta potential measurement confirmed that the chemicals successfully modified the surface charge of HAP nanoparticles in water based solution. Transmission electron microscopy (TEM) images showed that positively charged, negatively charged and untreated HAP nanoparticles, with similar size and shape, all penetrated into the cells and cells had more uptake of HAP nanoparticles with positive charge compared to those with negative charge, which might be attributed to the attractive or repulsive interaction between the negatively charged cell membrane and positively/negatively charged HAP nanoparticles. The neutral HAP nanoparticles could not penetrate cell membrane due to the larger size. MTT assay and LDH assay results indicated that as compared with the polystyrene control, greater cell viability and cell proliferation were measured on MC3T3-E1 cells treated with the three kinds of the HAP nanoparticles (neutral, positive, and untreated), among which positively charged HAP nanoparticles shows strongest improvement for cell viability and cell proliferation. In summary, the surface charge of HAP nanoparticles can be modified to influence the cellular uptake of HAP nanoparticles and the different uptake also influence the behavior of cells. These in-vitro results may also provide useful information for investigations of HAP nanoparticles applications in the gene delivery and intracellular drug delivery. PMID:21289408

In situ measurements and radar observations of a severe storm - Electricity, kinematics, and precipitation

NASA Technical Reports Server (NTRS)

Byrne, G. J.; Few, A. A.; Stewart, M. F.; Conrad, A. C.; Torczon, R. L.

1987-01-01

Electric field measurements made inside a multicell severe storm in Oklahoma in 1983 with a balloon-borne instrument are presented. The properties of the electric charge regions, such as altitude, thickness, and charge concentrations, are studied. These measurements are analzyed with meteorological measurements of temperature and humidity, and balloon tracking and radar observations. The relation between the electric charge structure and the precipitation and kinematic features of the storm is examined. The data reveal that the cell exhibits a bipolar charge structure with negative charge below positive charge. The average charge concentrations of the two regions are estimated as -1.2 and 0.15 nC/cu m, respectively; the upper positive charge is about 6 km in vertical extent, and the lower negative charge is less than 1 km in vertical extent.

Positively versus negatively charged moral emotion expectancies in adolescence: the role of situational context and the developing moral self.

PubMed

Krettenauer, Tobias; Johnston, Megan

2011-09-01

The study analyses adolescents' positively charged versus negatively charged moral emotion expectancies. Two hundred and five students (M= 14.83 years, SD= 2.21) participated in an interview depicting various situations in which a moral norm was either regarded or transgressed. Emotion expectancies were assessed for specific emotions (pride, guilt) as well as for overall strength and valence. In addition, self-importance of moral values was measured by a questionnaire. Results revealed that positively charged emotion expectancies were more pronounced in contexts of prosocial action than in the context of moral transgressions, whereas the opposite was true for negatively charged emotions. At the same time, expectations of guilt and pride were substantially related to the self-importance of moral values. ©2010 The British Psychological Society.

Charge rearrangement deduced from nearby electric field measurements of an intracloud flash with K‒changes

NASA Astrophysics Data System (ADS)

Hager, William W.; Feng, Wei

2013-09-01

An intracloud flash near Langmuir Laboratory is analyzed to determine the net rearrangement of charge. The analysis employed data from a balloon borne electric field sensor, or Esonde, that was within a few hundred meters of the lightning channel, data from a similar Esonde on a mountain about 6.4 km from the balloon, and data from the New Mexico Institute of Mining and Technology Lightning Mapping Array (LMA). The recovery of the charge transport required the solution of Poisson's equation over the mountainous terrain surrounding Langmuir Laboratory and the solution of a vastly under‒determined system of equations. The charge movement is analyzed using a new smooth charge transport model that incorporates constraints in the least squares fitting process through the use of penalty terms to smooth the charge movement and prevent data overfitting. The electric field measurements were consistent with about 26% of the negative charge being transported to the end of the channel, 36% deposited along the channel in the positive region, 8% deposited near the start of the channel in the positive region, and 30% deposited in another positive region several kilometers beneath the main channel. The transport of negative charge to a lower positive region occurred during the K‒processes when some negative charge was also deposited along the main channel in the upper positive region. Hence, the charge transport process during the K‒processes amounted to a tripolar charge rearrangement where the charge from the negative region was transported to two distinct positive regions, the positive region along the main channel and a lower positive region beneath the main channel. High altitude, widely scattered LMA sources beyond the end of the main channel could indicate the existence of streamers which transported the end‒of‒channel charge into the surrounding volume. Although the LMA showed the development of two upper channels, the charge transport analysis showed that measurable charge transport only occurred on one of the channels. The channel that did not transport charge was missing the high altitude, widely scattered LMA sources seen at the end of the channel that carried charge.

Label-free CMOS bio sensor with on-chip noise reduction scheme for real-time quantitative monitoring of biomolecules.

PubMed

Seong-Jin Kim; Euisik Yoon

2012-06-01

We present a label-free CMOS field-effect transistor sensing array to detect the surface potential change affected by the negative charge in DNA molecules for real-time monitoring and quantification. The proposed CMOS bio sensor includes a new sensing pixel architecture implemented with correlated double sampling for reducing offset fixed pattern noise and 1/f noise of the sensing devices. We incorporated non-surface binding detection which allows real-time continuous monitoring of DNA concentrations without immobilizing them on the sensing surface. Various concentrations of 19-bp oligonucleotides solution can be discriminated using the prototype device fabricated in 1- μm double-poly double-metal standard CMOS process. The detection limit was measured as 1.1 ng/μl with a dynamic range of 40 dB and the transient response time was measured less than 20 seconds.

Antibody localization in the glomerular basement membrane may precede in situ immune deposit formation in rat glomeruli.

PubMed

Agodoa, L Y; Gauthier, V J; Mannik, M

1985-02-01

The administration of cationized antibodies, specific to human serum albumin, into the renal artery of rats caused transient presence of IgG in glomeruli by immunofluorescence microscopy. Intravenous infusion of appropriate doses of antigen after the injection of cationized antibodies resulted in immune deposit formation in glomeruli that persisted through 96 hr. By electron microscopy, these deposits were located in the subepithelial area. The injection of large doses of antigen produced immune deposits which were present in glomeruli for only a few hours, presumably due to formation of only small-latticed immune complexes. The presented data indicate that cationic antibodies bound to the fixed negative charges of the glomerular basement membrane can interact with circulating antigen to form immune deposits in glomeruli. This mechanism may be important because anionic antigens have been shown to induce the synthesis of cationic antibodies.

Allosteric Modulation of Ca2+ flux in Ligand-gated Cation Channel (P2X4) by Actions on Lateral Portals*

PubMed Central

Samways, Damien S. K.; Khakh, Baljit S.; Egan, Terrance M.

2012-01-01

Human P2X receptors are a family of seven ATP-gated ion channels that transport Na+, K+, and Ca2+ across cell surface membranes. The P2X4 receptor is unique among family members in its sensitivity to the macrocyclic lactone, ivermectin, which allosterically modulates both ion conduction and channel gating. In this paper we show that removing the fixed negative charge of a single acidic amino acid (Glu51) in the lateral entrance to the transmembrane pore markedly attenuates the effect of ivermectin on Ca2+ current and channel gating. Ca2+ entry through P2X4 receptors is known to trigger downstream signaling pathways in microglia. Our experiments show that the lateral portals could present a novel target for drugs in the treatment of microglia-associated disease including neuropathic pain. PMID:22219189

Computational analysis of species transport and electrochemical characteristics of a MOLB-type SOFC

NASA Astrophysics Data System (ADS)

Hwang, J. J.; Chen, C. K.; Lai, D. Y.

A multi-physics model coupling electrochemical kinetics with fluid dynamics has been developed to simulate the transport phenomena in mono-block-layer built (MOLB) solid oxide fuel cells (SOFC). A typical MOLB module is composed of trapezoidal flow channels, corrugated positive electrode-electrolyte-negative electrode (PEN) plates, and planar inter-connecters. The control volume-based finite difference method is employed for calculation, which is based on the conservation of mass, momentum, energy, species, and electric charge. In the porous electrodes, the flow momentum is governed by a Darcy model with constant porosity and permeability. The diffusion of reactants follows the Bruggman model. The chemistry within the plates is described via surface reactions with a fixed surface-to-volume ratio, tortuosity and average pore size. Species transports as well as the local variations of electrochemical characteristics, such as overpotential and current density distributions in the electrodes of an MOLB SOFC, are discussed in detail.

Characteristic study of head-on collision of dust-ion acoustic solitons of opposite polarity with kappa distributed electrons

NASA Astrophysics Data System (ADS)

Parveen, Shahida; Mahmood, Shahzad; Adnan, Muhammad; Qamar, Anisa

2016-09-01

The head on collision between two dust ion acoustic (DIA) solitary waves, propagating in opposite directions, is studied in an unmagnetized plasma constituting adiabatic ions, static dust charged (positively/negatively) grains, and non-inertial kappa distributed electrons. In the linear limit, the dispersion relation of the dust ion acoustic (DIA) solitary wave is obtained using the Fourier analysis. For studying characteristic head-on collision of DIA solitons, the extended Poincaré-Lighthill-Kuo method is employed to obtain Korteweg-de Vries (KdV) equations with quadratic nonlinearities and investigated the phase shifts in their trajectories after the interaction. It is revealed that only compressive solitary waves can exist for the positive dust charged concentrations while for negative dust charge concentrations both the compressive and rarefactive solitons can propagate in such dusty plasma. It is found that for specific sets of plasma parameters, the coefficient of nonlinearity disappears in the KdV equation for the negative dust charged grains. Therefore, the modified Korteweg-de Vries (mKdV) equations with cubic nonlinearity coefficient, and their corresponding phase shift and trajectories, are also derived for negative dust charged grains plasma at critical composition. The effects of different plasma parameters such as superthermality, concentration of positively/negatively static dust charged grains, and ion to electron temperature ratio on the colliding soliton profiles and their corresponding phase shifts are parametrically examined.

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

Wu, Kaifeng; Lim, Jaehoon; Klimov, Victor I.

Application of colloidal semiconductor quantum dots (QDs) in optical and optoelectronic devices is often complicated by unintentional generation of extra charges, which opens fast nonradiative Auger recombination pathways whereby the recombination energy of an exciton is quickly transferred to the extra carrier(s) and ultimately dissipated as heat. Previous studies of Auger recombination have primarily focused on neutral and, more recently, negatively charged multicarrier states. Auger dynamics of positively charged species remains more poorly explored due to difficulties in creating, stabilizing, and detecting excess holes in the QDs. Here we apply photochemical doping to prepare both negatively and positively charged CdSe/CdSmore » QDs with two distinct core/shell interfacial profiles (“sharp” versus “smooth”). Using neutral and charged QD samples we evaluate Auger lifetimes of biexcitons, negative and positive trions (an exciton with an extra electron or a hole, respectively), and multiply negatively charged excitons. Using these measurements, we demonstrate that Auger decay of both neutral and charged multicarrier states can be presented as a superposition of independent elementary three-particle Auger events. As one of the manifestations of the superposition principle, we observe that the biexciton Auger decay rate can be presented as a sum of the Auger rates for independent negative and positive trion pathways. Furthermore, by comparing the measurements on the QDs with the “sharp” versus “smooth” interfaces, we also find that while affecting the absolute values of Auger lifetimes, manipulation of the shape of the confinement potential does not lead to violation of the superposition principle, which still allows us to accurately predict the biexciton Auger lifetimes based on the measured negative and positive trion dynamics. Our findings indicate considerable robustness of the superposition principle as applied to Auger decay of charged and neutral multicarrier states, suggesting its generality to quantum-confined nanocrystals of arbitrary compositions and complexities.« less

Electrical charging effects on the sliding friction of a model nano-confined ionic liquid

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

Capozza, R.; Vanossi, A.; CNR-IOM Democritos National Simulation Center, Via Bonomea 265, 34136 Trieste

2015-10-14

Recent measurements suggest the possibility to exploit ionic liquids (ILs) as smart lubricants for nano-contacts, tuning their tribological and rheological properties by charging the sliding interfaces. Following our earlier theoretical study of charging effects on nanoscale confinement and squeezout of a model IL, we present here molecular dynamics simulations of the frictional and lubrication properties of that model under charging conditions. First, we describe the case when two equally charged plates slide while being held together to a confinement distance of a few molecular layers. The shear sliding stress is found to rise strongly and discontinuously as the number ofmore » IL layers decreases stepwise. However, the shear stress shows, within each given number of layers, only a weak dependence upon the precise value of the normal load, a result in agreement with data extracted from recent experiments. We subsequently describe the case of opposite charging of the sliding plates and follow the shear stress when the charging is slowly and adiabatically reversed in the course of time, under fixed load. Despite the fixed load, the number and structure of the confined IL layers change with changing charge, and that in turn drives strong friction variations. The latter involves first of all charging-induced freezing of the IL film, followed by a discharging-induced melting, both made possible by the nanoscale confinement. Another mechanism for charging-induced frictional changes is a shift of the plane of maximum shear from mid-film to the plate-film interface, and vice versa. While these occurrences and results invariably depend upon the parameters of the model IL and upon its specific interaction with the plates, the present study helps identifying a variety of possible behavior, obtained under very simple assumptions, while connecting it to an underlying equilibrium thermodynamics picture.« less

A Unified Model of Cloud-to-Ground Lightning Stroke

NASA Astrophysics Data System (ADS)

Nag, A.; Rakov, V. A.

2014-12-01

The first stroke in a cloud-to-ground lightning discharge is thought to follow (or be initiated by) the preliminary breakdown process which often produces a train of relatively large microsecond-scale electric field pulses. This process is poorly understood and rarely modeled. Each lightning stroke is composed of a downward leader process and an upward return-stroke process, which are usually modeled separately. We present a unified engineering model for computing the electric field produced by a sequence of preliminary breakdown, stepped leader, and return stroke processes, serving to transport negative charge to ground. We assume that a negatively-charged channel extends downward in a stepped fashion through the relatively-high-field region between the main negative and lower positive charge centers and then through the relatively-low-field region below the lower positive charge center. A relatively-high-field region is also assumed to exist near ground. The preliminary breakdown pulse train is assumed to be generated when the negatively-charged channel interacts with the lower positive charge region. At each step, an equivalent current source is activated at the lower extremity of the channel, resulting in a step current wave that propagates upward along the channel. The leader deposits net negative charge onto the channel. Once the stepped leader attaches to ground (upward connecting leader is presently neglected), an upward-propagating return stroke is initiated, which neutralizes the charge deposited by the leader along the channel. We examine the effect of various model parameters, such as step length and current propagation speed, on model-predicted electric fields. We also compare the computed fields with pertinent measurements available in the literature.

Carbon nanotubes' surface chemistry determines their potency as vaccine nanocarriers in vitro and in vivo

PubMed Central

Hassan, Hatem A.F.M.; Smyth, Lesley; Rubio, Noelia; Ratnasothy, Kulachelvy; Wang, Julie T.-W.; Bansal, Sukhvinder S.; Summers, Huw D.; Diebold, Sandra S.; Lombardi, Giovanna; Al-Jamal, Khuloud T.

2016-01-01

Carbon nanotubes (CNTs) have shown marked capabilities in enhancing antigen delivery to antigen presenting cells. However, proper understanding of how altering the physical properties of CNTs may influence antigen uptake by antigen presenting cells, such as dendritic cells (DCs), has not been established yet. We hypothesized that altering the physical properties of multi-walled CNTs (MWNTs)-antigen conjugates, e.g. length and surface charge, can affect the internalization of MWNT-antigen by DCs, hence the induced immune response potency. For this purpose, pristine MWNTs (p-MWNTs) were exposed to various chemical reactions to modify their physical properties then conjugated to ovalbumin (OVA), a model antigen. The yielded MWNTs-OVA conjugates were long MWNT-OVA (~ 386 nm), bearing net positive charge (5.8 mV), or short MWNTs-OVA (~ 122 nm) of increasing negative charges (− 23.4, − 35.8 or − 39 mV). Compared to the short MWNTs-OVA bearing high negative charges, short MWNT-OVA with the lowest negative charge demonstrated better cellular uptake and OVA-specific immune response both in vitro and in vivo. However, long positively-charged MWNT-OVA showed limited cellular uptake and OVA specific immune response in contrast to short MWNT-OVA displaying the least negative charge. We suggest that reduction in charge negativity of MWNT-antigen conjugate enhances cellular uptake and thus the elicited immune response intensity. Nevertheless, length of MWNT-antigen conjugate might also affect the cellular uptake and immune response potency; highlighting the importance of physical properties as a consideration in designing a MWNT-based vaccine delivery system. PMID:26802552

Interactions of microbicide nanoparticles with a simulated vaginal fluid.

PubMed

das Neves, José; Rocha, Cristina M R; Gonçalves, Maria Pilar; Carrier, Rebecca L; Amiji, Mansoor; Bahia, Maria Fernanda; Sarmento, Bruno

2012-11-05

The interaction with cervicovaginal mucus presents the potential to impact the performance of drug nanocarriers. These systems must migrate through this biological fluid in order to deliver their drug payload to the underlying mucosal surface. We studied the ability of dapivirine-loaded polycaprolactone (PCL)-based nanoparticles (NPs) to interact with a simulated vaginal fluid (SVF) incorporating mucin. Different surface modifiers were used to produce NPs with either negative (poloxamer 338 NF and sodium lauryl sulfate) or positive (cetyltrimethylammonium bromide) surface charge. Studies were performed using the mucin particle method, rheological measurements, and real-time multiple particle tracking. Results showed that SVF presented rheological properties similar to those of human cervicovaginal mucus. Analysis of NP transport indicated mild interactions with mucin and low adhesive potential. In general, negatively charged NPs underwent subdiffusive transport in SVF, i.e., hindered as compared to their diffusion in water, but faster than for positively charged NPs. These differences were increased when the pH of SVF was changed from 4.2 to 7.0. Diffusivity was 50- and 172-fold lower in SVF at pH 4.2 than in water for negatively charged and positively charged NPs, respectively. At pH 7.0, this decrease was around 20- and 385-fold, respectively. The estimated times required to cross a layer of SVF were equal to or lower than 1.7 h for negatively charged NPs, while for positively charged NPs these values were equal to or higher than 7 h. Overall, our results suggest that negatively charged PCL NPs may be suitable to be used as carriers in order to deliver dapivirine and potentially other antiretroviral drugs to the cervicovaginal mucosal lining. Also, they further reinforce the importance in characterizing the interactions of nanosystems with mucus fluids or surrogates when considering mucosal drug delivery.

Intracellular sorting of differently charged chitosan derivatives and chitosan-based nanoparticles

NASA Astrophysics Data System (ADS)

Zubareva, A. A.; Shcherbinina, T. S.; Varlamov, V. P.; Svirshchevskaya, E. V.

2015-04-01

Chitosan (Chi) is a biodegradable nontoxic polycation with multiple reactive groups that is easily used to obtain derivatives with a desired charge and hydrophobic properties. The aim of this work was to study the intracellular traffic of positively charged hexanoyl-chitosan (HC) or HC-based nanoparticles (HCNPs) and negatively charged succinoyl-chitosan (SC) and SCNPs in epithelial and macrophage cell lines. By using flow cytometry we demonstrated that positively charged HC adhered to cell membranes quicker and more efficiently than negatively charged SC or NPs. However confocal studies showed that SC and SCNPs penetrated cells much more efficiently than HC while HCNPs did not enter the epithelial cells. Macrophages also phagocyted better negatively charged material but were able to engulf both HC and HCNPs. Upon entering the cells, SC and SCNPs were co-localized with endosomes and lysosomes while HC was found in mitochondria and, to a lesser extent, in lysosomes of epithelial cells. Macrophages, RAW264.7, more efficiently transported all Chi samples to the lysosomal compartment while some positively charged material was still found in mitochondria. Incubation of Chi derivatives and ChiNPs at pH specific to mitochondria (8.0) and lysosomes (4.5) demonstrated the neutralization of Chi charge. We concluded that epithelial cells and, to a lesser extent, macrophages sort charged material to the organelles neutralizing Chi charge.

Detecting negative ions on board small satellites

NASA Astrophysics Data System (ADS)

Lepri, S. T.; Raines, J. M.; Gilbert, J. A.; Cutler, J.; Panning, M.; Zurbuchen, T. H.

2017-04-01

Recent measurements near comets, planets, and their satellites have shown that heavy ions, energetic neutral atoms, molecular ions, and charged dust contain a wealth of information about the origin, evolution, and interaction of celestial bodies with their space environment. Using highly sensitive plasma instruments, positively charged heavy ions have been used to trace exospheric and surface composition of comets, planets, and satellites as well as the composition of interplanetary and interstellar dust. While positive ions dominate throughout the heliosphere, negative ions are also produced from surface interactions. In fact, laboratory experiments have shown that oxygen released from rocky surfaces is mostly negatively charged. Negative ions and negatively charged nanograins have been detected with plasma electron analyzers in several different environments (e.g., by Cassini and Rosetta), though more extensive studies have been challenging without instrumentation dedicated to negative ions. We discuss an adaptation of the Fast Imaging Plasma Spectrometer (FIPS) flown on MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) for the measurement of negatively charged particles. MESSENGER/FIPS successfully measured the plasma environment of Mercury from 2011 until 2015, when the mission ended, and has been used to map multiple ion species (H+ through Na+ and beyond) throughout Mercury's space environment. Modifications to the existing instrument design fits within a 3U CubeSat volume and would provide a low mass, low power instrument, ideal for future CubeSat or distributed sensor missions seeking, for the first time, to characterize the contribution of negative particles in the heliospheric plasmas near the planets, moons, comets, and other sources.

Modulating the line shape of magnetoconductance by varying the charge injection in polymer light-emitting diodes

NASA Astrophysics Data System (ADS)

Chitraningrum, Nidya; Chu, Ting-Yi; Huang, Ping-Tsung; Wen, Ten-Chin; Guo, Tzung-Fang

2018-02-01

We fabricate the phenyl-substituted poly(p-phenylene vinylene) copolymer (super yellow, SY-PPV)-based polymer light-emitting diodes (PLEDs) with different device architectures to modulate the injection of opposite charge carriers and investigate the corresponding magnetoconductance (MC) responses. At the first glance, we find that all PLEDs exhibit the positive MC responses. By applying the mathematical analysis to fit the curves with two empirical equations of a non-Lorentzian and a Lorentzian function, we are able to extract the hidden negative MC component from the positive MC curve. We attribute the growth of the negative MC component to the reduced interaction of the triplet excitons with charges to generate the free charge carriers as modulated by the applied magnetic field, known as the triplet exciton-charge reaction, by analyzing MC responses for PLEDs of the charge-unbalanced and hole-blocking device configurations. The negative MC component causes the broadening of the line shape in MC curves.

Impact of wearing fixed orthodontic appliances on quality of life among adolescents: Case-control study.

PubMed

Costa, Andréa A; Serra-Negra, Júnia M; Bendo, Cristiane B; Pordeus, Isabela A; Paiva, Saul M

2016-01-01

To investigate the impact of wearing a fixed orthodontic appliance on oral health-related quality of life (OHRQoL) among adolescents. A case-control study (1 ∶ 2) was carried out with a population-based randomized sample of 327 adolescents aged 11 to 14 years enrolled at public and private schools in the City of Brumadinho, southeast of Brazil. The case group (n  =  109) was made up of adolescents with a high negative impact on OHRQoL, and the control group (n  =  218) was made up of adolescents with a low negative impact. The outcome variable was the impact on OHRQoL measured by the Brazilian version of the Child Perceptions Questionnaire (CPQ 11-14) - Impact Short Form (ISF:16). The main independent variable was wearing fixed orthodontic appliances. Malocclusion and the type of school were identified as possible confounding variables. Bivariate and multiple conditional logistic regressions were employed in the statistical analysis. A multiple conditional logistic regression model demonstrated that adolescents wearing fixed orthodontic appliances had a 4.88-fold greater chance of presenting high negative impact on OHRQoL (95% CI: 2.93-8.13; P < .001) than those who did not wear fixed orthodontic appliances. A bivariate conditional logistic regression demonstrated that malocclusion was significantly associated with OHRQoL (P  =  .017), whereas no statistically significant association was found between the type of school and OHRQoL (P  =  .108). Adolescents who wore fixed orthodontic appliances had a greater chance of reporting a negative impact on OHRQoL than those who did not wear such appliances.

Explicit construction of BRST charge of noncommutative D-brane system

NASA Astrophysics Data System (ADS)

Hong, Soon-Tae

2006-01-01

In the BRST BFV scheme for noncommutative D-branes with constant NS B-field, introducing ghost degrees of freedom we construct the gauge-fixed Hamiltonian and corresponding effective Lagrangian invariant under nilpotent BRST charge. It is also shown that the presence of auxiliary variables introduced via the improved Dirac formalism plays a crucial role in the construction of the BRST invariant Lagrangian.

Singularity-free solutions for anisotropic charged fluids with Chaplygin equation of state

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

Rahaman, Farook; Ray, Saibal; Jafry, Abdul Kayum

2010-11-15

We extend the Krori-Barua analysis of the static, spherically symmetric, Einstein-Maxwell field equations and consider charged fluid sources with anisotropic stresses. The inclusion of a new variable (tangential pressure) allows the use of a nonlinear, Chaplygin-type equation of state with coefficients fixed by the matching conditions at the boundary of the source. Some physical features are briefly discussed.

Negative charge emission due to excimer laser bombardment of sodium trisilicate glass

NASA Astrophysics Data System (ADS)

Langford, S. C.; Jensen, L. C.; Dickinson, J. T.; Pederson, L. R.

1990-10-01

We describe measurements of negative charge emission accompanying irradiation of sodium trisilicate glass (Na2Oṡ3SiO2) with 248-nm excimer laser light at fluences on the order of 2 J/cm2 per pulse, i.e., at the threshold for ablative etching of the glass surface. The negative charge emission consists of a very prompt photoelectron burst coincident with the laser pulse, followed by a much slower plume of electrons and negative ions traveling with a high density cloud of positive ions, previously identified as primarily Na+. Using combinations of E and B fields in conjunction with time-of-flight methods, the negative ions were successfully separated from the plume and tentatively identified as O-, Si-, NaO-, and perhaps NaSi-. These negative species are probably formed by gas phase collisions in the near-surface region which result in electron attachment.

Negatively Charged Lipid Membranes Promote a Disorder-Order Transition in the Yersinia YscU Protein

PubMed Central

Weise, Christoph F.; Login, Frédéric H.; Ho, Oanh; Gröbner, Gerhard; Wolf-Watz, Hans; Wolf-Watz, Magnus

2014-01-01

The inner membrane of Gram-negative bacteria is negatively charged, rendering positively charged cytoplasmic proteins in close proximity likely candidates for protein-membrane interactions. YscU is a Yersinia pseudotuberculosis type III secretion system protein crucial for bacterial pathogenesis. The protein contains a highly conserved positively charged linker sequence that separates membrane-spanning and cytoplasmic (YscUC) domains. Although disordered in solution, inspection of the primary sequence of the linker reveals that positively charged residues are separated with a typical helical periodicity. Here, we demonstrate that the linker sequence of YscU undergoes a largely electrostatically driven coil-to-helix transition upon binding to negatively charged membrane interfaces. Using membrane-mimicking sodium dodecyl sulfate micelles, an NMR derived structural model reveals the induction of three helical segments in the linker. The overall linker placement in sodium dodecyl sulfate micelles was identified by NMR experiments including paramagnetic relaxation enhancements. Partitioning of individual residues agrees with their hydrophobicity and supports an interfacial positioning of the helices. Replacement of positively charged linker residues with alanine resulted in YscUC variants displaying attenuated membrane-binding affinities, suggesting that the membrane interaction depends on positive charges within the linker. In vivo experiments with bacteria expressing these YscU replacements resulted in phenotypes displaying significantly reduced effector protein secretion levels. Taken together, our data identify a previously unknown membrane-interacting surface of YscUC that, when perturbed by mutations, disrupts the function of the pathogenic machinery in Yersinia. PMID:25418176

Negatively charged lipid membranes promote a disorder-order transition in the Yersinia YscU protein.

PubMed

Weise, Christoph F; Login, Frédéric H; Ho, Oanh; Gröbner, Gerhard; Wolf-Watz, Hans; Wolf-Watz, Magnus

2014-10-21

The inner membrane of Gram-negative bacteria is negatively charged, rendering positively charged cytoplasmic proteins in close proximity likely candidates for protein-membrane interactions. YscU is a Yersinia pseudotuberculosis type III secretion system protein crucial for bacterial pathogenesis. The protein contains a highly conserved positively charged linker sequence that separates membrane-spanning and cytoplasmic (YscUC) domains. Although disordered in solution, inspection of the primary sequence of the linker reveals that positively charged residues are separated with a typical helical periodicity. Here, we demonstrate that the linker sequence of YscU undergoes a largely electrostatically driven coil-to-helix transition upon binding to negatively charged membrane interfaces. Using membrane-mimicking sodium dodecyl sulfate micelles, an NMR derived structural model reveals the induction of three helical segments in the linker. The overall linker placement in sodium dodecyl sulfate micelles was identified by NMR experiments including paramagnetic relaxation enhancements. Partitioning of individual residues agrees with their hydrophobicity and supports an interfacial positioning of the helices. Replacement of positively charged linker residues with alanine resulted in YscUC variants displaying attenuated membrane-binding affinities, suggesting that the membrane interaction depends on positive charges within the linker. In vivo experiments with bacteria expressing these YscU replacements resulted in phenotypes displaying significantly reduced effector protein secretion levels. Taken together, our data identify a previously unknown membrane-interacting surface of YscUC that, when perturbed by mutations, disrupts the function of the pathogenic machinery in Yersinia.

Interacting charges and the classical electron radius

NASA Astrophysics Data System (ADS)

De Luca, Roberto; Di Mauro, Marco; Faella, Orazio; Naddeo, Adele

2018-03-01

The equation of the motion of a point charge q repelled by a fixed point-like charge Q is derived and studied. In solving this problem useful concepts in classical and relativistic kinematics, in Newtonian mechanics and in non-linear ordinary differential equations are revised. The validity of the approximations is discussed from the physical point of view. In particular the classical electron radius emerges naturally from the requirement that the initial distance is large enough for the non-relativistic approximation to be valid. The relevance of this topic for undergraduate physics teaching is pointed out.

Triboelectric energy harvesting with surface-charge-fixed polymer based on ionic liquid

PubMed Central

Sano, Chikako; Mitsuya, Hiroyuki; Ono, Shimpei; Miwa, Kazumoto; Toshiyoshi, Hiroshi; Fujita, Hiroyuki

2018-01-01

Abstract A novel triboelectric energy harvester has been developed using an ionic liquid polymer with cations fixed at the surface. In this report, the fabrication of the device and the characterization of its energy harvesting performance are detailed. An electrical double layer was induced in the ionic liquid polymer precursor to attract the cations to the surface where they are immobilized using a UV-based crosslinking reaction. The finalized polymer is capable of generating an electrical current when contacted by a metal electrode. Using this property, energy harvesting experiments were conducted by cyclically contacting a gold-surface electrode with the charge fixed surface of the polymer. Control experiments verified the effect of immobilizing the cations at the surface. By synthesizing a polymer with the optimal composition ratio of ionic liquid to macromonomer, an output of 77 nW/cm2 was obtained with a load resistance of 1 MΩ at 1 Hz. This tuneable power supply with a μA level current output may contribute to Internet of Things networks requiring numerous sensor nodes at remote places in the environment. PMID:29707070

Protein Charge and Mass Contribute to the Spatio-temporal Dynamics of Protein-Protein Interactions in a Minimal Proteome

PubMed Central

Xu, Yu; Wang, Hong; Nussinov, Ruth; Ma, Buyong

2013-01-01

We constructed and simulated a ‘minimal proteome’ model using Langevin dynamics. It contains 206 essential protein types which were compiled from the literature. For comparison, we generated six proteomes with randomized concentrations. We found that the net charges and molecular weights of the proteins in the minimal genome are not random. The net charge of a protein decreases linearly with molecular weight, with small proteins being mostly positively charged and large proteins negatively charged. The protein copy numbers in the minimal genome have the tendency to maximize the number of protein-protein interactions in the network. Negatively charged proteins which tend to have larger sizes can provide large collision cross-section allowing them to interact with other proteins; on the other hand, the smaller positively charged proteins could have higher diffusion speed and are more likely to collide with other proteins. Proteomes with random charge/mass populations form less stable clusters than those with experimental protein copy numbers. Our study suggests that ‘proper’ populations of negatively and positively charged proteins are important for maintaining a protein-protein interaction network in a proteome. It is interesting to note that the minimal genome model based on the charge and mass of E. Coli may have a larger protein-protein interaction network than that based on the lower organism M. pneumoniae. PMID:23420643

An analytic expression for the sheath criterion in magnetized plasmas with multi-charged ion species

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

Hatami, M. M., E-mail: m-hatami@kntu.ac.ir

2015-04-15

The generalized Bohm criterion in magnetized multi-component plasmas consisting of multi-charged positive and negative ion species and electrons is analytically investigated by using the hydrodynamic model. It is assumed that the electrons and negative ion density distributions are the Boltzmann distribution with different temperatures and the positive ions enter into the sheath region obliquely. Our results show that the positive and negative ion temperatures, the orientation of the applied magnetic field and the charge number of positive and negative ions strongly affect the Bohm criterion in these multi-component plasmas. To determine the validity of our derived generalized Bohm criterion, itmore » reduced to some familiar physical condition and it is shown that monotonically reduction of the positive ion density distribution leading to the sheath formation occurs only when entrance velocity of ion into the sheath satisfies the obtained Bohm criterion. Also, as a practical application of the obtained Bohm criterion, effects of the ionic temperature and concentration as well as magnetic field on the behavior of the charged particle density distributions and so the sheath thickness of a magnetized plasma consisting of electrons and singly charged positive and negative ion species are studied numerically.« less

The Transport of Salt and Water across Isolated Rat Ileum

PubMed Central

Clarkson, T. W.

1967-01-01

The flows of sodium, potassium, and chloride under electrical and chemical gradients and of salt and water in the presence of osmotic pressure gradients are described by phenomenological equations based on the thermodynamics of irreversible processes. The aim was to give the simplest possible description, that is to postulate the least number of active transport processes and the least number of separate pathways across the intestine. On this basis, the results were consistent with the following picture of the intestine: Two channels exist across this tissue, one allowing only passive transport of ions and the other only active. In the passive channel, the predominant resistance to ion flow is friction with the water in the channel. The electroosmotic flow indicates that the passive channel is lined with negative fixed charged groups having a surface charge density of 3000 esu cm-2. The values of the ion-water frictional coefficients, and the relationship between ionic concentrations and flows indicate that the passive channel is extracellular. The active channel behaves as two membranes in series, the first membrane being semipermeable but allowing active transport of sodium, and the second membrane being similar to the passive channel. Friction with the ions in the second "membrane" is the predominant resistance to water flow. PMID:11526854

Influence of CO annealing in metal-oxide-semiconductor capacitors with SiO2 films thermally grown on Si and on SiC

NASA Astrophysics Data System (ADS)

Pitthan, E.; dos Reis, R.; Corrêa, S. A.; Schmeisser, D.; Boudinov, H. I.; Stedile, F. C.

2016-01-01

Understanding the influence of SiC reaction with CO, a by-product of SiC thermal oxidation, is a key point to elucidate the origin of electrical defects in SiC metal-oxide-semiconductor (MOS) devices. In this work, the effects on electrical, structural, and chemical properties of SiO2/Si and SiO2/SiC structures submitted to CO annealing were investigated. It was observed that long annealing times resulted in the incorporation of carbon from CO in the Si substrate, followed by deterioration of the SiO2/Si interface, and its crystallization as SiC. Besides, this incorporated carbon remained in the Si surface (previous SiO2/Si region) after removal of the silicon dioxide film by HF etching. In the SiC case, an even more defective surface region was observed due to the CO interaction. All MOS capacitors formed using both semiconductor materials presented higher leakage current and generation of positive effective charge after CO annealings. Such results suggest that the negative fixed charge, typically observed in SiO2/SiC structures, is not originated from the interaction of the CO by-product, formed during SiC oxidation, with the SiO2/SiC interfacial region.

Electrical detection of the biological interaction of a charged peptide via gallium arsenide junction-field-effect transistors

PubMed Central

Lee, Kangho; Nair, Pradeep R.; Alam, Muhammad A.; Janes, David B.; Wampler, Heeyeon P.; Zemlyanov, Dmitry Y.; Ivanisevic, Albena

2008-01-01

GaAs junction-field-effect transistors (JFETs) are utilized to achieve label-free detection of biological interaction between a probe transactivating transcriptional activator (TAT) peptide and the target trans-activation-responsive (TAR) RNA. The TAT peptide is a short sequence derived from the human immunodeficiency virus-type 1 TAT protein. The GaAs JFETs are modified with a mixed adlayer of 1-octadecanethiol (ODT) and TAT peptide, with the ODT passivating the GaAs surface from polar ions in physiological solutions and the TAT peptide providing selective binding sites for TAR RNA. The devices modified with the mixed adlayer exhibit a negative pinch-off voltage (VP) shift, which is attributed to the fixed positive charges from the arginine-rich regions in the TAT peptide. Immersing the modified devices into a TAR RNA solution results in a large positive VP shift (>1 V) and a steeper subthreshold slope (∼80 mV∕decade), whereas “dummy” RNA induced a small positive VP shift (∼0.3 V) without a significant change in subthreshold slopes (∼330 mV∕decade). The observed modulation of device characteristics is analyzed with analytical modeling and two-dimensional numerical device simulations to investigate the electronic interactions between the GaAs JFETs and biological molecules. PMID:19484151

Fractionation and characterization of natural organic matter from certain rivers and soils by free-flow electrophoresis

USGS Publications Warehouse

Leenheer, J.A.; Malcolm, R.L.

1973-01-01

Soluble river organic matter and soil fulvic acids from a variety of environments were compared by examining the free-flow electrophoretic fractionation curves of organic carbon, color, and polysaccharides. Significant amounts of virtually colorless organic material were found in both the soil and the river preparations. Polysaccharides comprised 20-75 percent of the colorless material in the soil fulvic acids but only 3.2-7.0 percent of the colorless material in the river preparations. A significant amount of polysaccharides was complexed with organic materials having negative charges. Amounts of polysaccharides were greater in the Fairbanks soil from Alaska than in the soils from North Carolina or Iowa, and they were greater in the Tahquamenon River in Michigan than in the two rivers in Florida; this suggests that polysaccharide degradation is slower in cooler environments. For all of the organic preparations which were fractionated, the intensity of the yellow color increased as the charge on the organic anion increased. Highly colored, negatively charged organic material was found to be present in greater amounts in the subsurface spodic soil horizon of the Lakewood and Fairbanks soils than in the surface mollic horizon of the Macksburg soil. Infrared spectroscopy and elemental analysis of four pooled fractions of the Fairbanks fulvic acid indicated increasing aromatic character with increasing negative charge. An increase in the carboxyl content with negative charge suggests the carboxyl group as the primary source of the negative charge.

Cationic cell-penetrating peptide binds to planar lipid bilayers containing negatively charged lipids but does not induce conductive pores.

PubMed

Gurnev, Philip A; Yang, Sung-Tae; Melikov, Kamran C; Chernomordik, Leonid V; Bezrukov, Sergey M

2013-05-07

Using a cation-selective gramicidin A channel as a sensor of the membrane surface charge, we studied interactions of oligoarginine peptide R9C, a prototype cationic cell-penetrating peptide (CPP), with planar lipid membranes. We have found that R9C sorption to the membrane depends strongly on its lipid composition from virtually nonexistent for membranes made of uncharged lipids to very pronounced for membranes containing negatively charged lipids, with charge overcompensation at R9C concentrations exceeding 1 μM. The sorption was reversible as it was removed by addition of polyanionic dextran sulfate to the membrane bathing solution. No membrane poration activity of R9C (as would be manifested by increased bilayer conductance) was detected in the charged or neutral membranes, including those with asymmetric negative/neutral and negative/positive lipid leaflets. We conclude that interaction of R9C with planar lipid bilayers does not involve pore formation in all studied lipid combinations up to 20 μM peptide concentration. However, R9C induces leakage of negatively charged but not neutral liposomes in a process that involves lipid mixing between liposomes. Our findings suggest that direct traversing of CPPs through the uncharged outer leaflet of the plasma membrane bilayer is unlikely and that permeabilization necessarily involves both anionic lipids and CPP-dependent fusion between opposing membranes. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Closed-loop pulsed helium ionization detector

DOEpatents

Ramsey, Roswitha S.; Todd, Richard A.

1987-01-01

A helium ionization detector for gas chromatography is operated in a constant current, pulse-modulated mode by configuring the detector, electrometer and a high voltage pulser in a closed-loop control system. The detector current is maintained at a fixed level by varying the frequency of fixed-width, high-voltage bias pulses applied to the detector. An output signal proportional to the pulse frequency is produced which is indicative of the charge collected for a detected species.

Masking functions and fixed-signal functions for low-level 1000-Hz tones.

PubMed

Shepherd, Daniel; Hautus, Michael J; Jesteadt, Walt

2013-06-01

Masking functions and fixed-signal functions were constructed using a narrow range of pedestal intensities for 10-ms, 1000-Hz gated tones. Data from three experiments agreed with previously reported data, clearly demonstrating negative masking and the pedestal effect. The data extend earlier findings by showing (1) the resilience of the pedestal effect when a background noise masker is introduced; (2) a possible indifference of the fixed-signal function to stimulus duration; (3) the ability of a set of psychometric functions to produce both masking and fixed-signal functions; (4) depending on method, the impact of unit choice on the interpretation of both the pedestal effect and negative masking data. Results are discussed in relation to current psychophysical models, and suggest that accounting for the auditory system's sensitivity to differences in low-level sounds remains a challenge.

Bacterial attachment to RO membranes surface-modified by concentration-polarization-enhanced graft polymerization.

PubMed

Bernstein, Roy; Belfer, Sofia; Freger, Viatcheslav

2011-07-15

Concentration polarization-enhanced radical graft polymerization, a facile surface modification technique, was examined as an approach to reduce bacterial deposition onto RO membranes and thus contribute to mitigation of biofouling. For this purpose an RO membrane ESPA-1 was surface-grafted with a zwitterionic and negatively and positively charged monomers. The low monomer concentrations and low degrees of grafting employed in modifications moderately reduced flux (by 20-40%) and did not affect salt rejection, yet produced substantial changes in surface chemistry, charge and hydrophilicity. The propensity to bacterial attachment of original and modified membranes was assessed using bacterial deposition tests carried out in a parallel plate flow setup using a fluorescent strain of Pseudomonas fluorescens. Compared to unmodified ESPA-1 the deposition (mass transfer) coefficient was significantly increased for modification with the positively charged monomer. On the other hand, a substantial reduction in bacterial deposition rates was observed for membranes modified with zwitterionic monomer and, still more, with very hydrophilic negatively charged monomers. This trend is well explained by the effects of surface charge (as measured by ζ-potential) and hydrophilicity (contact angle). It also well correlated with force distance measurements by AFM using surrogate spherical probes with a negative surface charge mimicking the bacterial surface. The positively charged surface showed a strong hysteresis with a large adhesion force, which was weaker for unmodified ESPA-1 and still weaker for zwitterionic surface, while negatively charged surface showed a long-range repulsion and negligible hysteresis. These results demonstrate the potential of using the proposed surface- modification approach for varying surface characteristics, charge and hydrophilicity, and thus minimizing bacterial deposition and potentially reducing propensity biofouling.

Traps and Interface Fixed Charge Effects on a Solution-Processed n-Type Polymeric-Based Organic Field-Effect Transistor

NASA Astrophysics Data System (ADS)

Hafsi, B.; Boubaker, A.; Guerin, D.; Lenfant, S.; Kalboussi, A.; Lmimouni, K.

2017-02-01

Organic field-effect transistors based on poly{[ N, N0- bis(2-octyldodecyl)- naphthalene-1,4,5,8- bis(dicarboximide)-2,6-diyl]-alt-5,50-(2,20-bithiophene)}, [P(NDI2OD-T2)n], were fabricated and characterized. The effect of octadecyltrichlorosilane (OTS) a self-assembled monolayer (SAM) grafted on to a SiO2 gate dielectric was investigated. A significant improvement of the charge mobility ( μ), up to 0.22 cm2/V s, was reached thanks to the OTS treatment. Modifying some technological parameters relating to fabrication, such as solvents, was also studied. We have analyzed the electrical properties of these thin-film transistors by using a two-dimensional drift-diffusion simulator, Integrated System Engineering-Technology Computer Aided Design (ISE-TCAD®). We studied the fixed surface charges at the organic semiconductor/oxide interface and the bulk traps effect. The dependence of the threshold voltage on the density and energy level of the trap states has also been considered. We finally found a good agreement between the output and transfer characteristics for experimental and simulated data.

Concurrent application of charge using a novel circuit prevents heat-related coagulum formation during radiofrequency ablation.

PubMed

Lim, Bernard; Venkatachalam, Kalpathi L; Jahangir, Arshad; Johnson, Susan B; Asirvatham, Samuel J

2008-08-01

Thromboembolism resulting from coagulum formation on the catheter and electrode surfaces is a serious complication with radiofrequency ablation procedures for heart rhythm disorders. Why coagulum occurs despite therapeutic heparinization is unclear. In this report, we demonstrate a novel approach to minimize coagulum formation based on the electromolecular characteristics of fibrinogen. Atomic force microscopy was used to establish that fibrinogen deposited on surfaces underwent conformational changes that resulted in spontaneous clot formation. We then immersed ablation catheters that were uncharged, negatively, or positively charged in heparinized blood for 30 minutes and noted the extent of clot formation. In separate experiments, ablation catheters were sutured to the ventricle of an excised porcine heart immersed in whole, heparinized blood and radiofrequency ablation performed for 5 minutes with and without charge delivered to the catheter tips. Electron microscopy of the catheter tips showed surface coverage of fibrin clot of the catheter to be 33.8% for negatively charged catheters, compared with 84.7% (P = 0.01) in noncharged catheters. There was no significant difference in surface coverage of fibrin clot between positively charged catheters (93.8%) and noncharged catheters (84.7%, P = ns). In contrast, the thickness of surface clot coverage for positively charged catheters was 87.5%, compared with 28.45% (P= 0.03) for noncharged catheters and 11.25% (P = 0.03) for negatively charged catheters, compared with noncharged catheters. We describe a novel method of placing negative charge on electrodes during ablation that reduced coagulum formation. This may decrease thromboembolism-related complications with radiofrequency ablation procedures.

Effect of electrical polarization of hydroxyapatite ceramics on new bone formation.

PubMed

Itoh, S; Nakamura, S; Kobayashi, T; Shinomiya, K; Yamashita, K; Itoh, S

2006-03-01

Large surface charges can be induced on hydroxyapatite (HAp) ceramics by proton transport polarization, but this does not affect beta-tricalcium phosphate (TCP) because of its low polarizability. We wished to examine differences in osteogenic cell activity and new bone growth between positively or negatively surface-charged HAp and HAp/TCP plates using a calvarial bone defect model. In the first group of rats, test pieces were placed with their positively charged surfaces face down on the dura mater. In the second group, test pieces were placed with their negatively charged surfaces face down on the dura mater. A third group received noncharged test pieces. Histological examination, including enzymatic staining for osteoblasts and osteoclasts, was carried out. While no bone formation was observed at the pericranium, direct bone formation on the cranial bone debris and new bone growth expanded from the margins of the sites of injury to bridge across both the positively and negatively charged surfaces of HAp and HAp/TCP plates occurred. Electrical polarization of implanted plates, including positive charge, led to enhanced osteoblast activity, though decreased osteoclast activity was seen on the positively charged plate surface. Thus, polarization of HAp ceramics may modulate new bone formation and resorption.

Rational Design of Multilayer Collagen Nanosheets with Compositional and Structural Control.

PubMed

Jiang, Tao; Vail, Owen A; Jiang, Zhigang; Zuo, Xiaobing; Conticello, Vincent P

2015-06-24

Two collagen-mimetic peptides, CP(+) and CP(-), are reported in which the sequences comprise a multiblock architecture having positively charged N-terminal (Pro-Arg-Gly)3 and negatively charged C-terminal (Glu-Hyp-Gly)3 triad extensions, respectively. CP(+) rapidly self-associates into positively charged nanosheets based on a monolayer structure. In contrast, CP(-) self-assembles to form negatively charged monolayer nanosheets at a much slower rate, which can be accelerated in the presence of calcium(II) ion. A 2:1 mixture of unassociated CP(-) peptide with preformed CP(+) nanosheets generates structurally defined triple-layer nanosheets in which two CP(-) monolayers have formed on the identical surfaces of the CP(+) nanosheet template. Experimental data from electrostatic force microscopy (EFM) image analysis, zeta potential measurements, and charged nanoparticle binding assays support a negative surface charge state for the triple-layer nanosheets, which is the reverse of the positive surface charge state observed for the CP(+) monolayer nanosheets. The electrostatic complementarity between the CP(+) and CP(-) triple helical cohesive ends at the layer interfaces promotes a (CP(-)/CP(+)/CP(-)) compositional gradient along the z-direction of the nanosheet. This structurally informed approach represents an attractive strategy for the fabrication of two-dimensional nanostructures with compositional control.

Electrical structure in two thunderstorm anvil clouds

NASA Technical Reports Server (NTRS)

Marshall, Thomas C.; Rust, W. David; Winn, William P.; Gilbert, Kenneth E.

1989-01-01

Electrical structures in two thunderstorm anvil clouds (or 'anvils'), one in New Mexico, the other in Oklahoma, were investigated, using measurements of electric field by balloon-carried instruments and a one-dimensional model to calculate the time and spatial variations of electrical parameters in the clear air below the anvil. The electric field soundings through the two thunderstorm anvils showed similar charge structures; namely, negatively charged screening layers on the top and the bottom surfaces, a layer of positive charge in the interior, and one or two layers of zero charge. It is suggested that the positive charge originated in the main positive charge region normally found at high altitudes in the core of thunderclouds, and the negatively charged layers probably formed as screening layers, resulting from the discontinuity in the electrical conductivity at the cloud boundaries.

The effect of surface charge, negative and bipolar ionization on the deposition of airborne bacteria.

PubMed

Meschke, S; Smith, B D; Yost, M; Miksch, R R; Gefter, P; Gehlke, S; Halpin, H A

2009-04-01

A series of experiments were conducted to evaluate the effect of surface charge and air ionization on the deposition of airborne bacteria. The interaction between surface electrostatic potential and the deposition of airborne bacteria in an indoor environment was investigated using settle plates charged with electric potentials of 0, +/-2.5kV and +/-5kV. Results showed that bacterial deposition on the plates increased proportionally with increased potential to over twice the gravitational sedimentation rate at +5kV. Experiments were repeated under similar conditions in the presence of either negative or bipolar air ionization. Bipolar air ionization resulted in reduction of bacterial deposition onto the charged surfaces to levels nearly equal to gravitational sedimentation. In contrast, diffusion charging appears to have occurred during negative air ionization, resulting in an even greater deposition onto the oppositely charged surface than observed without ionization. Static charges on fomitic surfaces may attract bacteria resulting in deposition in excess of that expected by gravitational sedimentation or simple diffusion. Implementation of bipolar ionization may result in reduction of bacterial deposition. Fomitic surfaces are important vehicles for the transmission of infectious organisms. This study has demonstrated a simple strategy for minimizing charge related deposition of bacteria on surfaces.

Influence of natural organic matter on equilibrium adsorption of neutral and charged pharmaceuticals onto activated carbon.

PubMed

de Ridder, D J; Verliefde, A R D; Heijman, S G J; Verberk, J Q J C; Rietveld, L C; van der Aa, L T J; Amy, G L; van Dijk, J C

2011-01-01

Natural organic matter (NOM) can influence pharmaceutical adsorption onto granular activated carbon (GAC) by direct adsorption competition and pore blocking. However, in the literature there is limited information on which of these mechanisms is more important and how this is related to NOM and pharmaceutical properties. Adsorption batch experiments were carried out in ultrapure, waste- and surface water and fresh and NOM preloaded GAC was used. Twenty-one pharmaceuticals were selected with varying hydrophobicity and with neutral, negative or positive charge. The influence of NOM competition and pore blocking could not be separated. However, while reduction in surface area was similar for both preloaded GACs, up to 50% lower pharmaceutical removal was observed on wastewater preloaded GAC. This was attributed to higher hydrophobicity of wastewater NOM, indicating that NOM competition may influence pharmaceutical removal more than pore blocking. Preloaded GAC was negatively charged, which influenced removal of charged pharmaceuticals significantly. At a GAC dose of 6.7 mg/L, negatively charged pharmaceuticals were removed for 0-58%, while removal of positively charged pharmaceuticals was between 32-98%. Charge effects were more pronounced in ultrapure water, as it contained no ions to shield the surface charge. Solutes with higher log D could compete better with NOM, resulting in higher removal.

MIS capacitor studies on silicon carbide single crystals

NASA Technical Reports Server (NTRS)

Kopanski, J. J.

1990-01-01

Cubic SIC metal-insulator-semiconductor (MIS) capacitors with thermally grown or chemical-vapor-deposited (CVD) insulators were characterized by capacitance-voltage (C-V), conductance-voltage (G-V), and current-voltage (I-V) measurements. The purpose of these measurements was to determine the four charge densities commonly present in an MIS capacitor (oxide fixed charge, N(f); interface trap level density, D(it); oxide trapped charge, N(ot); and mobile ionic charge, N(m)) and to determine the stability of the device properties with electric-field stress and temperature. The section headings in the report include the following: Capacitance-voltage and conductance-voltage measurements; Current-voltage measurements; Deep-level transient spectroscopy; and Conclusions (Electrical characteristics of SiC MIS capacitors).

Presence of negative charge on the basal planes of New York talc.

PubMed

Burdukova, E; Becker, M; Bradshaw, D J; Laskowski, J S

2007-11-01

Potentiometric titration measurements as well as rheological measurements of talc aqueous suspensions indicate that the behavior of the New York talc particles is consistent with the presence of a negative charge on their basal planes. The possibility of the presence of a negative electrical charge on the basal planes of talc particles is analyzed in this paper. Samples of New York talc were studied using electron microprobe analysis and dehydration techniques and the exact chemical formula of New York talc was determined. It was found that there exists a deficiency of protons in the tetrahedral layers of talc, resulting from substitution of Si(4+) ions with Al(3+) and Ti(3+) ions. The comparison of the level of substitution of Si(4+) ions with ions of a lower valency was found to be of a similar order of magnitude as that found in other talc deposits. This strongly points to the presence of a negative charge on the talc basal planes.

Electrochemical energy storage devices comprising self-compensating polymers

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

Johnson, Paul; Bautista-Martinez, Jose Antonio; Friesen, Cody

The disclosed technology relates generally to devices comprising conductive polymers and more particularly to electrochemical devices comprising self-compensating conductive polymers. In one aspect, electrochemical energy storage device comprises a negative electrode comprising an active material including a redox-active polymer. The device additionally comprises a positive electrode comprising an active material including a redox-active polymer. The device further comprises an electrolyte material interposed between the negative electrode and positive electrode and configured to conduct mobile counterions therethrough between the negative electrode and positive electrode. At least one of the negative electrode redox-active polymer and the positive electrode redox-active polymer comprises amore » zwitterionic polymer unit configured to reversibly switch between a zwitterionic state in which the zwitterionic polymer unit has first and second charge centers having opposite charge states that compensate each other, and a non-zwitterionic state in which the zwitterionic polymer unit has one of the first and second charge centers whose charge state is compensated by mobile counterions.« less

Effects of O 2 and N 2/H 2 plasma treatments on the neuronal cell growth on single-walled carbon nanotube paper scaffolds

NASA Astrophysics Data System (ADS)

Yoon, Ok Ja; Lee, Hyun Jung; Jang, Yeong Mi; Kim, Hyun Woo; Lee, Won Bok; Kim, Sung Su; Lee, Nae-Eung

2011-08-01

The O 2 and N 2/H 2 plasma treatments of single-walled carbon nanotube (SWCNT) papers as scaffolds for enhanced neuronal cell growth were conducted to functionalize their surfaces with different functional groups and to roughen their surfaces. To evaluate the effects of the surface roughness and functionalization modifications of the SWCNT papers, we investigated the neuronal morphology, mitochondrial membrane potential, and acetylcholine/acetylcholinesterase levels of human neuroblastoma during SH-SY5Y cell growth on the treated SWCNT papers. Our results demonstrated that the plasma-chemical functionalization caused changes in the surface charge states with functional groups with negative and positive charges and then the increased surface roughness enhanced neuronal cell adhesion, mitochondrial membrane potential, and the level of neurotransmitter in vitro. The cell adhesion and mitochondrial membrane potential on the negatively charged SWCNT papers were improved more than on the positively charged SWCNT papers. Also, measurements of the neurotransmitter level showed an enhanced acetylcholine level on the negatively charged SWCNT papers compared to the positively charged SWCNT papers.

Important parameters affecting the cell voltage of aqueous electrical double-layer capacitors

NASA Astrophysics Data System (ADS)

Wu, Tzu-Ho; Hsu, Chun-Tsung; Hu, Chi-Chang; Hardwick, Laurence J.

2013-11-01

This study discusses and demonstrates how the open-circuit potential and charges stored in the working potential window on positive and negative electrodes affect the cell voltage of carbon-based electrical double-layer capacitors (EDLCs) in aqueous electrolytes. An EDLC consisting of two activated carbon electrodes is employed as the model system for identifying these key parameters although the potential window of water decomposition can be simply determined by voltammetric methods. First, the capacitive performances of an EDLC with the same charge on positive and negative electrodes are evaluated by cyclic voltammetric, charge-discharge, electrochemical impedance spectroscopic (EIS) analyses, and inductance-capacitance-resistance meter (LCR meter). The principles for obtaining the highest acceptable cell voltage of such symmetric ECs with excellent reversibility and capacitor-like behaviour are proposed. Aqueous charge-balanced EDLCs can be operated as high as 2.0 V with high energy efficiency (about 90%) and only 4% capacitance loss after the 600-cycle stability checking. The necessity of charge balance (but not capacitance balance) for positive and negative electrodes is substantiated from the lower acceptable cell voltage of charge-unbalanced EDLCs.

Hindered Diffusion in Polymeric Solutions Studied by Fluorescence Correlation Spectroscopy

PubMed Central

Zustiak, Silviya P.; Nossal, Ralph; Sackett, Dan L.

2011-01-01

Diffusion of molecules in the crowded and charged interior of the cell has long been of interest for understanding cellular processes. Here, we introduce a model system of hindered diffusion that includes both crowding and binding. In particular, we obtained the diffusivity of the positively charged protein, ribonuclease A (RNase), in solutions of dextrans of various charges (binding) and concentrations (crowding), as well as combinations of both, in a buffer of physiological ionic strength. Using fluorescence correlation spectroscopy, we observed that the diffusivity of RNase was unaffected by the presence of positively charged or neutral dextrans in the dilute regime but was affected by crowding at higher polymer concentrations. Conversely, protein diffusivity was significantly reduced by negatively charged dextrans, even at 0.4 μM (0.02% w/v) dextran. The diffusivity of RNase decreased with increasing concentrations of negative dextran, and the amount of bound RNase increased until it reached a plateau of ∼80% bound RNase. High salt concentrations were used to establish the electrostatic nature of the binding. Binding of RNase to the negatively charged dextrans was further confirmed by ultrafiltration. PMID:21723836

POx/Al2O3 stacks: Highly effective surface passivation of crystalline silicon with a large positive fixed charge

NASA Astrophysics Data System (ADS)

Black, Lachlan E.; Kessels, W. M. M. Erwin

2018-05-01

Thin-film stacks of phosphorus oxide (POx) and aluminium oxide (Al2O3) are shown to provide highly effective passivation of crystalline silicon (c-Si) surfaces. Surface recombination velocities as low as 1.7 cm s-1 and saturation current densities J0s as low as 3.3 fA cm-2 are obtained on n-type (100) c-Si surfaces passivated by 6 nm/14 nm thick POx/Al2O3 stacks deposited in an atomic layer deposition system and annealed at 450 °C. This excellent passivation can be attributed in part to an unusually large positive fixed charge density of up to 4.7 × 1012 cm-2, which makes such stacks especially suitable for passivation of n-type Si surfaces.

Proton transfer to charged platinum electrodes. A molecular dynamics trajectory study.

PubMed

Wilhelm, Florian; Schmickler, Wolfgang; Spohr, Eckhard

2010-05-05

A recently developed empirical valence bond (EVB) model for proton transfer on Pt(111) electrodes (Wilhelm et al 2008 J. Phys. Chem. C 112 10814) has been applied in molecular dynamics (MD) simulations of a water film in contact with a charged Pt surface. A total of seven negative surface charge densities σ between -7.5 and -18.9 µC cm(-2) were investigated. For each value of σ, between 30 and 84 initial conditions of a solvated proton within a water slab were sampled, and the trajectories were integrated until discharge of a proton occurred on the charged surfaces. We have calculated the mean rates for discharge and for adsorption of solvated protons within the adsorbed water layer in contact with the metal electrode as a function of surface charge density. For the less negative values of σ we observe a Tafel-like exponential increase of discharge rate with decreasing σ. At the more negative values this exponential increase levels off and the discharge process is apparently transport limited. Mechanistically, the Tafel regime corresponds to a stepwise proton transfer: first, a proton is transferred from the bulk into the contact water layer, which is followed by transfer of a proton to the charged surface and concomitant discharge. At the more negative surface charge densities the proton transfer into the contact water layer and the transfer of another proton to the surface and its discharge occur almost simultaneously.

Differential effects of DEAE negative mode chromatography and gel-filtration chromatography on the charge status of Helicobacter pylori neutrophil-activating protein

PubMed Central

Pan, Timothy; Tzeng, Huey-Fen

2017-01-01

Helicobacter pylori neutrophil-activating protein (HP-NAP) is involved in H. pylori-associated gastric inflammation. HP-NAP is also a vaccine candidate, a possible drug target, and a potential diagnostic marker for H. pylori-associated diseases. Previously, we purified recombinant HP-NAP by one-step diethylaminoethyl (DEAE) negative mode chromatography by collecting the unbound fraction at pH 8.0 at 4°C. It remains unclear why HP-NAP does not bind to DEAE resins at the pH above its isoelectric point during the purification. To investigate how pH affects the surface net charge of HP-NAP and its binding to DEAE resins during the purification, recombinant HP-NAP expressed in Escherichia coli was subjected to DEAE negative mode chromatography at pH ranging from 7.0 to 9.0 at 25°C and the surface charge of purified HP-NAP was determined by capillary electrophoresis. A minimal amount of HP-NAP was detected in the elution fraction of DEAE Sepharose resin at pH 8.5, whereas recombinant HP-NAP was detected in the elution fraction of DEAE Sephadex resin only at pH 7.0 and 8.0. The purified recombinant HP-NAP obtained from the unbound fractions was not able to bind to DEAE resins at pH 7.0 to 9.0. In addition, the surface charge of the purified HP-NAP was neutral at pH 7.0 to 8.0 and was either neutral or slightly negative at pH 8.5 and 9.0. However, recombinant HP-NAP purified from gel-filtration chromatography was able to bind to DEAE Sepharose resin at pH 7.0 to 9.0 and DEAE Sephadex resin at pH 7.0. At pH 8.5 and 9.0, only the negatively charged species of HP-NAP were found. Thus, recombinant HP-NAP with different charge status can be differentially purified by DEAE negative mode chromatography and gel-filtration chromatography. Furthermore, the charge distribution on the surface of HP-NAP, the presence of impure proteins, and the overall net charge of the resins all affect the binding of HP-NAP to DEAE resins during the negative purification. PMID:28328957

Differential effects of DEAE negative mode chromatography and gel-filtration chromatography on the charge status of Helicobacter pylori neutrophil-activating protein.

PubMed

Hong, Zhi-Wei; Yang, Yu-Chi; Pan, Timothy; Tzeng, Huey-Fen; Fu, Hua-Wen

2017-01-01

Helicobacter pylori neutrophil-activating protein (HP-NAP) is involved in H. pylori-associated gastric inflammation. HP-NAP is also a vaccine candidate, a possible drug target, and a potential diagnostic marker for H. pylori-associated diseases. Previously, we purified recombinant HP-NAP by one-step diethylaminoethyl (DEAE) negative mode chromatography by collecting the unbound fraction at pH 8.0 at 4°C. It remains unclear why HP-NAP does not bind to DEAE resins at the pH above its isoelectric point during the purification. To investigate how pH affects the surface net charge of HP-NAP and its binding to DEAE resins during the purification, recombinant HP-NAP expressed in Escherichia coli was subjected to DEAE negative mode chromatography at pH ranging from 7.0 to 9.0 at 25°C and the surface charge of purified HP-NAP was determined by capillary electrophoresis. A minimal amount of HP-NAP was detected in the elution fraction of DEAE Sepharose resin at pH 8.5, whereas recombinant HP-NAP was detected in the elution fraction of DEAE Sephadex resin only at pH 7.0 and 8.0. The purified recombinant HP-NAP obtained from the unbound fractions was not able to bind to DEAE resins at pH 7.0 to 9.0. In addition, the surface charge of the purified HP-NAP was neutral at pH 7.0 to 8.0 and was either neutral or slightly negative at pH 8.5 and 9.0. However, recombinant HP-NAP purified from gel-filtration chromatography was able to bind to DEAE Sepharose resin at pH 7.0 to 9.0 and DEAE Sephadex resin at pH 7.0. At pH 8.5 and 9.0, only the negatively charged species of HP-NAP were found. Thus, recombinant HP-NAP with different charge status can be differentially purified by DEAE negative mode chromatography and gel-filtration chromatography. Furthermore, the charge distribution on the surface of HP-NAP, the presence of impure proteins, and the overall net charge of the resins all affect the binding of HP-NAP to DEAE resins during the negative purification.

Polyelectrolyte-assisted preparation of gold nanocluster-doped silica particles with high incorporation efficiency and improved stability

NASA Astrophysics Data System (ADS)

Wang, Haonan; Huang, Zhenzhen; Guo, Zilong; Yang, Wensheng

2017-07-01

In this paper, we reported an approach for efficient incorporation of glutathione-capped gold nanoclusters (GSH-Au NCs) into silica particles with the assistance of a polyelectrolyte, poly-diallyldimethyl-ammoniumchloride (PDDA). In this approach, the negatively charged GSH-Au NCs were firstly mixed with the positively charged PDDA to form PDDA-Au NC complexes. Then, the complexes were added into a pre-hydrolyzed Stöber system to get the Au NCs-doped silica particles. With increased ratio of PDDA in the complexes, the negative charges on surface of the Au NCs were neutralized gradually and finally reversed to positive in presence of excess PDDA, which facilitated the incorporation of the Au NCs into the negatively charged silica matrix. Under the optimal amount of PDDA in the complexes, the incorporation efficiency of Au NCs could be as high as 88%. After being incorporated into the silica matrix, the Au NCs become much robust against pH and heavy metal ions attributed to the protection effect of silica and PDDA. This approach was also extendable to highly efficient incorporation of other negatively charged metal nanoclusters, such as bovine serum albumin-capped Cu nanoclusters, into silica matrix.

Functionalized nanoparticle interactions with polymeric membranes

PubMed Central

Ladner, D.A.; Steele, M.; Weir, A.; Hristovski, K.; Westerhoff, P.

2011-01-01

A series of experiments was performed to measure the retention of a class of functionalized nanoparticles (NPs) onporous (microfiltration and ultrafiltration) membranes. The findings impact engineered water and wastewater treatment using membrane technology, characterization and analytical schemes for NP detection, and the use of NPs in waste treatment scenarios. The NPs studied were composed of silver, titanium dioxide, and gold; had organic coatings to yield either positive or negative surface charge; and were between 2 and 10 nm in diameter. NP solutions were applied to polymeric membranes composed of different materials and pore sizes (ranging from ~2 nm [3 kDa molecular weight cutoff] to 0.2 μm). Greater than 99% rejection was observed of positively charged NPs by negatively charged membranes even though pore diameters were up to 20 times the NP diameter; thus, sorption caused rejection. Negatively charged NPs were less well rejected, but behavior was dependant not only on surface functionality but on NP core material (Ag, TiO2, or Au). NP rejection depended more upon NP properties than membrane properties; all of the negatively charged polymeric membranes behaved similarly. The NP-membrane interaction behavior fell into four categories, which are defined and described here. PMID:22177020

Increasing binding density of yeast cells by control of surface charge with allylamine grafting to ion modified polymer surfaces.

PubMed

Tran, Clara T H; Kondyurin, Alexey; Chrzanowski, Wojciech; Bilek, Marcela M M; McKenzie, David R

2014-10-01

Plasma immersion ion implantation (PIII) treatment of polymers creates a biointerface capable of direct covalent immobilization of biomolecules. The immobilization of protein molecules is achieved by covalent bonds formed between embedded radicals on the treated surface and amino acid side chains and cells can be immobilized through cell-wall proteins. The attachment density of negatively charged entities on a PIII treated surface is inhibited by its negative surface charge at neutral pH. To reduce the negative charge of PIII treated surfaces in phosphate buffer (pH 7.4, 11mM), we develop an effective approach of grafting allylamine monomers onto the treated surface. The results reveal reactions between allylamine and radicals on the PIII treated surface. One of these triggers polymerization, increasing the number of amine groups grafted. As a consequence, the PIII treated polystyrene surface after allylamine exposure becomes more hydrophobic and less negatively charged in phosphate buffer. Using yeast cells as an example, we have shown a significant improvement (6-15 times) of cell density immobilized on the PIII treated surface after exposure to allylamine. Copyright © 2014 Elsevier B.V. All rights reserved.

High-energy e- /e+ spectrometer via coherent interaction in a bent crystal

NASA Astrophysics Data System (ADS)

Bagli, Enrico; Guidi, Vincenzo; Howard, Alexander

2018-01-01

We propose a novel spectrometer based on the crystal channeling effect capable of discriminating between positive and negative particles well beyond the TeV energy scale. The atomic order of a crystalline structure generates an electrostatic field built up by all the atoms in the crystals, which confines charged particle trajectories between neighbouring atomic planes. Through such an interaction in a tiny curved crystal, the same dynamical action on the highest energy particles as that of a huge superconducting magnet is achieved. Depending on the charge sign, points of equilibrium of the oscillatory motion under channeling lie between or on atomic planes for positive and negative particles, respectively, forcing positive particles to stably oscillate far from the planes, while negative ones repeatedly cross them. The different interaction rate with atomic planes causes a tremendous discrepancy between the deflection efficiency of positive and negative particles under channeling. We suggest the use of interactions between charged particles and oriented bent crystals as a novel non-cryogenic passive charge spectrometer to aid the search for dark matter in the Universe in satellite-borne experiment. The limited angular acceptance makes this technique particularly suited for directional local sources of energetic charged particles.

Microelectrophoretic study of calcium oxalate monohydrate in macromolecular solutions

NASA Technical Reports Server (NTRS)

Curreri, P. A.; Onoda, G. Y., Jr.; Finlayson, B.

1987-01-01

Electrophoretic mobilities were measured for calcium oxalate monohydrate (COM) in solutions containing macromolecules. Two mucopolysaccharides (sodium heparin and chondroitin sulfate) and two proteins (positively charged lysozyme and negatively charged bovine serum albumin) were studied as adsorbates. The effects of pH, calcium oxalate surface charge (varied by calcium or oxalate ion activity), and citrate concentration were investigated. All four macromolecules showed evidence for adsorption. The macromolecule concentrations needed for reversing the surface charge indicated that the mucopolysaccharides have greater affinity for the COM surface than the proteins. Citrate ions at high concentrations appear to compete effectively with the negative protein for surface sites but show no evidence for competing with the positively charged protein.

Stepped electrophoresis for movement and concentration of DNA

DOEpatents

Miles, Robin R.; Wang, Amy Wei-Yun; Mariella, Jr., Raymond P.

2005-03-15

A fluidic channel patterned with a series of thin-film electrodes makes it possible to move and concentrate DNA in a fluid passing through the fluidic channel. The DNA has an inherent negative charge and by applying a voltage between adjacent electrodes the DNA is caused to move. By using a series of electrodes, when one electrode voltage or charge is made negative with respect to adjacent electrodes, the DNA is repelled away from this electrode and attached to a positive charged electrode of the series. By sequentially making the next electrode of the series negative, the DNA can be moved to and concentrated over the remaining positive electrodes.

Neutralization by a Corona Discharge Ionizer in Nitrogen Atmosphere

NASA Astrophysics Data System (ADS)

Ikeuchi, Toru; Takahashi, Kazunori; Ohkubo, Takahiro; Fujiwara, Tamiya

An electrostatic neutralization of multilayer-loading silicon wafers is demonstrated using a corona discharge ionizer in nitrogen atmosphere, where ac and dc voltages are applied to two needle electrodes for generation of the negative- and positive-charged particles, respectively. We observe a surface potential of the silicon wafer decreases from ±1kV to ±20V within three seconds. Moreover, the density profiles of the charged particles generated by the electrodes are experimentally and theoretically investigated in nitrogen and air atmospheres. Our results show the possibility that the negative-charged particles contributing to the electrostatic neutralization are electrons and negative ions in nitrogen and air atmospheres, respectively.

Adhesion signals of phospholipid vesicles at an electrified interface.

PubMed

DeNardis, Nadica Ivošević; Žutić, Vera; Svetličić, Vesna; Frkanec, Ruža

2012-09-01

General adhesion behavior of phospholipid vesicles was examined in a wide range of potentials at the mercury electrode by recording time-resolved adhesion signals. It was demonstrated that adhesion-based detection is sensitive to polar headgroups in phospholipid vesicles. We identified a narrow potential window around the point of zero charge of the electrode where the interaction of polar headgroups of phosphatidylcholine vesicles with the substrate is manifested in the form of bidirectional signals. The bidirectional signal is composed of the charge flow due to the nonspecific interaction of vesicle adhesion and spreading and of the charge flow due to a specific interaction of the negatively charged electrode and the most exposed positively charged choline headgroups. These signals are expected to appear only when the electrode surface charge density is less than the surface charge density of the choline groups at the contact interface. In comparison, for the negatively charged phosphatidylserine vesicles, we identified the potential window at the mercury electrode where charge compensation takes place, and bidirectional signals were not detected.

Maintenance of coat protein N-terminal net charge and not primary sequence is essential for zucchini yellow mosaic virus systemic infectivity.

PubMed

Kimalov, Boaz; Gal-On, Amit; Stav, Ran; Belausov, Eduard; Arazi, Tzahi

2004-11-01

Zucchini yellow mosaic virus (ZYMV) surface exposed coat protein (CP) N-terminal domain (Nt) is 43 aa long and contains an equal number of positively and negatively charged amino acid residues (CP-Nt net charge = 0). A ZYMV-AGII truncation mutant lacking the first 20 aa of its CP-Nt (AGII-CP Delta 20; CP-Nt net charge = +2) was found to be systemically non-infectious even though AGII mutants harbouring larger CP-Nt deletions were previously demonstrated to be fully infectious. Nevertheless, AGII-CP Delta 20 infectivity was restored by fusion to its CP-Nt two Asp residues or a negatively charged Myc peptide, both predicted to neutralize CP-Nt net positive charge. To evaluate further the significance of CP-Nt net charge for AGII infectivity, a series of CP-Nt net charge mutants was generated and analysed for systemic infectivity of squash plants. AGII-CP(KKK) harbouring a CP-Nt amino fusion of three Lys residues (CP-Nt net charge = +3) was not systemically infectious. Addition of up to four Asp residues to CP-Nt did not abolish virus infectivity, although certain mutants were genetically unstable and had delayed infectivity. Addition of five negatively charged residues abolished infectivity (AGII-CP(DDDDD); CP-Nt net charge = -5) even though a recombinant CP(DDDDD) could assemble into potyviral-like particle in bacteria. Neutralization of CP-Nt net charge by fusing Asp or Lys residues recovered infectivity of AGII-CP(KKK) and AGII-CP(DDDDD). GFP-tagging of these mutants has demonstrated that both viruses have defective cell-to-cell movement. Together, these findings suggest that maintenance of CP-Nt net charge and not primary sequence is essential for ZYMV infectivity.

Negative charge emission due to excimer laser bombardment of sodium trisilicate glass

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

Langford, S.C.; Jensen, L.C.; Dickinson, J.T.

We describe measurements of negative charge emission accompanying irradiation of sodium trisilicate glass (Na{sub 2}O{center dot}3SiO{sub 2}) with 248-nm excimer laser light at fluences on the order of 2 J/cm{sup 2} per pulse, i.e., at the threshold for ablative etching of the glass surface. The negative charge emission consists of a very prompt photoelectron burst coincident with the laser pulse, followed by a much slower plume of electrons and negative ions traveling with a high density cloud of positive ions, previously identified as primarily Na{sup +}. Using combinations of {bold E} and {bold B} fields in conjunction with time-of-flight methods,more » the negative ions were successfully separated from the plume and tentatively identified as O{sup {minus}}, Si{sup {minus}}, NaO{sup {minus}}, and perhaps NaSi{sup {minus}}. These negative species are probably formed by gas phase collisions in the near-surface region which result in electron attachment.« less

Enhanced electrohydrodynamic force generation in a two-stroke cycle dielectric-barrier-discharge plasma actuator

NASA Astrophysics Data System (ADS)

Sato, Shintaro; Takahashi, Masayuki; Ohnishi, Naofumi

2017-05-01

An approach for electrohydrodynamic (EHD) force production is proposed with a focus on a charge cycle on a dielectric surface. The cycle, consisting of positive-charging and neutralizing strokes, is completely different from the conventional methodology, which involves a negative-charging stroke, in that the dielectric surface charge is constantly positive. The two-stroke charge cycle is realized by applying a DC voltage combined with repetitive pulses. Simulation results indicate that the negative pulse eliminates the surface charge accumulated during constant voltage phase, resulting in repetitive EHD force generation. The time-averaged EHD force increases almost linearly with increasing repetitive pulse frequency and becomes one order of magnitude larger than that driven by the sinusoidal voltage, which has the same peak-to-peak voltage.

Minimization of Impact from Electric Vehicle Supply Equipment to the Electric Grid Using a Dynamically Controlled Battery Bank for Peak Load Shaving

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

Castello, Charles C

This research presents a comparison of two control systems for peak load shaving using local solar power generation (i.e., photovoltaic array) and local energy storage (i.e., battery bank). The purpose is to minimize load demand of electric vehicle supply equipment (EVSE) on the electric grid. A static and dynamic control system is compared to decrease demand from EVSE. Static control of the battery bank is based on charging and discharging to the electric grid at fixed times. Dynamic control, with 15-minute resolution, forecasts EVSE load based on data analysis of collected data. In the proposed dynamic control system, the sigmoidmore » function is used to shave peak loads while limiting scenarios that can quickly drain the battery bank. These control systems are applied to Oak Ridge National Laboratory s (ORNL) solar-assisted electric vehicle (EV) charging stations. This installation is composed of three independently grid-tied sub-systems: (1) 25 EVSE; (2) 47 kW photovoltaic (PV) array; and (3) 60 kWh battery bank. The dynamic control system achieved the greatest peak load shaving, up to 34% on a cloudy day and 38% on a sunny day. The static control system was not ideal; peak load shaving was 14.6% on a cloudy day and 12.7% on a sunny day. Simulations based on ORNL data shows solar-assisted EV charging stations combined with the proposed dynamic battery control system can negate up to 89% of EVSE load demand on sunny days.« less

Optical pumping of the electronic and nuclear spin of single charge-tunable quantum dots.

PubMed

Bracker, A S; Stinaff, E A; Gammon, D; Ware, M E; Tischler, J G; Shabaev, A; Efros, Al L; Park, D; Gershoni, D; Korenev, V L; Merkulov, I A

2005-02-04

We present a comprehensive examination of optical pumping of spins in individual GaAs quantum dots as we change the net charge from positive to neutral to negative with a charge-tunable heterostructure. Negative photoluminescence polarization memory is enhanced by optical pumping of ground state electron spins, which we prove with the first measurements of the Hanle effect on an individual quantum dot. We use the Overhauser effect in a high longitudinal magnetic field to demonstrate efficient optical pumping of nuclear spins for all three charge states of the quantum dot.

Optical Pumping of the Electronic and Nuclear Spin of Single Charge-Tunable Quantum Dots

NASA Astrophysics Data System (ADS)

Bracker, A. S.; Stinaff, E. A.; Gammon, D.; Ware, M. E.; Tischler, J. G.; Shabaev, A.; Efros, Al. L.; Park, D.; Gershoni, D.; Korenev, V. L.; Merkulov, I. A.

2005-02-01

We present a comprehensive examination of optical pumping of spins in individual GaAs quantum dots as we change the net charge from positive to neutral to negative with a charge-tunable heterostructure. Negative photoluminescence polarization memory is enhanced by optical pumping of ground state electron spins, which we prove with the first measurements of the Hanle effect on an individual quantum dot. We use the Overhauser effect in a high longitudinal magnetic field to demonstrate efficient optical pumping of nuclear spins for all three charge states of the quantum dot.

Recovery of Utility Fixed Costs: Utility, Consumer, Environmental and Economist Perspectives

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

Wood, Lisa; Hemphill, Ross; Howat, John

Utilities recover costs for providing electric service to retail customers through a combination of rate components that together comprise customers’ monthly electric bills. Rates and rate designs are set by state regulators and vary by jurisdiction, utility and customer class. In addition to the fundamental tenet of setting fair and reasonable rates, rate design balances economic efficiency, equity and fairness, customer satisfaction, utility revenue stability, and customer price and bill stability.1 At the most basic level, retail electricity bills in the United States typically include a fixed monthly customer charge — a set dollar amount regardless of energy usage —more » and a volumetric energy charge for each kilowatt-hour consumed.2 The energy charge may be flat across all hours, vary by usage level (for example, higher rates at higher levels of usage), or vary based on time of consumption.3 While some utility costs, such as fuel costs, clearly vary according to electricity usage, other costs are “fixed” over the short run — generally, those that do not vary over the course of a year. Depending on your point of view, and whether the state’s electricity industry has been restructured or remains vertically integrated, the set of costs that are “fixed” may be quite limited. Or the set may extend to all capacity costs for generation, transmission and distribution. In the long run, all costs are variable. In the context of flat or declining loads in some regions, utilities are proposing a variety of changes to retail rate designs, particularly for residential customers, to recover fixed costs. In this report, authors representing utility (Chapter 1), consumer (Chapter 2), environmentalist (Chapter 3) and economist (Chapter 4) perspectives discuss fixed costs for electric utilities and set out their principles for recovering those costs. The table on the next page summarizes each author’s relative preferences for various options for fixed cost recovery, some of which may be used in combination.4 The specific design of any ratemaking option matters crucially, so a general preference for a given option does not indicate support for any particular application.« less

SH3-like motif-containing C-terminal domain of staphylococcal teichoic acid transporter suggests possible function.

PubMed

Ko, Tzu-Ping; Tseng, Shih-Ting; Lai, Shu-Jung; Chen, Sheng-Chia; Guan, Hong-Hsiang; Shin Yang, Chia; Jung Chen, Chun; Chen, Yeh

2016-09-01

The negatively charged bacterial polysaccharides-wall teichoic acids (WTAs) are synthesized intracellularly and exported by a two-component transporter, TagGH, comprising a transmembrane subunit TagG and an ATPase subunit TagH. We determined the crystal structure of the C-terminal domain of TagH (TagH-C) to investigate its function. The structure shows an N-terminal SH3-like subdomain wrapped by a C-terminal subdomain with an anti-parallel β-sheet and an outer shell of α-helices. A stretch of positively charged surface across the subdomain interface is flanked by two negatively charged regions, suggesting a potential binding site for negatively charged polymers, such as WTAs or acidic peptide chains. Proteins 2016; 84:1328-1332. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Negative space charge effects in photon-enhanced thermionic emission solar converters

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

Segev, G.; Weisman, D.; Rosenwaks, Y.

2015-07-06

In thermionic energy converters, electrons in the gap between electrodes form a negative space charge and inhibit the emission of additional electrons, causing a significant reduction in conversion efficiency. However, in Photon Enhanced Thermionic Emission (PETE) solar energy converters, electrons that are reflected by the electric field in the gap return to the cathode with energy above the conduction band minimum. These electrons first occupy the conduction band from which they can be reemitted. This form of electron recycling makes PETE converters less susceptible to negative space charge loss. While the negative space charge effect was studied extensively in thermionicmore » converters, modeling its effect in PETE converters does not account for important issues such as this form of electron recycling, nor the cathode thermal energy balance. Here, we investigate the space charge effect in PETE solar converters accounting for electron recycling, with full coupling of the cathode and gap models, and addressing conservation of both electric and thermal energy. The analysis shows that the negative space charge loss is lower than previously reported, allowing somewhat larger gaps compared to previous predictions. For a converter with a specific gap, there is an optimal solar flux concentration. The optimal solar flux concentration, the cathode temperature, and the efficiency all increase with smaller gaps. For example, for a gap of 3 μm the maximum efficiency is 38% and the optimal flux concentration is 628, while for a gap of 5 μm the maximum efficiency is 31% and optimal flux concentration is 163.« less

Enhancing biocompatibility of D-oligopeptide hydrogels by negative charges.

PubMed

Hyland, Laura L; Twomey, Julianne D; Vogel, Savannah; Hsieh, Adam H; Yu, Y Bruce

2013-02-11

Oligopeptide hydrogels are emerging as useful matrices for cell culture with commercial products on the market, but L-oligopeptides are labile to proteases. An obvious solution is to create D-oligopeptide hydrogels, which lack enzymatic recognition. However, D-oligopeptide matrices do not support cell growth as well as L-oligopeptide matrices. In addition to chiral interactions, many cellular activities are strongly governed by charge-charge interactions. In this work, the effects of chirality and charge on human mesenchymal stem cell (hMSC) behavior were studied using hydrogels assembled from oppositely charged oligopeptides. It was found that negative charges significantly improved hMSC viability and proliferation in D-oligopeptide gels but had little effect on their interactions with L-oligopeptide gels. This result points to the possibility of using charge and other factors to engineer biomaterials whose chirality is distinct from that of natural biomaterials, but whose performance is close to that of natural biomaterials.

33 CFR 140.103 - Annual inspection of fixed OCS facilities.

Code of Federal Regulations, 2011 CFR

2011-07-01

...), inspections by Coast Guard marine inspectors and Bureau of Ocean Energy Management, Regulation, and... Officer in Charge, Marine Inspection. A copy of the completed form must be kept for 2 years after the...

Effects of different blasting materials on charge generation and decay on titanium surface after sandblasting.

PubMed

Guo, Cecilia Yan; Hong Tang, Alexander Tin; Hon Tsoi, James Kit; Matinlinna, Jukka Pekka

2014-04-01

It has been reported that sandblasting titanium with alumina (Al2O3) powder could generate a negative electric charge on titanium surface. This has been proven to promote osteoblast activities and possibly osseointegration. The purpose of this pilot study was to investigate the effects of different blasting materials, in terms of the grit sizes and electro-negativity, on the generation of a negative charge on the titanium surface. The aim was also to make use of these results to deduct the underlying mechanism of charge generation by sandblasting. Together 60 c.p. 2 titanium plates were machine-cut and polished for sandblasting, and divided into 6 groups with 10 plates in each. Every plate in the study groups was sandblasted with one of the following 6 powder materials: 110µm Al2O3 grits, 50µm Al2O3 grits, 150-300µm glass beads, 45-75µm glass beads, 250µm Al powder and 44µm Al powder. The static voltage on the surface of every titanium plate was measured immediately after sandblasting. The static voltages of the titanium plates were recorded and processed using statistical analysis. The results suggested that only sandblasting with 45-75µm glass beads generated a positive charge on titanium, while using all other blasting materials lead to a negative charge. Furthermore, blasting grits of the same powder material but of different sizes might lead to different amount and polarity of the charges. This triboelectric effect is likely to be the main mechanism for charge generation through sandblasting. Copyright © 2014 Elsevier Ltd. All rights reserved.

Lipids and topological rules of membrane protein assembly: balance between long and short range lipid-protein interactions.

PubMed

Vitrac, Heidi; Bogdanov, Mikhail; Heacock, Phil; Dowhan, William

2011-04-29

The N-terminal six-transmembrane domain (TM) bundle of lactose permease of Escherichia coli is uniformly inverted when assembled in membranes lacking phosphatidylethanolamine (PE). Inversion is dependent on the net charge of cytoplasmically exposed protein domains containing positive and negative residues, net charge of the membrane surface, and low hydrophobicity of TM VII acting as a molecular hinge between the two halves of lactose permease (Bogdanov, M., Xie, J., Heacock, P., and Dowhan, W. (2008) J. Cell Biol. 182, 925-935). Net neutral lipids suppress the membrane translocation potential of negatively charged amino acids, thus increasing the cytoplasmic retention potential of positively charged amino acids. Herein, TM organization of sucrose permease (CscB) and phenylalanine permease (PheP) as a function of membrane lipid composition was investigated to extend these principles to other proteins. For CscB, topological dependence on PE only becomes evident after a significant increase in the net negative charge of the cytoplasmic surface of the N-terminal TM bundle. High negative charge is required to overcome the thermodynamic block to inversion due to the high hydrophobicity of TM VII. Increasing the positive charge of the cytoplasmic surface of the N-terminal TM hairpin of PheP, which is misoriented in PE-lacking cells, favors native orientation in the absence of PE. PheP and CscB also display co-existing dual topologies dependent on changes in the charge balance between protein domains and the membrane lipids. Therefore, the topology of both permeases is dependent on PE. However, CscB topology is governed by thermodynamic balance between opposing lipid-dependent electrostatic and hydrophobic interactions.

A quantitative analysis of municipal solid waste disposal charges in China.

PubMed

Wu, Jian; Zhang, Weiqian; Xu, Jiaxuan; Che, Yue

2015-03-01

Rapid industrialization and economic development have caused a tremendous increase in municipal solid waste (MSW) generation in China. China began implementing a policy of MSW disposal fees for household waste management at the end of last century. Three charging methods were implemented throughout the country: a fixed disposal fee, a potable water-based disposal fee, and a plastic bag-based disposal fee. To date, there has been little qualitative or quantitative analysis on the effectiveness of this relatively new policy. This paper provides a general overview of MSW fee policy in China, attempts to verify whether the policy is successful in reducing general waste collected, and proposes an improved charging system to address current problems. The paper presents an empirical statistical analysis of policy effectiveness derived from an environmental Kuznets curve (EKC) test on panel data of China. EKC tests on different kinds of MSW charge systems were then examined for individual provinces or cities. A comparison of existing charging systems was conducted using environmental and economic criteria. The results indicate the following: (1) the MSW policies implemented over the study period were effective in the reduction of waste generation, (2) the household waste discharge fee policy did not act as a strong driver in terms of waste prevention and reduction, and (3) the plastic bag-based disposal fee appeared to be performing well according to qualitative and quantitative analysis. Based on current situation of waste discharging management in China, a three-stage transitional charging scheme is proposed and both advantages and drawbacks discussed. Evidence suggests that a transition from a fixed disposal fee to a plastic bag-based disposal fee involving various stakeholders should be the next objective of waste reduction efforts.

The electrokinetic behavior of calcium oxalate monohydrate in macromolecular solutions

NASA Technical Reports Server (NTRS)

Curreri, P. A.; Onoda, G. Y., Jr.; Finlayson, B.

1988-01-01

Electrophoretic mobilities were measured for calcium oxalate monohydrate (COM) in solutions containing macromolecules. Two mucopolysaccharides (sodium heparin and chrondroitin sulfate) and two proteins (positively charged lysozyme and negatively charged bovine serum albumin) were studied as adsorbates. The effects of pH, calcium oxalate surface charge (varied by calcium or oxalate ion activity), and citrate concentration were investigated. All four macromolecules showed evidence for chemical adsorption. The macromolecule concentrations needed for reversing the surface charge indicated that the mucopopolysacchrides have greater affinity for the COM surface than the proteins. The amount of proteins that can chemically adsorb appears to be limited to approximately one monomolecular layer. When the surface charge is high, an insufficient number of proteins can chemically adsorb to neutralize or reverse the surface charge. The remaining surface charge is balanced by proteins held near the surface by longer range electrostatic forces only. Citrate ions at high concentrations appear to compete effectively with the negative protein for surface sites but show no evidence for competing with the positively charged protein.

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.

Charge Segregation and Low Hydrophobicity Are Key Features of Ribosomal Proteins from Different Organisms*

PubMed Central

Fedyukina, Daria V.; Jennaro, Theodore S.; Cavagnero, Silvia

2014-01-01

Ribosomes are large and highly charged macromolecular complexes consisting of RNA and proteins. Here, we address the electrostatic and nonpolar properties of ribosomal proteins that are important for ribosome assembly and interaction with other cellular components and may influence protein folding on the ribosome. We examined 50 S ribosomal subunits from 10 species and found a clear distinction between the net charge of ribosomal proteins from halophilic and non-halophilic organisms. We found that ∼67% ribosomal proteins from halophiles are negatively charged, whereas only up to ∼15% of ribosomal proteins from non-halophiles share this property. Conversely, hydrophobicity tends to be lower for ribosomal proteins from halophiles than for the corresponding proteins from non-halophiles. Importantly, the surface electrostatic potential of ribosomal proteins from all organisms, especially halophiles, has distinct positive and negative regions across all the examined species. Positively and negatively charged residues of ribosomal proteins tend to be clustered in buried and solvent-exposed regions, respectively. Hence, the majority of ribosomal proteins is characterized by a significant degree of intramolecular charge segregation, regardless of the organism of origin. This key property enables the ribosome to accommodate proteins within its complex scaffold regardless of their overall net charge. PMID:24398678

Molecular and phenotypic aspects of CHD7 mutation in CHARGE syndrome

PubMed Central

Zentner, Gabriel E.; Layman, Wanda S.; Martin, Donna M.; Scacheri, Peter C.

2010-01-01

CHARGE syndrome (Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities, and Ear abnormalities (including deafness) is a genetic disorder characterized by a specific and a recognizable pattern of anomalies. De novo mutations in the gene encoding chromodomain helicase DNA binding protein 7 (CHD7) are the major cause of CHARGE syndrome. Here, we review the clinical features of 379 CHARGE patients who tested positive or negative for mutations in CHD7. We found that CHARGE individuals with CHD7 mutations more commonly have ocular colobomas, temporal bone anomalies (semicircular canal hypoplasia/dysplasia), and facial nerve paralysis compared with mutation negative individuals. We also highlight recent genetic and genomic studies that have provided functional insights into CHD7 and the pathogenesis of CHARGE syndrome. PMID:20186815

Effect of Fe{sub 3}O{sub 4} nanoparticles on space charge distribution in propylene carbonate under impulse voltage

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

Sima, Wenxia, E-mail: cqsmwx@cqu.edu.cn; Song, He; Yang, Qing

2015-12-15

Addition of nanoparticles of the ferromagnetic material Fe{sub 3}O{sub 4} can increase the positive impulse breakdown voltage of propylene carbonate by 11.65%. To further investigate the effect of ferromagnetic nanoparticles on the space charge distribution in the discharge process, the present work set up a Kerr electro-optic field mapping measurement system using an array photodetector to carry out time-continuous measurement of the electric field and space charge distribution in propylene carbonate before and after modification. Test results show that fast electrons can be captured by Fe{sub 3}O{sub 4} nanoparticles and converted into relatively slow, negatively charged particles, inhibiting the generationmore » and transportation of the space charge, especially the negative space charge.« less

International Conference on Fixed Point Theory and Applications (Colloque International Theorie Du Point Fixe et Applications)

DTIC Science & Technology

1989-06-09

Theorem and the Perron - Frobenius Theorem in matrix theory. We use the Hahn-Banach theorem and do not use any fixed-point related concepts. 179 A...games defined b’, tions 87 Isac G. Fixed point theorems on convex cones , generalized pseudo-contractive mappings and the omplementarity problem 89...and (II), af(x) ° denotes the negative polar cone ot of(x). This condition are respectively called "inward" and "outward". Indeed, when X is convex

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

Torii, Hajime, E-mail: torii.hajime@shizuoka.ac.jp

The intensity of the band at ∼200 cm{sup −1} (∼6 THz) in the Terahertz spectrum of liquid water mainly arises from the modulations of the extent of intermolecular charge transfer through hydrogen bonds, called intermolecular charge fluxes, occurring upon molecular translations along the O…H hydrogen bonds. To obtain reasonable spectral profiles from simulations, it is necessary to effectively incorporate the effects of those intermolecular charge fluxes, but apparently it is not possible by simple classical molecular dynamics simulations with fixed atomic partial charges even if they are amended by molecular induced dipoles due to intermolecular electrostatic interactions. The present paper showsmore » how we can do reasonably correct spectral simulations, without resorting to fully ab initio molecular dynamics.« less

Charge-transfer modified embedded atom method dynamic charge potential for Li-Co-O system

NASA Astrophysics Data System (ADS)

Kong, Fantai; Longo, Roberto C.; Liang, Chaoping; Nie, Yifan; Zheng, Yongping; Zhang, Chenxi; Cho, Kyeongjae

2017-11-01

To overcome the limitation of conventional fixed charge potential methods for the study of Li-ion battery cathode materials, a dynamic charge potential method, charge-transfer modified embedded atom method (CT-MEAM), has been developed and applied to the Li-Co-O ternary system. The accuracy of the potential has been tested and validated by reproducing a variety of structural and electrochemical properties of LiCoO2. A detailed analysis on the local charge distribution confirmed the capability of this potential for dynamic charge modeling. The transferability of the potential is also demonstrated by its reliability in describing Li-rich Li2CoO2 and Li-deficient LiCo2O4 compounds, including their phase stability, equilibrium volume, charge states and cathode voltages. These results demonstrate that the CT-MEAM dynamic charge potential could help to overcome the challenge of modeling complex ternary transition metal oxides. This work can promote molecular dynamics studies of Li ion cathode materials and other important transition metal oxides systems that involve complex electrochemical and catalytic reactions.

Charge-transfer modified embedded atom method dynamic charge potential for Li-Co-O system.

PubMed

Kong, Fantai; Longo, Roberto C; Liang, Chaoping; Nie, Yifan; Zheng, Yongping; Zhang, Chenxi; Cho, Kyeongjae

2017-11-29

To overcome the limitation of conventional fixed charge potential methods for the study of Li-ion battery cathode materials, a dynamic charge potential method, charge-transfer modified embedded atom method (CT-MEAM), has been developed and applied to the Li-Co-O ternary system. The accuracy of the potential has been tested and validated by reproducing a variety of structural and electrochemical properties of LiCoO 2 . A detailed analysis on the local charge distribution confirmed the capability of this potential for dynamic charge modeling. The transferability of the potential is also demonstrated by its reliability in describing Li-rich Li 2 CoO 2 and Li-deficient LiCo 2 O 4 compounds, including their phase stability, equilibrium volume, charge states and cathode voltages. These results demonstrate that the CT-MEAM dynamic charge potential could help to overcome the challenge of modeling complex ternary transition metal oxides. This work can promote molecular dynamics studies of Li ion cathode materials and other important transition metal oxides systems that involve complex electrochemical and catalytic reactions.

Multiplicity distributions of charged hadrons in vp and charged current interactions

NASA Astrophysics Data System (ADS)

Jones, G. T.; Jones, R. W. L.; Kennedy, B. W.; Morrison, D. R. O.; Mobayyen, M. M.; Wainstein, S.; Aderholz, M.; Hantke, D.; Katz, U. F.; Kern, J.; Schmitz, N.; Wittek, W.; Borner, H. P.; Myatt, G.; Radojicic, D.; Burke, S.

1992-03-01

Using data on vp andbar vp charged current interactions from a bubble chamber experiment with BEBC at CERN, the multiplicity distributions of charged hadrons are investigated. The analysis is based on ˜20000 events with incident v and ˜10000 events with incidentbar v. The invariant mass W of the total hadronic system ranges from 3 GeV to ˜14 GeV. The experimental multiplicity distributions are fitted by the binomial function (for different intervals of W and in different intervals of the rapidity y), by the Levy function and the lognormal function. All three parametrizations give acceptable values for X 2. For fixed W, forward and backward multiplicities are found to be uncorrelated. The normalized moments of the charged multiplicity distributions are measured as a function of W. They show a violation of KNO scaling.

Like-charge attraction in a one-dimensional setting: the importance of being odd

NASA Astrophysics Data System (ADS)

Trizac, Emmanuel; Téllez, Gabriel

2018-03-01

From cement cohesion to DNA condensation, a proper statistical physics treatment of systems with long-range forces is important for a number of applications in physics, chemistry, and biology. We compute here the effective force between fixed charged macromolecules, screened by oppositely charged mobile ions (counterions). We treat the problem in a one-dimensional configuration that allows for interesting discussion and derivation of exact results, remaining at a level of mathematical difficulty compatible with an undergraduate course. Emphasis is put on the counterintuitive but fundamental phenomenon of like-charge attraction, which our treatment brings for the first time to the level of undergraduate teaching. The parity of the number of counterions is shown to play a prominent role, which sheds light on the binding mechanism at work when like-charge macromolecules do attract.

Improved understanding of the recombination rate at inverted p+ silicon surfaces

NASA Astrophysics Data System (ADS)

To, Alexander; Ma, Fajun; Hoex, Bram

2017-08-01

The effect of positive fixed charge on the recombination rate at SiN x -passivated p+ surfaces is studied in this work. It is shown that a high positive fixed charge on a low defect density, passivated doped surface can result in a near injection level independent lifetime in a certain injection level range. This behaviour is modelled with advanced computer simulations using Sentaurus TCAD, which replicates the measurements conditions during a photoconductance based effective minority carrier lifetime measurement. The resulting simulations show that the shape of the injection level dependent lifetime is a result of the surface recombination rate, which is non-linear due to the surfaces moving into inversion with increasing injection level. As a result, the surface recombination rate switches from being limited by electrons to holes. Equations describing the surface saturation current density, J 0s, during this regime are also derived in this work.

Simple liquid models with corrected dielectric constants

PubMed Central

Fennell, Christopher J.; Li, Libo; Dill, Ken A.

2012-01-01

Molecular simulations often use explicit-solvent models. Sometimes explicit-solvent models can give inaccurate values for basic liquid properties, such as the density, heat capacity, and permittivity, as well as inaccurate values for molecular transfer free energies. Such errors have motivated the development of more complex solvents, such as polarizable models. We describe an alternative here. We give new fixed-charge models of solvents for molecular simulations – water, carbon tetrachloride, chloroform and dichloromethane. Normally, such solvent models are parameterized to agree with experimental values of the neat liquid density and enthalpy of vaporization. Here, in addition to those properties, our parameters are chosen to give the correct dielectric constant. We find that these new parameterizations also happen to give better values for other properties, such as the self-diffusion coefficient. We believe that parameterizing fixed-charge solvent models to fit experimental dielectric constants may provide better and more efficient ways to treat solvents in computer simulations. PMID:22397577

Probing the Importance of Charge Flux in Force Field Modeling.

PubMed

Sedghamiz, Elaheh; Nagy, Balazs; Jensen, Frank

2017-08-08

We analyze the conformational dependence of atomic charges and molecular dipole moments for a selection of ∼900 conformations of peptide models of the 20 neutral amino acids. Based on a set of reference density functional theory calculations, we partition the changes into effects due to changes in bond distances, bond angles, and torsional angles and into geometry and charge flux contributions. This allows an assessment of the limitations of fixed charge force fields and indications for how to design improved force fields. The torsional degrees of freedom are the main contribution to conformational changes of atomic charges and molecular dipole moments, but indirect effects due to change in bond distances and angles account for ∼25% of the variation. Charge flux effects dominate for changes in bond distances and are also the main component of the variation in bond angles, while they are ∼25% compared to the geometry variations for torsional degrees of freedom. The geometry and charge flux contributions to some extent produce compensating effects.

The voltage-dependent anion channel as a biological transistor: theoretical considerations.

PubMed

Lemeshko, V V; Lemeshko, S V

2004-07-01

The voltage-dependent anion channel (VDAC) is a porin of the mitochondrial outer membrane with a bell-shaped permeability-voltage characteristic. This porin restricts the flow of negatively charged metabolites at certain non-zero voltages, and thus might regulate their flux across the mitochondrial outer membrane. Here, we have developed a mathematical model illustrating the possibility of interaction between two steady-state fluxes of negatively charged metabolites circulating across the VDAC in a membrane. The fluxes interact by contributing to generation of the membrane electrical potential with subsequent closure of the VDAC. The model predicts that the VDAC might function as a single-molecule biological transistor and amplifier, because according to the obtained calculations a small change in the flux of one pair of different negatively charged metabolites causes a significant modulation of a more powerful flux of another pair of negatively charged metabolites circulating across the same membrane with the VDAC. Such transistor-like behavior of the VDAC in the mitochondrial outer membrane might be an important principle of the cell energy metabolism regulation under some physiological conditions.

An in situ generated carbon as integrated conductive additive for hierarchical negative plate of lead-acid battery

NASA Astrophysics Data System (ADS)

Saravanan, M.; Ganesan, M.; Ambalavanan, S.

2014-04-01

In this work, we report an in situ generated carbon from sugar as additive in the Negative Active Mass (NAM) which enhances the charge-discharge characteristics of the lead-acid cells. In situ formed sugar derived carbon (SDC) with leady oxide (LO) provides a conductive network and excellent protection against NAM irreversible lead sulfation. The effect of SDC and carbon black (CB) added negative plates are characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), galvanostatic charge-discharge, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. The results show that subtle changes in the addition of carbon to NAM led to subsequent changes on the performance during partial-state-of-charge (PSoC) operations in lead-acid cells. Furthermore, SDC added cells exhibit remarkable improvement in the rate capability, active material utilization, cycle performance and charge acceptance compared to that of the conventional CB added cells. The impact of SDC with LO at various synthesis conditions on the electrochemical performance of the negative plate is studied systematically.

Functionalized nanoparticle interactions with polymeric membranes.

PubMed

Ladner, D A; Steele, M; Weir, A; Hristovski, K; Westerhoff, P

2012-04-15

A series of experiments was performed to measure the retention of a class of functionalized nanoparticles (NPs) on porous (microfiltration and ultrafiltration) membranes. The findings impact engineered water and wastewater treatment using membrane technology, characterization and analytical schemes for NP detection, and the use of NPs in waste treatment scenarios. The NPs studied were composed of silver, titanium dioxide, and gold; had organic coatings to yield either positive or negative surface charge; and were between 2 and 10nm in diameter. NP solutions were applied to polymeric membranes composed of different materials and pore sizes (ranging from ≈ 2 nm [3 kDa molecular weight cutoff] to 0.2 μm). Greater than 99% rejection was observed of positively charged NPs by negatively charged membranes even though pore diameters were up to 20 times the NP diameter; thus, sorption caused rejection. Negatively charged NPs were less well rejected, but behavior was dependent not only on surface functionality but on NP core material (Ag, TiO(2), or Au). NP rejection depended more upon NP properties than membrane properties; all of the negatively charged polymeric membranes behaved similarly. The NP-membrane interaction behavior fell into four categories, which are defined and described here. Copyright © 2011 Elsevier B.V. All rights reserved.

Nuclear electromagnetic charge and current operators in Chiral EFT

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

Girlanda, Luca; Marcucci, Laura Elisa; Pastore, Saori

2013-08-01

We describe our method for deriving the nuclear electromagnetic charge and current operators in chiral perturbation theory, based on time-ordered perturbation theory. We then discuss possible strategies for fixing the relevant low-energy constants, from the magnetic moments of the deuteron and of the trinucleons, and from the radiative np capture cross sections, and identify a scheme which, partly relying on {Delta} resonance saturation, leads to a reasonable pattern of convergence of the chiral expansion.

CdTe X-ray detectors under strong optical irradiation

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

Cola, Adriano; Farella, Isabella

2014-11-17

The perturbation behaviour of Ohmic and Schottky CdTe detectors under strong optical pulses is investigated. To this scope, the electric field profiles and the induced charge transients are measured, thus simultaneously addressing fixed and free charges properties, interrelated by one-carrier trapping. The results elucidate the different roles of the contacts and deep levels, both under dark and strong irradiation conditions, and pave the way for the improvement of detector performance control under high X-ray fluxes.

A dynamic parking charge optimal control model under perspective of commuters' evolutionary game behavior

NASA Astrophysics Data System (ADS)

Lin, XuXun; Yuan, PengCheng

2018-01-01

In this research we consider commuters' dynamic learning effect by modeling the trip mode choice behavior from a new perspective of dynamic evolutionary game theory. We explore the behavior pattern of different types of commuters and study the evolution path and equilibrium properties under different traffic conditions. We further establish a dynamic parking charge optimal control (referred to as DPCOC) model to alter commuters' trip mode choice while minimizing the total social cost. Numerical tests show. (1) Under fixed parking fee policy, the evolutionary results are completely decided by the travel time and the only method for public transit induction is to increase the parking charge price. (2) Compared with fixed parking fee policy, DPCOC policy proposed in this research has several advantages. Firstly, it can effectively turn the evolutionary path and evolutionary stable strategy to a better situation while minimizing the total social cost. Secondly, it can reduce the sensitivity of trip mode choice behavior to traffic congestion and improve the ability to resist interferences and emergencies. Thirdly, it is able to control the private car proportion to a stable state and make the trip behavior more predictable for the transportation management department. The research results can provide theoretical basis and decision-making references for commuters' mode choice prediction, dynamic setting of urban parking charge prices and public transit induction.

Surface charge accumulation of solid insulator under nanosecond pulse in vacuum: 3D distribution features and mechanism

NASA Astrophysics Data System (ADS)

Qi, Bo; Gao, Chunjia; Sun, Zelai; Li, Chengrong

2017-11-01

Surface charge accumulation can incur changes in electric field distribution, involved in the electron propagation process, and result in a significant decrease in the surface flashover voltage. The existing 2D surface charge measurement fails to meet the actual needs in real engineering applications that usually adopt the 45° conical frustum insulators. The present research developed a novel 3D measurement platform to capture surface charge distribution on solid insulation under nanosecond pulse in a vacuum. The results indicate that all surface charges are positive under a positive pulse and negative under a negative pulse. Surface charges tend to accumulate more near the upper electrode. Surface charge density increases significantly with the increase in pulse counts and amplitudes. Accumulation of surface charge results in a certain decrease of flashover voltage. Taking consideration of the secondary electron emission for the surface charge accumulation, four materials were obtained to demonstrate the effects on surface charge. Combining the effect incurred by secondary electron emission and the weighty action taken by surface charge accumulation on the flashover phenomena, the discharge mechanism along the insulator surface under nanosecond pulse voltage was proposed.

Lightning Activity Relative to the Microphysical and Kinematic Structure of Storms during a Thunder-Snow Episode on 29-30 November 2006

NASA Astrophysics Data System (ADS)

Emersic, C.; Macgorman, D.; Schuur, T.; Lund, N.; Payne, C.; Bruning, E.

2007-12-01

We have examined lightning activity relative to the microphysical and kinematic structure of a winter thunderstorm complex (a thunder-snow episode) observed east of Norman, Oklahoma during the evening of 29-30 November 2006. Polarimetric radar provided information about the type of particles present in various regions of the storms. The Lightning Mapping Array (LMA) recorded VHF signals produced by developing lightning channels. The times of arrival of these lightning signals across the array were then used to reconstruct the location and structure of lightning, and these reconstructions were overlaid with radar data to examine the relationship between lightning properties and storm particle types. Four storms in this winter complex have been examined. It was inferred from lightning structure that, in their mature stage, all cells we examined had a positive tripole electrical structure (an upper positive charge center, a midlevel negative charge center, and a lower positive charge center). The storms began with lightning activity in the lower dipole (lower positive and midlevel negative regions), but this evolved into lightning activity throughout the tripole structure within approximately 15-20 minutes. In the longer lived storms, the mature stage lasted for approximately 1.5-2 hours. During this stage, the lower positive charge region was situated less than 5 km above ground, the midlevel negative charge region was typically above 5 km, and the upper positive charge region was located at an altitude of less than 10 km in all the storm cells analyzed. The charge regions descended over approximately the last 30 minutes of lightning activity, the lower charge regions eventually reaching ground. This resulted in the loss of the lower positive charge center and the subsequent diminishment of the lower negative charge center. Lightning initiation usually coincided with the edges of regions of high reflectivity and was coincident with the presence of graupel and ice crystals in the lower dipole. Radar data suggest that ice crystals were the dominant charge carriers in the upper positive region.

Lunar Surface Charging during Solar Energetic Particle Events

NASA Astrophysics Data System (ADS)

Halekas, Jasper S.; Delory, G. T.; Mewaldt, R. A.; Lin, R. P.; Fillingim, M. O.; Brain, D. A.; Lee, C. O.; Stubbs, T. J.; Farrell, W. M.; Hudson, M. K.

2006-09-01

The surface of the Moon, not protected by any substantial atmosphere, is directly exposed to the impact of both solar UV and solar wind plasma and energetic particles. This creates a complex lunar electrostatic environment, with the surface typically charging slightly positive in sunlight, and negative in shadow. Observations from the Apollo era and theoretical considerations strongly suggest that surface charging leads to dust electrification and transport, posing a potentially significant hazard for exploration. The most significant charging effects should occur when the Moon is exposed to high-temperature plasmas like those encountered in the terrestrial plasmasheet or in solar storms. We now present evidence for kilovolt-scale negative charging of the shadowed lunar surface during solar energetic particle (SEP) events, utilizing data from the Lunar Prospector Electron Reflectometer (LP ER). We find that SEP events are associated with the most extreme lunar surface charging observed during the LP mission - rivaled only by previously reported charging during traversals of the terrestrial plasmasheet. The largest charging event observed by LP is a 4 kV negative surface potential (as compared to typical values of V) during a SEP event in May 1998. We characterize lunar surface charging during several SEP events, and compare to energetic particle measurements from ACE, Wind, and SOHO in order to determine the relationship between SEP events and extreme lunar surface charging. Space weather events are already considered by NASA to be a significant hazard to lunar exploration, due to high-energy ionizing radiation. Our observations demonstrate that plasma interactions with the lunar surface during SEP events, causing extreme surface charging and potentially significant dust electrification and transport, represent an additional hazard associated with space weather.

Effect of surface material on electrostatic charging of houseflies (Musca domestica L).

PubMed

McGonigle, Daniel F; Jackson, Chris W

2002-04-01

Houseflies (Musca domestica L) accumulated electrostatic charges when walking over clean, uncharged dielectric surfaces. The charges elicited on a walking housefly by a range of materials were quantified, allowing a triboelectric series to be determined relative to M domestica. This ranged from surfaces that charged individuals positively, e.g. Correx (corrugated polypropylene) [.1 (+/- 4.2)pC], to those that applied a negative charge, e.g. clear cast acrylic [-14.9 (+/- 2.9)pC]. Maximum positive and negative charges accumulated by individual M domestica were +73 and -27 pC. Replicate measurements on the same fly and surface showed little variation. Variation between individuals was not related to sex and was not consistent between surfaces. Different materials charged M domestica significantly differently and individual flies had significantly different charging properties. Variation in temperature between 21.3 degrees C and 24.7 degrees C and humidity between 24% and 41% RH significantly affected charge accumulated by M domestica on some surfaces, although further experimentation is needed to confirm this. The implications of this work are discussed in relation to insect trap design and pollination biology.

Physical Origin of Transient Negative Capacitance in a Ferroelectric Capacitor

NASA Astrophysics Data System (ADS)

Chang, Sou-Chi; Avci, Uygar E.; Nikonov, Dmitri E.; Manipatruni, Sasikanth; Young, Ian A.

2018-01-01

Transient negative differential capacitance, the dynamic reversal of transient capacitance in an electrical circuit, is of highly technological and scientific interest since it probes the foundation of ferroelectricity. We study a resistor-ferroelectric capacitor (R -FEC) network through a series of coupled equations based on Kirchhoff's law, electrostatics, and Landau theory. We show that transient negative capacitance (NC) in a R -FEC circuit originates from the mismatch in switching rate between the free charge on the metal plate and the bound charge in a ferroelectric (FE) capacitor during the polarization switching. This transient free charge-polarization mismatch is driven by the negative curvature of the FE free-energy landscape, and it is also analytically shown that a free-energy profile with a negative curvature is the only physical system that can describe transient NC in a R -FEC circuit. Furthermore, transient NC induced by the free charge-polarization mismatch is justified by its dependence on both external resistance and the intrinsic FE viscosity coefficient. The depolarization effect on FE capacitors emphasizes the importance of negative curvature to transient NC and also implies that transient and steady-state NC cannot be observed in a FE capacitor simultaneously. Finally, using the transient NC measurements, a procedure to experimentally determine the viscosity coefficient is presented to provide more insight into the relation between transient NC and the FE free-energy profile.

Noise power spectrum of the fixed pattern noise in digital radiography detectors

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

Kim, Dong Sik, E-mail: dskim@hufs.ac.kr; Kim, Eun

Purpose: The fixed pattern noise in radiography image detectors is caused by various sources. Multiple readout circuits with gate drivers and charge amplifiers are used to efficiently acquire the pixel voltage signals. However, the multiple circuits are not identical and thus yield nonuniform system gains. Nonuniform sensitivities are also produced from local variations in the charge collection elements. Furthermore, in phosphor-based detectors, the optical scattering at the top surface of the columnar CsI growth, the grain boundaries, and the disorder structure causes spatial sensitivity variations. These nonuniform gains or sensitivities cause fixed pattern noise and degrade the detector performance, evenmore » though the noise problem can be partially alleviated by using gain correction techniques. Hence, in order to develop good detectors, comparative analysis of the energy spectrum of the fixed pattern noise is important. Methods: In order to observe the energy spectrum of the fixed pattern noise, a normalized noise power spectrum (NNPS) of the fixed pattern noise is considered in this paper. Since the fixed pattern noise is mainly caused by the nonuniform gains, we call the spectrum the gain NNPS. We first asymptotically observe the gain NNPS and then formulate two relationships to calculate the gain NNPS based on a nonuniform-gain model. Since the gain NNPS values are quite low compared to the usual NNPS, measuring such a low NNPS value is difficult. By using the average of the uniform exposure images, a robust measuring method for the gain NNPS is proposed in this paper. Results: By using the proposed measuring method, the gain NNPS curves of several prototypes of general radiography and mammography detectors were measured to analyze their fixed pattern noise properties. We notice that a direct detector, which is based on the a-Se photoconductor, showed lower gain NNPS than the indirect-detector case, which is based on the CsI scintillator. By comparing the gain NNPS curves of the indirect detectors, we could analyze the scintillator properties depending on the techniques for the scintillator surface processing. Conclusions: A robust measuring method for the NNPS of the fixed pattern noise of a radiography detector is proposed in this paper. The method can measure a stable gain NNPS curve, even though the fixed pattern noise level is quite low. From the measured gain NNPS curves, we can compare and analyze the detector properties in terms of producing the fixed pattern noise.« less

Receptor-Mediated Melanoma Targeting with Radiolabeled α-Melanocyte-Stimulating Hormone: Relevance of the Net Charge of the Ligand.

PubMed

Bapst, Jean-Philippe; Eberle, Alex N

2017-01-01

A majority of melanotic and amelanotic melanomas overexpress melanocortin type 1 receptors (MC1Rs) for α-melanocyte-stimulating hormone. Radiolabeled linear or cyclic analogs of α-MSH have a great potential as diagnostic or therapeutic tools for the management of malignant melanoma. Compounds such as [ 111 In]DOTA-NAP-amide exhibit high affinity for the MC1R in vitro , good tumor uptake in vivo , but they may suffer from relatively high kidney uptake and retention in vivo . We have shown previously that the introduction of negative charges into radiolabeled DOTA-NAP-amide peptide analogs may enhance their excretion and reduce kidney retention. To address the question of where to place negative charges within the ligand, we have extended these studies by designing two novel peptides, Ac-Nle-Asp-His-d-Phe-Arg-Trp-Gly-Lys(DOTA)-d-Asp-d-Asp-OH (DOTA-NAP-d-Asp-d-Asp) with three negative charges at the C -terminal end (overall net charge of the molecule -2) and DOTA-Gly-Tyr(P)-Nle-Asp-His-d-Phe-Arg-Trp-NH 2 (DOTA-Phospho-MSH 2-9 ) with two negative charges in the N -terminal region (net charge -1). The former peptide showed markedly reduced receptor affinity and biological activity by >10-fold compared to DOTA-NAP-amide as reference compound, and the latter peptide displayed similar bioactivity and receptor affinity as the reference compound. The uptake by melanoma tumor tissue of [ 111 In]DOTA-Phospho-MSH 2-9 was 7.33 ± 0.47 %ID/g 4 h after injection, i.e., almost equally high as with [ 111 In]DOTA-NAP-amide. The kidney retention was 2.68 ± 0.18 %ID/g 4 h after injection and hence 44% lower than that of [ 111 In]DOTA-NAP-amide. Over an observation period from 4 to 48 h, the tumor-to-kidney ratio of [ 111 In]DOTA-Phospho-MSH 2-9 was 35% more favorable than that of the reference compound. In a comparison of DOTA-NAP-d-Asp-d-Asp, DOTA-Phospho-MSH 2-9 and DOTA-NAP-amide with five previously published analogs of DOTA-NAP-amide that altogether cover a range of peptides with an overall net charge between +2 and -2, we now demonstrate that a net charge of -1, with the extra negative charges preferably placed in the N -terminal region, has led to the lowest kidney uptake and retention. Charges of +2 or -2 markedly increased kidney uptake and retention. In conclusion, the novel DOTA-Phospho-MSH 2-9 may represent a new lead compound for negatively charged linear MC1R ligands that can be further developed into a clinically relevant melanoma targeting radiopeptide.

Receptor-Mediated Melanoma Targeting with Radiolabeled α-Melanocyte-Stimulating Hormone: Relevance of the Net Charge of the Ligand

PubMed Central

Bapst, Jean-Philippe; Eberle, Alex N.

2017-01-01

A majority of melanotic and amelanotic melanomas overexpress melanocortin type 1 receptors (MC1Rs) for α-melanocyte-stimulating hormone. Radiolabeled linear or cyclic analogs of α-MSH have a great potential as diagnostic or therapeutic tools for the management of malignant melanoma. Compounds such as [111In]DOTA-NAP-amide exhibit high affinity for the MC1R in vitro, good tumor uptake in vivo, but they may suffer from relatively high kidney uptake and retention in vivo. We have shown previously that the introduction of negative charges into radiolabeled DOTA-NAP-amide peptide analogs may enhance their excretion and reduce kidney retention. To address the question of where to place negative charges within the ligand, we have extended these studies by designing two novel peptides, Ac-Nle-Asp-His-d-Phe-Arg-Trp-Gly-Lys(DOTA)-d-Asp-d-Asp-OH (DOTA-NAP-d-Asp-d-Asp) with three negative charges at the C-terminal end (overall net charge of the molecule −2) and DOTA-Gly-Tyr(P)-Nle-Asp-His-d-Phe-Arg-Trp-NH2 (DOTA-Phospho-MSH2-9) with two negative charges in the N-terminal region (net charge −1). The former peptide showed markedly reduced receptor affinity and biological activity by >10-fold compared to DOTA-NAP-amide as reference compound, and the latter peptide displayed similar bioactivity and receptor affinity as the reference compound. The uptake by melanoma tumor tissue of [111In]DOTA-Phospho-MSH2-9 was 7.33 ± 0.47 %ID/g 4 h after injection, i.e., almost equally high as with [111In]DOTA-NAP-amide. The kidney retention was 2.68 ± 0.18 %ID/g 4 h after injection and hence 44% lower than that of [111In]DOTA-NAP-amide. Over an observation period from 4 to 48 h, the tumor-to-kidney ratio of [111In]DOTA-Phospho-MSH2-9 was 35% more favorable than that of the reference compound. In a comparison of DOTA-NAP-d-Asp-d-Asp, DOTA-Phospho-MSH2-9 and DOTA-NAP-amide with five previously published analogs of DOTA-NAP-amide that altogether cover a range of peptides with an overall net charge between +2 and −2, we now demonstrate that a net charge of −1, with the extra negative charges preferably placed in the N-terminal region, has led to the lowest kidney uptake and retention. Charges of +2 or −2 markedly increased kidney uptake and retention. In conclusion, the novel DOTA-Phospho-MSH2-9 may represent a new lead compound for negatively charged linear MC1R ligands that can be further developed into a clinically relevant melanoma targeting radiopeptide. PMID:28491052

Production cost analysis of Euphorbia lathyris. Final report

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

Mendel, D.A.; Schooley, F.A.; Dickenson, R.L.

1979-08-01

The purpose of SRI's study was to estimate the costs of producing Euphorbia in commercial quantities in five regions of the United States, which include both irrigated and nonirrigated areas. The study assumed that a uniform crop yield could be achieved in the five regions by varying the quantities of production inputs. Therefore, the production costs estimates, which are based on fourth quarter 1978 dollars, include both fixed and variable costs for each region. Doane's Machinery Custom Rates for 1978 were used to estimate all variable costs except materials, which were estimated separately. Custom rates are determined by members ofmore » the Doane Countywide Farm Panel, a group of farmers specifically selected to represent the various sizes and types of commercial farms found throughout the country. The rates reported are the most recent rates the panel members had either paid, charged, or known for certain a second party had paid or charged. Custom rates for any particular operation include equipment operating costs (fuel, lubrication, and repairs), equipment ownership costs (depreciation, taxes, interest), as well as a labor charge for the operator. Custom rates are regionally specific and thereby assist the accuracy of this analysis. Fixed costs include land, management, and transportation of the plant material to a conversion facility. When appropriate, fixed costs were regionally specific. Changes in total production costs over future time periods were not addressed. The total estimated production costs of Euphorbia in each region were compared with production costs for corn and alfalfa in the same regions. Finally, the effects on yield and costs of changes in the production inputs were estimated.« less

Advances in Nonlinear Non-Scaling FFAGs

NASA Astrophysics Data System (ADS)

Johnstone, C.; Berz, M.; Makino, K.; Koscielniak, S.; Snopok, P.

Accelerators are playing increasingly important roles in basic science, technology, and medicine. Ultra high-intensity and high-energy (GeV) proton drivers are a critical technology for accelerator-driven sub-critical reactors (ADS) and many HEP programs (Muon Collider) but remain particularly challenging, encountering duty cycle and space-charge limits in the synchrotron and machine size concerns in the weaker-focusing cyclotrons; a 10-20 MW proton driver is not presently considered technically achievable with conventional re-circulating accelerators. One, as-yet, unexplored re-circulating accelerator, the Fixed-field Alternating Gradient or FFAG, is an attractive alternative to the other approaches to a high-power beam source. Its strong focusing optics can mitigate space charge effects and achieve higher bunch charges than are possible in a cyclotron, and a recent innovation in design has coupled stable tunes with isochronous orbits, making the FFAG capable of fixed-frequency, CW acceleration, as in the classical cyclotron but beyond their energy reach, well into the relativistic regime. This new concept has been advanced in non-scaling nonlinear FFAGs using powerful new methodologies developed for FFAG accelerator design and simulation. The machine described here has the high average current advantage and duty cycle of the cyclotron (without using broadband RF frequencies) in combination with the strong focusing, smaller losses, and energy variability that are more typical of the synchrotron. The current industrial and medical standard is a cyclotron, but a competing CW FFAG could promote a shift in this baseline. This paper reports on these new advances in FFAG accelerator technology and presents advanced modeling tools for fixed-field accelerators unique to the code COSY INFINITY.1

A strategy for enhancing financial performance: a study of general acute care hospitals in South Korea.

PubMed

Choi, Mankyu; Lee, Keon-Hyung

2008-01-01

In this study, the determinants of hospital profitability were evaluated using a sample of 142 hospitals that had undergone hospital standardization inspections by the South Korea Hospital Association over the 4-year period from 1998 to 2001. The measures of profitability used as dependent variables in this study were pretax return on assets, after-tax return on assets, basic earning power, pretax operating margin, and after-tax operating margin. Among those determinants, it was found that ownership type, teaching status, inventory turnover, and the average charge per adjusted inpatient day positively and statistically significantly affected all 5 of these profitability measures. However, the labor expenses per adjusted inpatient day and administrative expenses per adjusted inpatient day negatively and statistically significantly affected all 5 profitability measures. The debt ratio negatively and statistically significantly affected all 5 profitability measures, with the exception of basic earning power. None of the market factors assessed were shown to significantly affect profitability. In conclusion, the results of this study suggest that the profitability of hospitals can be improved despite deteriorating external environmental conditions by facilitating the formation of sound financial structures with optimal capital supplies, optimizing the management of total assets with special emphasis placed on inventory management, and introducing efficient control of fixed costs including labor and administrative expenses.

Extracting dielectric fixed charge density on highly doped crystalline-silicon surfaces using photoconductance measurements

NASA Astrophysics Data System (ADS)

To, A.; Hoex, B.

2017-11-01

A novel method for the extraction of fixed interface charge, Qf, and the surface recombination parameters, Sn0 and Sp0, from the injection-level dependent effective minority carrier lifetime measurements is presented. Unlike conventional capacitance-voltage measurements, this technique can be applied to highly doped surfaces provided the surface carrier concentration transitions into strong depletion or inversion with increased carrier injection. By simulating the injection level dependent Auger-corrected inverse lifetime curve of symmetrically passivated and diffused samples after sequential annealing and corona charging, it was revealed that Qf, Sn0, and Sp0 have unique signatures. Therefore, these important electronic parameters, in some instances, can independently be resolved. Furthermore, it was shown that this non-linear lifetime behaviour is exhibited on both p-type and n-type diffused inverted surfaces, by demonstrating the approach with phosphorous diffused n+pn+ structures and boron diffused p+np+ structures passivated with aluminium oxide (AlOx) and silicon nitride, respectively (SiNx). The results show that the approximation of a mid-gap Shockley-Read-Hall defect level with equal capture cross sections is able to, in the samples studied in this work, reproduce the observed injection level dependent lifetime behaviour.

The entrance channel effects on the deexcitation ways of the same compound nucleus at a fixed excitation energy

NASA Astrophysics Data System (ADS)

Anastasi, A.; Mandaglio, G.; Curciarello, F.; Nasirov, A. K.; Fazio, G.; Giardina, G.

2018-05-01

The investigation of various properties of deexcitation of the same 220Th compound nucleus (CN), formed by the different mass (charge) asymmetric 16O+204Pb, 40Ar+180Hf, 82Se+138Ba and 96Zr+124Sn reactions is presented. The effective fission barrier < B fis > value, as a function of the excitation energy {E}CN* , determined for each intermediate excited nucleus reached along the deexcitation cascade of the CN obtained by the four considered reactions is strongly sensitive to the various orbital angular momentum L=ℓℏ distributions of CN formed with the same excitation energy {E}CN* by the various entrance channels. Therefore, the competition between the fission and evaporation of light particles (neutron, proton, and α-particle) processes along the deexcitation cascade of CN is dependent on the orbital angular momentum distribution of CN. In fact, the ratio between the evaporation residue cross sections obtained when also the charged particles are emitted and the ones obtained after neutron emission only for the same CN with a fixed excitation energy {E}CN* is sensitive to the mass (charge) asymmetry of the entrance channel.

Drude-type conductivity of charged sphere colloidal crystals: Density and temperature dependence

NASA Astrophysics Data System (ADS)

Medebach, Martin; Jordán, Raquel Chuliá; Reiber, Holger; Schöpe, Hans-Joachim; Biehl, Ralf; Evers, Martin; Hessinger, Dirk; Olah, Julianna; Palberg, Thomas; Schönberger, Ernest; Wette, Patrick

2005-09-01

We report on extensive measurements in the low-frequency limit of the ac conductivity of colloidal fluids and crystals formed from charged colloidal spheres suspended in de-ionized water. Temperature was varied in a range of 5°C<Θ<35°C and the particle number density n between 0.2 and 25μm-3 for the larger, respectively, 2.75 and 210μm-3 for the smaller of two investigated species. At fixed Θ the conductivity increased linearly with increasing n without any significant change at the fluid-solid phase boundary. At fixed n it increased with increasing Θ and the increase was more pronounced for larger n. Lacking a rigorous electrohydrodynamic treatment for counterion-dominated systems we describe our data with a simple model relating to Drude's theory of metal conductivity. The key parameter is an effectively transported particle charge or valence Z*. All temperature dependencies other than that of Z* were taken from literature. Within experimental resolution Z* was found to be independent of n irrespective of the suspension structure. Interestingly, Z* decreases with temperature in near quantitative agreement with numerical calculations.

Asymptotic charges cannot be measured in finite time

DOE PAGES

Bousso, Raphael; Chandrasekaran, Venkatesa; Halpern, Illan F.; ...

2018-02-28

To study quantum gravity in asymptotically flat spacetimes, one would like to understand the algebra of observables at null infinity. Here we show that the Bondi mass cannot be observed in finite retarded time, and so is not contained in the algebra on any finite portion of I +. This follows immediately from recently discovered asymptotic entropy bounds. We verify this explicitly, and we find that attempts to measure a conserved charge at arbitrarily large radius in fixed retarded time are thwarted by quantum fluctuations. We comment on the implications of our results to flat space holography and the BMSmore » charges at I +.« less

Asymptotic charges cannot be measured in finite time

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

Bousso, Raphael; Chandrasekaran, Venkatesa; Halpern, Illan F.

To study quantum gravity in asymptotically flat spacetimes, one would like to understand the algebra of observables at null infinity. Here we show that the Bondi mass cannot be observed in finite retarded time, and so is not contained in the algebra on any finite portion of I +. This follows immediately from recently discovered asymptotic entropy bounds. We verify this explicitly, and we find that attempts to measure a conserved charge at arbitrarily large radius in fixed retarded time are thwarted by quantum fluctuations. We comment on the implications of our results to flat space holography and the BMSmore » charges at I +.« less

Sulfogalactosylglycerolipid is involved in human gamete interaction.

PubMed

Weerachatyanukul, W; Rattanachaiyanont, M; Carmona, E; Furimsky, A; Mai, A; Shoushtarian, A; Sirichotiyakul, S; Ballakier, H; Leader, A; Tanphaichitr, N

2001-12-01

Recent results from our laboratory have revealed the role of sulfogalactosylglycerolipid (SGG) in mouse sperm-zona pellucida (ZP) binding. In this report, we demonstrated the presence of SGG in Percoll-gradient centrifuged (PGC) human sperm by high performance thin layer chromatography with orcinol and Azure A staining, specific for glycolipids and sulfolipids, respectively. SGG in human PGC sperm was quantified by its affinity to Azure A to be 12-15 mol% of sperm lipids. Indirect immunofluorescence revealed that SGG existed on both live and aldehyde fixed human sperm in the head region. Pretreatment of human PGC sperm with affinity purified antiSGG Fab markedly inhibited sperm binding to the ZP in a concentration dependent manner, without any changes in the spontaneous acrosome rate or sperm motility parameters. Fluorescently labeled SGG liposomes also bound uniformly to isolated human ZP, while fluorescently labeled galactosylglycerolipid (GG, SGG's parental lipid) or phosphatidylserine (PS, negatively charged like SGG) liposomes did not. All of these results suggested the role of human sperm SGG in ZP binding. Copyright 2001 Wiley-Liss, Inc.

Investigating protein-protein interaction surfaces using a reduced stereochemical and electrostatic model.

PubMed

Warwicker, J

1989-03-20

A method of calculating the electrostatic potential energy between two molecules, using finite difference potential, is presented. A reduced charge set is used so that the interaction energy can be calculated as the two static molecules explore their full six-dimensional configurational space. The energies are contoured over surfaces fixed to each molecule with an interactive computer graphics program. For two crystal structures (trypsin-trypsin inhibitor and anti-lysozyme Fab-lysozyme), it is found that the complex corresponds to highly favourable interacting regions in the contour plots. These matches arise from a small number of protruding basic residues interacting with enhanced negative potential in each case. The redox pair cytochrome c peroxidase-cytochrome c exhibits an extensive favourably interacting surface within which a possible electron transfer complex may be defined by an increased electrostatic complementarity, but a decreased electrostatic energy. A possible substrate transfer configuration for the glycolytic enzyme pair glyceraldehyde phosphate dehydrogenase-phosphoglycerate kinase is presented.

Impact of oxygen precursor flow on the forward bias behavior of MOCVD-Al2O3 dielectrics grown on GaN

NASA Astrophysics Data System (ADS)

Chan, Silvia H.; Bisi, Davide; Liu, Xiang; Yeluri, Ramya; Tahhan, Maher; Keller, Stacia; DenBaars, Steven P.; Meneghini, Matteo; Mishra, Umesh K.

2017-11-01

This paper investigates the effects of the oxygen precursor flow supplied during metalorganic chemical vapor deposition (MOCVD) of Al2O3 films on the forward bias behavior of Al2O3/GaN metal-oxide-semiconductor capacitors. The low oxygen flow (100 sccm) delivered during the in situ growth of Al2O3 on GaN resulted in films that exhibited a stable capacitance under forward stress, a lower density of stress-generated negative fixed charges, and a higher dielectric breakdown strength compared to Al2O3 films grown under high oxygen flow (480 sccm). The low oxygen grown Al2O3 dielectrics exhibited lower gate current transients in stress/recovery measurements, providing evidence of a reduced density of trap states near the GaN conduction band and an enhanced robustness under accumulated gate stress. This work reveals oxygen flow variance in MOCVD to be a strategy for controlling the dielectric properties and performance.

Electron kinetics at the plasma interface

NASA Astrophysics Data System (ADS)

Bronold, Franz Xaver; Fehske, Holger; Pamperin, Mathias; Thiessen, Elena

2018-05-01

The most fundamental response of an ionized gas to a macroscopic object is the formation of the plasma sheath. It is an electron depleted space charge region, adjacent to the object, which screens the object's negative charge arising from the accumulation of electrons from the plasma. The plasma sheath is thus the positively charged part of an electric double layer whose negatively charged part is inside the wall. In the course of the Transregional Collaborative Research Center SFB/TRR24 we investigated, from a microscopic point of view, the elementary charge transfer processes responsible for the electric double layer at a floating plasma-wall interface and made first steps towards a description of the negative part of the layer inside the wall. Below we review our work in a colloquial manner, describe possible extensions, and identify key issues which need to be resolved to make further progress in the understanding of the electron kinetics across plasma-wall interfaces. Contribution to the Topical Issue "Fundamentals of Complex Plasmas", edited by Jürgen Meichsner, Michael Bonitz, Holger Fehske, Alexander Piel.

Characteristics of space charge formed in a laminated LDPE/EVA dielectric under DC stress

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

Tanaka, Toshikatsu; Kisanuki, Osamu; Sakata, Masataka

1996-12-31

A laser-induced pressure pulse (LIPP) method was used for measuring the space charge distribution of LDPE/EVA laminate dielectrics under dc stress. The constant voltage up to {+-}20 kV was applied to a side of the laminates of 0.5 mm thickness for 30 minutes. The other side is grounded. When the amount of space charge was measured by LIPP, both sides were virtually grounded. Space charge built up in or near the interface between LDPE and EVA was mainly investigated. Positive and negative voltage was applied to the side of LDPE in the laminates. It was clarified that the space chargemore » was larger in case of LDPE negatively biased than in case of LDPE positively biased. The density of the space charge ranged around 1 nC/mm{sup 3}. The formation of interfacial space charge is analyzed.« less

Charge Effects on the Efflorescence in Single Levitated Droplets.

PubMed

Hermann, Gunter; Zhang, Yan; Wassermann, Bernhard; Fischer, Henry; Quennet, Marcel; Rühl, Eckart

2017-09-14

The influence of electrical excess charges on the crystallization from supersaturated aqueous sodium chloride solutions is reported. This is accomplished by efflorescence studies on single levitated microdroplets using optical and electrodynamic levitation. Specifically, a strong increase in efflorescence humidity is observed as a function of the droplet's negative excess charge, ranging up to -2.1 pC, with a distinct threshold behavior, increasing the relative efflorescence humidity, at which spontaneous nucleation occurs, from 44% for the neutral microparticle to 60%. These findings are interpreted by using molecular dynamics simulations for determining plausible structural patterns located near the particle surface that could serve as suitable precursors for the formation of critical clusters overcoming the nucleation barrier. These results, facilitating heterogeneous nucleation in the case of negatively charged microparticles, are compared to recent work on charge-induced nucleation of neat supercooled water, where a distinctly different nucleation behavior as a function of droplet charge has been observed.

Concentration Dependent Effects of Bovine Serum Albumin on Graphene Oxide Colloidal Stability in Aquatic Environment.

PubMed

Sun, Binbin; Zhang, Yinqing; Chen, Wei; Wang, Kunkun; Zhu, Lingyan

2018-06-22

The impacts of a model globular protein (bovine serum albumin, BSA) on aggregation kinetics of graphene oxide (GO) in aquatic environment were investigated through time-resolved dynamic light scattering at pH 5.5. Aggregation kinetics of GO without BSA as a function of electrolyte concentrations (NaCl, MgCl 2 , and CaCl 2 ) followed the traditional Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, and the critical coagulation concentration (CCC) was 190, 5.41, and 1.61 mM, respectively. As BSA was present, it affected the GO stability in a concentration dependent manner. At fixed electrolyte concentrations below the CCC values, for example 120 mM NaCl, the attachment efficiency of GO increased from 0.08 to 1, then decreased gradually and finally reached up to zero as BSA concentration increased from 0 to 66.5 mg C/L. The low-concentration BSA depressed GO stability mainly due to electrostatic binding between the positively charged lysine groups of BSA and negatively charged groups of GO, as well as double layer compression effect. With the increase of BSA concentration, more and more BSA molecules were adsorbed on GO, leading to strong steric repulsion which finally predominated and stabilized the GO. These results provided significant information about the concentration dependent effects of natural organic matters on GO stability under environmentally relevant conditions.

Structural Basis of the High Affinity Interaction between the Alphavirus Nonstructural Protein-3 (nsP3) and the SH3 Domain of Amphiphysin-2.

PubMed

Tossavainen, Helena; Aitio, Olli; Hellman, Maarit; Saksela, Kalle; Permi, Perttu

2016-07-29

We show that a peptide from Chikungunya virus nsP3 protein spanning residues 1728-1744 binds the amphiphysin-2 (BIN1) Src homology-3 (SH3) domain with an unusually high affinity (Kd 24 nm). Our NMR solution complex structure together with isothermal titration calorimetry data on several related viral and cellular peptide ligands reveal that this exceptional affinity originates from interactions between multiple basic residues in the target peptide and the extensive negatively charged binding surface of amphiphysin-2 SH3. Remarkably, these arginines show no fixed conformation in the complex structure, indicating that a transient or fluctuating polyelectrostatic interaction accounts for this affinity. Thus, via optimization of such dynamic electrostatic forces, viral peptides have evolved a superior binding affinity for amphiphysin-2 SH3 compared with typical cellular ligands, such as dynamin, thereby enabling hijacking of amphiphysin-2 SH3-regulated host cell processes by these viruses. Moreover, our data show that the previously described consensus sequence PXRPXR for amphiphysin SH3 ligands is inaccurate and instead define it as an extended Class II binding motif PXXPXRpXR, where additional positive charges between the two constant arginine residues can give rise to extraordinary high SH3 binding affinity. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

An anisotropic hydrogel with electrostatic repulsion between cofacially aligned nanosheets

NASA Astrophysics Data System (ADS)

Liu, Mingjie; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Takata, Masaki; Aida, Takuzo

2015-01-01

Machine technology frequently puts magnetic or electrostatic repulsive forces to practical use, as in maglev trains, vehicle suspensions or non-contact bearings. In contrast, materials design overwhelmingly focuses on attractive interactions, such as in the many advanced polymer-based composites, where inorganic fillers interact with a polymer matrix to improve mechanical properties. However, articular cartilage strikingly illustrates how electrostatic repulsion can be harnessed to achieve unparalleled functional efficiency: it permits virtually frictionless mechanical motion within joints, even under high compression. Here we describe a composite hydrogel with anisotropic mechanical properties dominated by electrostatic repulsion between negatively charged unilamellar titanate nanosheets embedded within it. Crucial to the behaviour of this hydrogel is the serendipitous discovery of cofacial nanosheet alignment in aqueous colloidal dispersions subjected to a strong magnetic field, which maximizes electrostatic repulsion and thereby induces a quasi-crystalline structural ordering over macroscopic length scales and with uniformly large face-to-face nanosheet separation. We fix this transiently induced structural order by transforming the dispersion into a hydrogel using light-triggered in situ vinyl polymerization. The resultant hydrogel, containing charged inorganic structures that align cofacially in a magnetic flux, deforms easily under shear forces applied parallel to the embedded nanosheets yet resists compressive forces applied orthogonally. We anticipate that the concept of embedding anisotropic repulsive electrostatics within a composite material, inspired by articular cartilage, will open up new possibilities for developing soft materials with unusual functions.

An anisotropic hydrogel with electrostatic repulsion between cofacially aligned nanosheets.

PubMed

Liu, Mingjie; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Takata, Masaki; Aida, Takuzo

2015-01-01

Machine technology frequently puts magnetic or electrostatic repulsive forces to practical use, as in maglev trains, vehicle suspensions or non-contact bearings. In contrast, materials design overwhelmingly focuses on attractive interactions, such as in the many advanced polymer-based composites, where inorganic fillers interact with a polymer matrix to improve mechanical properties. However, articular cartilage strikingly illustrates how electrostatic repulsion can be harnessed to achieve unparalleled functional efficiency: it permits virtually frictionless mechanical motion within joints, even under high compression. Here we describe a composite hydrogel with anisotropic mechanical properties dominated by electrostatic repulsion between negatively charged unilamellar titanate nanosheets embedded within it. Crucial to the behaviour of this hydrogel is the serendipitous discovery of cofacial nanosheet alignment in aqueous colloidal dispersions subjected to a strong magnetic field, which maximizes electrostatic repulsion and thereby induces a quasi-crystalline structural ordering over macroscopic length scales and with uniformly large face-to-face nanosheet separation. We fix this transiently induced structural order by transforming the dispersion into a hydrogel using light-triggered in situ vinyl polymerization. The resultant hydrogel, containing charged inorganic structures that align cofacially in a magnetic flux, deforms easily under shear forces applied parallel to the embedded nanosheets yet resists compressive forces applied orthogonally. We anticipate that the concept of embedding anisotropic repulsive electrostatics within a composite material, inspired by articular cartilage, will open up new possibilities for developing soft materials with unusual functions.

Transmission of low-energy negative ions through insulating nanocapillaries

NASA Astrophysics Data System (ADS)

Zhang, Qi; Liu, Zhonglin; Li, Pengfei; Jin, Bo; Song, Guangyin; Jin, Dingkun; Niu, Ben; Wei, Long; Ha, Shuai; Xie, Yiming; Ma, Yue; Wan, Chengliang; Cui, Ying; Zhou, Peng; Zhang, Hongqiang; Chen, Ximeng

2018-04-01

A simulation is performed to study the transmission of low-energy C l- ions through A l2O3 nanocapillaries. For the trajectory simulations, there are several processes involved: the image forces induced by the projectile; the electrostatic force from the deposited charges; the scattering from the inner surface and charge exchange. The simulation reproduces the main features of the experiments; i.e., the double peak structure in the transmitted angular distribution and the transmitted fractions of C l- , C l+ , and C l0 were found in the charge state distribution. The transmitted C l- ions are centered around the beam direction while the transmitted fractions of C l0 and C l+ are centered around the tilt angles. The role of the deposited charge is also studied by simulations. With the deposited charge, it is found that C l- is dominant in the transmission and the majority of the ions, centered around the tilt angle, are mainly from the single deflection by the negative charge patches on the inner surfaces of the capillaries, and only a few directly transmitted C l- ions are centered around the incident direction. There are also a few transmitted fractions of C l0 and C l+ from close surface scatterings. In the case that there are no negative charge patches, the simulation agrees with the experiment in detail: The majority of the directly transmitted C l- ions are centered around the incident direction while only a few scattered C l- ions are centered around the tilt angle from the single close collisions with the inner surfaces of the capillaries. There is a portion, comparable to the transmitted fraction of C l- , of the transmitted fractions of C l0 and C l+ , centered around the tilt angle, from the single scatterings with the inner surfaces of the capillaries. This confirms that at the present experimental conditions there are most probably no negative charge patches formed to guide the negative ions through insulating A l2O3 nanocapillaries.

Lysozyme adsorption in pH-responsive hydrogel thin-films: the non-trivial role of acid-base equilibrium.

PubMed

Narambuena, Claudio F; Longo, Gabriel S; Szleifer, Igal

2015-09-07

We develop and apply a molecular theory to study the adsorption of lysozyme on weak polyacid hydrogel films. The theory explicitly accounts for the conformation of the network, the structure of the proteins, the size and shape of all the molecular species, their interactions as well as the chemical equilibrium of each titratable unit of both the protein and the polymer network. The driving forces for adsorption are the electrostatic attractions between the negatively charged network and the positively charged protein. The adsorption is a non-monotonic function of the solution pH, with a maximum in the region between pH 8 and 9 depending on the salt concentration of the solution. The non-monotonic adsorption is the result of increasing negative charge of the network with pH, while the positive charge of the protein decreases. At low pH the network is roughly electroneutral, while at sufficiently high pH the protein is negatively charged. Upon adsorption, the acid-base equilibrium of the different amino acids of the protein shifts in a nontrivial fashion that depends critically on the particular kind of residue and solution composition. Thus, the proteins regulate their charge and enhance adsorption under a wide range of conditions. In particular, adsorption is predicted above the protein isoelectric point where both the solution lysozyme and the polymer network are negatively charged. This behavior occurs because the pH in the interior of the gel is significantly lower than that in the bulk solution and it is also regulated by the adsorption of the protein in order to optimize protein-gel interactions. Under high pH conditions we predict that the protein changes its charge from negative in the solution to positive within the gel. The change occurs within a few nanometers at the interface of the hydrogel film. Our predictions show the non-trivial interplay between acid-base equilibrium, physical interactions and molecular organization under nanoconfined conditions, which leads to non-trivial adsorption behavior that is qualitatively different from what would be predicted from the state of the proteins in the bulk solution.

A new biphasic osteoinductive calcium composite material with a negative Zeta potential for bone augmentation

PubMed Central

Smeets, Ralf; Kolk, Andreas; Gerressen, Marcus; Driemel, Oliver; Maciejewski, Oliver; Hermanns-Sachweh, Benita; Riediger, Dieter; Stein, Jamal M

2009-01-01

The aim of the present study was to analyze the osteogenic potential of a biphasic calcium composite material (BCC) with a negative surface charge for maxillary sinus floor augmentation. In a 61 year old patient, the BCC material was used in a bilateral sinus floor augmentation procedure. Six months postoperative, a bone sample was taken from the augmented regions before two titanium implants were inserted at each side. We analyzed bone neoformation by histology, bone density by computed tomography, and measured the activity of voltage-activated calcium currents of osteoblasts and surface charge effects. Control orthopantomograms were carried out five months after implant insertion. The BCC was biocompatible and replaced by new mineralized bone after being resorbed completely. The material demonstrated a negative surface charge (negative Zeta potential) which was found to be favorable for bone regeneration and osseointegration of dental implants. PMID:19523239

Fixed Junction Light Emitting Electrochemical Cells based on Polymerizable Ionic Liquids

NASA Astrophysics Data System (ADS)

Brown, Erin; Limanek, Austin; Bauman, James; Leger, Janelle

Organic photovoltaic (OPV) devices are of interest due to ease of fabrication, which increases their cost-effectiveness. OPV devices based on fixed-junction light emitting electrochemical cells (LECs) in particular have shown promising results. LECs are composed of a layer of polymer semiconductor blended with a salt sandwiched between two electrodes. As a forward bias is applied, the ions within the polymer separate, migrate to the electrodes, and enable electrochemical doping, thereby creating a p-n junction analog. In a fixed junction device, the ions are immobilized after the desired distribution has been established, allowing for operation under reverse bias conditions. Fixed junctions can be established using various techniques, including chemically by mixing polymerizable salts that will bond to the polymer under a forward bias. Previously we have demonstrated the use of the polymerizable ionic liquid allyltrioctylammonium allysulfonate (ATOAAS) as an effective means of creating a chemically fixed junction in an LEC. Here we present the application of this approach to the creation of photovoltaic devices. Devices demonstrate higher open circuit voltages, faster charging, and an overall improved device performance over previous chemically-fixed junction PV devices.

Modeling carbonaceous particle formation in an argon graphite cathode dc discharge

NASA Astrophysics Data System (ADS)

Michau, A.; Lombardi, G.; Colina Delacqua, L.; Redolfi, M.; Arnas, C.; Bonnin, X.; Hassouni, K.

2010-12-01

We develop a model for the nucleation, growth and transport of carbonaceous dust particles in a non-reactive gas dc discharge where the carbon source is provided by cathode sputtering. We consider only the initial phase of the discharge when the dust charge density remains small with respect to the electron density. We find that an electric field reversal at the entrance of the negative glow region promotes trapping of negatively charged clusters and dust particles, confining them for long times in the plasma and favoring molecular growth. An essential ingredient for this process is electron attachment, which negatively charges the initially neutral clusters. We perform sensitivity studies on several number parameters: size of the largest molecular edifice, sticking coefficient, etc.

Nanoparticle coagulation in fractionally charged and charge fluctuating dusty plasmas

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

Nunomura, Shota; Kondo, Michio; Shiratani, Masaharu

2008-08-15

The kinetics of nanoparticle coagulation has been studied in fractionally charged and charge fluctuating dusty plasmas. The coagulation occurs when the mutual collision frequency among nanoparticles exceeds their charging and decharging/neutralization frequency. Interestingly, the coagulation is suppressed while a fraction (several percent) of nanoparticles are negatively charged in a plasma, in which stochastic charging plays an important role. A model is developed to predict a phase diagram of the coagulation and its suppression.

Managing technology licensing for stochastic R&D: from the perspective of an enterprise information system

NASA Astrophysics Data System (ADS)

Hong, Xianpei; Zhao, Dan; Wang, Zongjun

2016-10-01

Enterprise information technology (IT) plays an important role in technology innovation management for high-tech enterprises. However, to date most studies on enterprise technology innovation have assumed that the research and development (R&D) outcome is certain. This assumption does not always hold in practice. Motivated by the current practice of some IT industries, we establish a three-stage duopoly game model, including the R&D stage, the licensing stage and the output stage, to investigate the influence of bargaining power and technology spillover on the optimal licensing policy for the innovating enterprise when the outcome of R&D is uncertain. Our results demonstrate that (1) if the licensor has low (high) bargaining power, fixed-fee (royalty) licensing is always superior to royalty (fixed-fee) licensing to the licensor regardless of technology spillover; (2) if the licensor has moderate bargaining power and technology spillover is low (high) as well, fixed-fee (royalty) licensing is superior to royalty (fixed-fee) licensing; (3) under two-part tariff licensing and the assumption of licensors with full bargaining power, if a negative prepaid fixed fee is not allowed, two-part tariff licensing is equivalent to royalty licensing which is the optimal licensing policy; if negative prepaid fixed fee is allowed, the optimal policy is two-part tariff licensing.

A Brief 30-Year Review: Research Highlights from Lightning Mapping Systems 1970-2000

NASA Astrophysics Data System (ADS)

MacGorman, D. R.

2016-12-01

Modern lightning mapping began in the 1970s, the decade in which VHF mapping systems, acoustic mapping systems, and ground strike locating systems were introduced. Adding GPS synchronization of VHF systems in the late 1990s enabled real-time VHF mapping systems to be deployed more extensively. Data these systems provided by 2000 revolutionized our understanding of how storms produce lightning. Among key results: Electrostatics, not electrodynamics, governs where lightning is initiated and where it propagates, contrary to early expectations. Lightning is initiated in a region of large electric field magnitude, typically between a positive charge region and a negative charge region. The geometry of a storm's charge regions governs the spatial extent of each end of the flash. The flash initially propagates bidirectionally toward the two charge regions that initiated it, and once it reaches the charge regions and maximizes the ambient potential difference spanned by the flash structure, it extends through each charge region's ambient electric potential well until the total electric field magnitude at the ends of the flash drops below the threshold for continued propagation. The typical charge distribution producing a cloud-to-ground flash is a region of charge of the polarity being lowered to ground, above a lesser amount of charge of the opposite polarity; the lower region has too little charge to capture the downward propagating channel. Contrary to previous understanding, naturally occurring cloud-to-ground lightning often lowers positive charge to ground, instead of the usual negative charge, in several situations, including winter storms, stratiform precipitation regions, some severe storms, and storms on the High Plains of the United States. The reason cloud-to-ground activity in some storms is dominated by flashes that lower positive charge to ground is that the polarity of the main charge regions in those storms is inverted from the usual polarity, with the main mid-level charge being positive and the main upper-level charge being negative. This strongly implies that the dominant non-inductive electrification mechanism is inverted in those storms, probably because the liquid water content in the mixed phase region is larger than in most storms.

Investigation of Dusts Effect and Negative Ion in DC Plasmas by Electric Probes

NASA Astrophysics Data System (ADS)

Oh, Hye Taek; Kang, Inje; Bae, Min-Keun; Park, Insun; Lee, Seunghwa; Jeong, Seojin; Chung, Kyu-Sun

2017-10-01

Dust is typically negatively charged by electron attachment whose thermal velocities are fast compared to that of the heavier ions. The negatively charged particles can play a role of negative ions which affect the quasi-neutrality of background plasma. To investigate effect of metal dusts and negative ion on plasma and materials, metal dusts are injected into background Ar plasma which is generated by tungsten filament using dust dispenser on Cubical Plasma Device (CPD). The CPD has following conditions: size =24x24x24cm3, plasma source =DC filament plasma (ne 1x10x1010, Te 2eV), background gas =Ar, dusts =tungsten powder (diameter 1.89micron). The dust dispenser is developed to quantitate of metal dust by ultrasonic transducer. Electronegative plasmas are generated by adding O2 + Ar plasma to compare negative ion and dust effect. A few grams of micron-sized dusts are placed in the dust dispenser which is located at the upper side of the Cubical Plasma Device. The falling particles by dust dispenser are mainly charged up by the collection of the background plasma. The change in parameters due to negative ion production are characterized by measuring the floating and plasma potential, electron temperature and negative ion density using electric probes.

BFV-BRST analysis of equivalence between noncommutative and ordinary gauge theories

NASA Astrophysics Data System (ADS)

Dayi, O. F.

2000-05-01

Constrained hamiltonian structure of noncommutative gauge theory for the gauge group /U(1) is discussed. Constraints are shown to be first class, although, they do not give an Abelian algebra in terms of Poisson brackets. The related BFV-BRST charge gives a vanishing generalized Poisson bracket by itself due to the associativity of /*-product. Equivalence of noncommutative and ordinary gauge theories is formulated in generalized phase space by using BFV-BRST charge and a solution is obtained. Gauge fixing is discussed.

The strange sea density and charm production in deep inelastic charged current processes

NASA Astrophysics Data System (ADS)

Glück, M.; Kretzer, S.; Reya, E.

1996-02-01

Charm production as related to the determination of the strange sea density in deep inelastic charged current processes is studied predominantly in the framework of the overlineMS fixed flavor factorization scheme. Perturbative stability within this formalism is demonstrated. The compatibility of recent next-to-leading order strange quark distributions with the available dimuon and F2νN data is investigated. It is shown that final conclusions concerning these distributions afford further analyses of presently available and/or forthcoming neutrino data.

Mediating electrostatic binding of 1-butyl-3-methylimidazolium chloride to enzyme surfaces improves conformational stability.

PubMed

Nordwald, Erik M; Kaar, Joel L

2013-08-01

We have recently developed a general approach to improve the utility of enzymes in ionic liquids (ILs) via tuning of the ratio of enzyme-containing positive to negative surface charges. In this work, the impact of enzyme surface charge ratio on the biophysical interaction of 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) with chymotrypsin and lipase was investigated to understand this approach at the molecular level. Results of fluorescence quenching assays indicated that the extent of binding of the [BMIM] cation decreased (7- and 3.5-fold for chymotrypsin and lipase, respectively) as a function of increasing ratio of positive to negative surface charges. Conformational stability assays further showed a close correlation between thermodynamic stabilization and enzyme surface charge ratio as well as [BMIM] binding. As evidence of this correlation, succinylation and acetylation resulted in the stabilization of chymotrypsin in 10% (v/v) [BMIM][Cl] by 17.0 and 6.6 kJ/mol, respectively, while cationization destabilized chymotrypsin by 3.6 kJ/mol. Combined, these results indicate that altering the surface charge ratio mediates the organization of IL molecules, namely, [BMIM] and [Cl], around the enzymes. Preferential exclusion of [Cl], in particular, via lowering of the ratio of positive to negative surface charges, correlated with increased enzyme stability. Accordingly, these results more broadly provide insight into the mechanism of stabilization in ILs via charge modification.

A threshold effect for spacecraft charging

NASA Technical Reports Server (NTRS)

Olsen, R. C.

1983-01-01

The borderline case between no charging and large (kV) negative potentials for eclipse charging events on geosynchronous satellites is investigated, and the dependence of this transition on a threshold energy in the ambient plasma is examined. Data from the Applied Technology Satellite 6 and P78-2 (SCATHA) show that plasma sheet fluxes must extend above 10 keV for these satellites to charge in eclipse. The threshold effect is a result of the shape of the normal secondary yield curve, in particular the high energy crossover, where the secondary yield drops below 1. It is found that a large portion of the ambient electron flux must exceed this energy for a negative current to exist.

Negative Differential Conductance in Polyporphyrin Oligomers with Nonlinear Backbones.

PubMed

Kuang, Guowen; Chen, Shi Zhang; Yan, Linghao; Chen, Ke Qiu; Shang, Xuesong; Liu, Pei Nian; Lin, Nian

2018-01-17

We study negative differential conductance (NDC) effects in polyporphyrin oligomers with nonlinear backbones. Using a low-temperature scanning tunneling microscope, we selectively controlled the charge transport path in single oligomer wires. We observed robust NDC when charge passed through a T-shape junction, bistable NDC when charge passed through a 90° kink and no NDC when charge passed through a 120° kink. Aided by density functional theory with nonequilibrium Green's functions simulations, we attributed this backbone-dependent NDC to bias-modulated hybridization of the electrode states with the resonant transport molecular orbital. We argue this mechanism is generic in molecular systems, which opens a new route of designing molecular NDC devices.

Space charge effects on the third order coupled resonance

NASA Astrophysics Data System (ADS)

Franchetti, Giuliano; Gilardoni, Simone; Huschauer, Alexander; Schmidt, Frank; Wasef, Raymond

2017-08-01

The effect of space charge on bunched beams has been the subject of numerous numerical and experimental studies in the first decade of 2000. Experimental campaigns performed at the CERN Proton Synchrotron in 2002 and at the GSI SIS18 in 2008 confirmed the existence of an underlying mechanism in the beam dynamics of periodic resonance crossing induced by the synchrotron motion and space charge. In this article we present an extension of the previous studies to describe the effect of space charge on a controlled coupled (2D) third order resonance. The experimental and simulation results of this latest campaign shed a new light on the difficulties of the 2D particle dynamics. We find striking experimental evidence that space charge and the coupled resonance create an unusual coupling in the phase space, leading to the formation of an asymmetric halo. Moreover, this study demonstrates a clear link between halo formation and fixed-lines.

Self-consistent simulation of radio frequency multipactor on micro-grooved dielectric surface

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

Cai, Libing; Wang, Jianguo, E-mail: wanguiuc@mail.xjtu.edu.cn; Northwest Institute of Nuclear Technology, Xi'an, Shaanxi 710024

2015-02-07

The multipactor plays a key role in the surface breakdown on the feed dielectric window irradiated by high power microwave. To study the suppression of multipactor, a 2D electrostatic PIC-MCC simulation code was developed. The space charge field, including surface deposited charge and multipactor electron charge field, is obtained by solving 2D Poisson's equation in time. Therefore, the simulation is self-consistent and does not require presetting a fixed space charge field. By using this code, the self-consistent simulation of the RF multipactor on the periodic micro-grooved dielectric surface is realized. The 2D space distributions of the multipactor electrons and spacemore » charge field are presented. From the simulation results, it can be found that only half slopes have multipactor discharge when the slope angle exceeds a certain value, and the groove presents a pronounced suppression effect on the multipactor.« less

Study Trapped Charge Distribution in P-Channel Silicon-Oxide-Nitride-Oxide-Silicon Memory Device Using Dynamic Programming Scheme

NASA Astrophysics Data System (ADS)

Li, Fu-Hai; Chiu, Yung-Yueh; Lee, Yen-Hui; Chang, Ru-Wei; Yang, Bo-Jun; Sun, Wein-Town; Lee, Eric; Kuo, Chao-Wei; Shirota, Riichiro

2013-04-01

In this study, we precisely investigate the charge distribution in SiN layer by dynamic programming of channel hot hole induced hot electron injection (CHHIHE) in p-channel silicon-oxide-nitride-oxide-silicon (SONOS) memory device. In the dynamic programming scheme, gate voltage is increased as a staircase with fixed step amplitude, which can prohibits the injection of holes in SiN layer. Three-dimensional device simulation is calibrated and is compared with the measured programming characteristics. It is found, for the first time, that the hot electron injection point quickly traverses from drain to source side synchronizing to the expansion of charged area in SiN layer. As a result, the injected charges quickly spread over on the almost whole channel area uniformly during a short programming period, which will afford large tolerance against lateral trapped charge diffusion by baking.

Implementation of a Battery Health Monitor and Vertical Lift Aircraft Testbed for the Application of an Electrochemisty-Based State of Charge Estimator

NASA Technical Reports Server (NTRS)

Potteiger, Timothy R.; Eure, Kenneth W.; Levenstein, David

2017-01-01

Prediction methods concerning remaining charge in lithium-ion batteries that power unmanned aerial vehicles are of critical concern for the safe fulfillment of mission objectives. In recent years, lithium-ion batteries have been the power source for both fixed wing and vertical lift electric vehicles. The purpose of this document is to describe in detail the implementation of a battery health monitor for estimating the state of charge of a lithium-ion battery and a lithium-ion polymer battery that is used to power a vertical lift aircraft test-bed. It will be demonstrated that an electro-chemistry based state of charge estimator effectively tracks battery discharge characteristics and may be employed as a useful tool in monitoring battery health.

Stability of nTiO2 particles and their attachment to sand: Effects of humic acid at different pH.

PubMed

Wu, Yang; Cheng, Tao

2016-01-15

The fate and transport of nano-scale or micro-scale titanium dioxide particles (nTiO2) in subsurface environments are strongly influenced by the stability of nTiO2 and their attachment to sediment grains. nTiO2 may carry either positive or negative charges in natural water, therefore, environmental factors such as pH, humic substances, and Fe oxyhydroxide coatings on sediment grains, which are known to control the stability and transport of negatively-charged colloids, may influence nTiO2 in different manners. The objective of this study is to investigate the effects of pH and humic acid (HA) on the stability and attachment of nTiO2 to sand at HA concentrations that are relevant to typical groundwater conditions, so that mechanisms that control nTiO2 immobilization and transport in natural systems can be elucidated. Stability and attachment of nTiO2 to quartz sand and Fe oxyhydroxide coated quartz sand are experimentally measured under a range of HA concentrations at pH5 and 9. Results show that at pH5, negatively-charged HA strongly adsorbs to positively-charged nTiO2 and Fe oxyhydroxide, which, at low HA concentrations, partially neutralizes the positive charges on nTiO2 and Fe oxyhydroxide, and therefore decreases the repulsive electrostatic forces between the surfaces, resulting in nTiO2 aggregation and attachment. At high HA concentrations, adsorbed HA reverses the surface charges of nTiO2 and Fe oxyhydroxide, and makes nTiO2 and Fe oxyhydroxide strongly negatively charged, resulting in stable nTiO2 suspension and low nTiO2 attachment. At pH9, HA, nTiO2, and Fe oxyhydroxide are all negatively charged, and HA adsorption is low and does not have a strong impact on the stability and attachment of nTiO2. Overall, this study shows that changes in surface charges of nTiO2 and Fe oxyhydroxide coating caused by HA adsorption is a key factor that influences the stability and attachment of nTiO2. Copyright © 2015 Elsevier B.V. All rights reserved.

Charge-dependent flow and the search for the chiral magnetic wave in Pb-Pb collisions at s N N = 2.76 TeV

DOE PAGES

Adam, J.; Adamová, D.; Aggarwal, M. M.; ...

2016-04-08

We report on measurements of a charge-dependent flow using a novel three-particle correlator with ALICE in Pb-Pb collisions at the CERN Large Hadron Collider (LHC), and discuss the implications for observation of local parity violation and the chiral magnetic wave (CMW) in heavy-ion collisions. Charge-dependent flow is reported for different collision centralities as a function of the event charge asymmetry. While our results are in qualitative agreement with expectations based on the CMW, the nonzero signal observed in higher harmonics correlations indicates a possible significant background contribution. We also present results on a differential correlator, where the flow of positivemore » and negative charges is reported as a function of the mean charge of the particles and their pseudorapidity separation. We argue that this differential correlator is better suited to distinguish the differences in positive and negative charges expected due to the CMW and the background effects, such as local charge conservation coupled with strong radial and anisotropic flow.« less

Charge-dependent flow and the search for the chiral magnetic wave in Pb-Pb collisions at √{sN N}=2.76 TeV

NASA Astrophysics Data System (ADS)

Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Almaraz, J. R. M.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Balasubramanian, S.; Baldisseri, A.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Benacek, P.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biro, G.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Bourjau, C.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Ceballos Sanchez, C.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chauvin, A.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Cho, S.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; de, S.; de Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; de Falco, A.; de Gruttola, D.; De Marco, N.; de Pasquale, S.; Deisting, A.; Deloff, A.; Dénes, E.; Deplano, C.; Dhankher, P.; di Bari, D.; di Mauro, A.; di Nezza, P.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Endress, E.; Engel, H.; Epple, E.; Erazmus, B.; Erdemir, I.; Erhardt, F.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fronze, G. G.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Grachov, O. A.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gronefeld, J. M.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hamon, J. C.; Harris, J. W.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hillemanns, H.; Hippolyte, B.; Horak, D.; Hosokawa, R.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Inaba, M.; Incani, E.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacazio, N.; Jacobs, P. M.; Jadhav, M. B.; Jadlovska, S.; Jadlovsky, J.; Jahnke, C.; Jakubowska, M. J.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Mohisin Khan, M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, D. W.; Kim, D. J.; Kim, D.; Kim, H.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Klewin, S.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Králik, I.; Kravčáková, A.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kumar, S.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Ladron de Guevara, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Lee, S.; Lehas, F.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; León Vargas, H.; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Lutz, T. H.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martin Blanco, J.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; McDonald, D.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Moreira de Godoy, D. A.; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Munzer, R. H.; Murakami, H.; Murray, S.; Musa, L.; Musinsky, J.; Naik, B.; Nair, R.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Natal da Luz, H.; Nattrass, C.; Navarro, S. R.; Nayak, K.; Nayak, R.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pal, S. K.; Pan, J.; Pandey, A. K.; Papcun, P.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Pei, H.; Peitzmann, T.; Pereira da Costa, H.; Peresunko, D.; Pérez Lara, C. E.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pimentel, L. O. D. L.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Rami, F.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Read, K. F.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Šándor, L.; Sandoval, A.; Sano, M.; Sarkar, D.; Sarma, P.; Scapparone, E.; Scarlassara, F.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Šefčík, M.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Senyukov, S.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; de Souza, R. D.; Sozzi, F.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Stachel, J.; Stan, I.; Stankus, P.; Stefanek, G.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Suljic, M.; Sultanov, R.; Šumbera, M.; Szabo, A.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tangaro, M. A.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trombetta, G.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; van der Maarel, J.; van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Villatoro Tello, A.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Weiser, D. F.; Wessels, J. P.; Westerhoff, U.; Whitehead, A. M.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yang, H.; Yang, P.; Yano, S.; Yasar, C.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yoon, J. H.; Yurchenko, V.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhang, C.; Zhang, Z.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.; Alice Collaboration

2016-04-01

We report on measurements of a charge-dependent flow using a novel three-particle correlator with ALICE in Pb-Pb collisions at the CERN Large Hadron Collider (LHC), and discuss the implications for observation of local parity violation and the chiral magnetic wave (CMW) in heavy-ion collisions. Charge-dependent flow is reported for different collision centralities as a function of the event charge asymmetry. While our results are in qualitative agreement with expectations based on the CMW, the nonzero signal observed in higher harmonics correlations indicates a possible significant background contribution. We also present results on a differential correlator, where the flow of positive and negative charges is reported as a function of the mean charge of the particles and their pseudorapidity separation. We argue that this differential correlator is better suited to distinguish the differences in positive and negative charges expected due to the CMW and the background effects, such as local charge conservation coupled with strong radial and anisotropic flow.

Ionization Efficiency of Doubly Charged Ions Formed from Polyprotic Acids in Electrospray Negative Mode

NASA Astrophysics Data System (ADS)

Liigand, Piia; Kaupmees, Karl; Kruve, Anneli

2016-07-01

The ability of polyprotic acids to give doubly charged ions in negative mode electrospray was studied and related to physicochemical properties of the acids via linear discriminant analysis (LDA). It was discovered that the compound has to be strongly acidic (low p K a1 and p K a2) and to have high hydrophobicity (log P ow) to become multiply charged. Ability to give multiply charged ions in ESI/MS cannot be directly predicted from the solution phase acidities. Therefore, for the first time, a quantitative model to predict the charge state of the analyte in ESI/MS is proposed and validated for small anions. Also, a model to predict ionization efficiencies of these analytes was developed. Results indicate that acidity of the analyte, its octanol-water partition coefficient, and charge delocalization are important factors that influence ionization efficiencies as well as charge states of the analytes. The pH of the solvent was also found to be an important factor influencing the ionization efficiency of doubly charged ions.

25 CFR 41.3 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... AFFAIRS, DEPARTMENT OF THE INTERIOR EDUCATION GRANTS TO TRIBALLY CONTROLLED COMMUNITY COLLEGES AND NAVAJO..., nation, pueblo, rancheria, or other organized group or community, including any Alaskan Native Village or... plant, fixed charges, and other related expenses, but not including expenditures for the acquisition or...

78 FR 71702 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Notice of Filing of Proposed...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-29

... unexpected haircut or capital charge that does not fundamentally change its risk profile), and (ii) return all or a portion of the collateral premium amount if it believes that the member's risk profile does...

Influence of intra-molecular flexibility on the elastic property of double-stranded DNA film on a substrate

NASA Astrophysics Data System (ADS)

Wu, Jun-Zheng; Meng, Wei-Lie; Tang, Heng-Song; Zhang, Neng-Hui

2017-05-01

DNA film self-assembled or nanografted on a substrate, as a kind of soft matter, consists of fixed DNA chains endowed with negative charges and an aqueous solution full of cations, anions and water molecules. Their thermal/electrical/mechanical properties are closely related to the complex biodetection signals in nano-/micro-scale biosensors and other new genome technologies. This makes it important to properly characterize these properties. In this paper, the effect of flexible micro-scale configurations on the elastic moduli of DNA films is investigated. First, illuminated by Qiu’s sphere model, an alternative bead-chain model in terms of the Yukawa potential is presented for flexible intra-DNA configurations to describe interactions between DNA fragments. The effective charges of coarse-grained DNA beads could be derived, in which the empirical parameters are identified by curve fitting with Qiu’s experimental data. Second, the updated mesoscopic bead-chain model and the thought experiment of a continuum compression bar are used to compare the elastic moduli of double-stranded DNA (dsDNA) films prepared by self-assembling and nanografting techniques. Configurational sampling is achieved via Monte Carlo simulation. Our predictions quantitatively or qualitatively agree well with the relevant experiments on the effective charge of dsDNA from low to moderate monovalent counterion concentration, immobilization deflection of single-stranded DNA (ssDNA) or dsDNA microcantilever with the variation of salt concentration, and elastic modulus of ssDNA film in the air. The results reveal that different solution environment stimulates the diverse mechanical properties of dsDNA film on a substrate, and the end effect (i.e. terminal group effect) makes self-assembling dsDNA film stiffer in the sense of the same average packing density.

The effect of light soaking on crystalline silicon surface passivation by atomic layer deposited Al2O3

NASA Astrophysics Data System (ADS)

Liao, Baochen; Stangl, Rolf; Mueller, Thomas; Lin, Fen; Bhatia, Charanjit S.; Hoex, Bram

2013-01-01

The effect of light soaking of crystalline silicon wafer lifetime samples surface passivated by thermal atomic layer deposited (ALD) Al2O3 is investigated in this paper. Contrary to other passivation materials used in solar cell applications (i.e., SiO2, SiNx), using thermal ALD Al2O3, an increase in effective carrier lifetime after light soaking under standard testing conditions is observed for both p-type (˜45%) and n-type (˜60%) FZ c-Si lifetime samples. After light soaking and storing the samples in a dark and dry environment, the effective lifetime decreases again and practically returns to the value before light soaking. The rate of lifetime decrease after light soaking is significantly slower than the rate of lifetime increase by light soaking. To investigate the underlying mechanism, corona charge experiments are carried out on p-type c-Si samples before and after light soaking. The results indicate that the negative fixed charge density Qf present in the Al2O3 films increases due to the light soaking, which results in an improved field-effect passivation. Numerical calculations also confirm that the improved field-effect passivation is the main contributor for the increased effective lifetime after light soaking. To further understand the light soaking phenomenon, a kinetic model—a charge trapping/de-trapping model—is proposed to explain the time dependent behavior of the lifetime increase/decrease observed under/after light soaking. The trap model fits the experimental results very well. The observed light enhanced passivation for ALD Al2O3 passivated c-Si is of technological relevance, because solar cell devices operate under illumination, thus an increase in solar cell efficiency due to light soaking can be expected.

Whole body acid-base modeling revisited.

PubMed

Ring, Troels; Nielsen, Søren

2017-04-01

The textbook account of whole body acid-base balance in terms of endogenous acid production, renal net acid excretion, and gastrointestinal alkali absorption, which is the only comprehensive model around, has never been applied in clinical practice or been formally validated. To improve understanding of acid-base modeling, we managed to write up this conventional model as an expression solely on urine chemistry. Renal net acid excretion and endogenous acid production were already formulated in terms of urine chemistry, and we could from the literature also see gastrointestinal alkali absorption in terms of urine excretions. With a few assumptions it was possible to see that this expression of net acid balance was arithmetically identical to minus urine charge, whereby under the development of acidosis, urine was predicted to acquire a net negative charge. The literature already mentions unexplained negative urine charges so we scrutinized a series of seminal papers and confirmed empirically the theoretical prediction that observed urine charge did acquire negative charge as acidosis developed. Hence, we can conclude that the conventional model is problematic since it predicts what is physiologically impossible. Therefore, we need a new model for whole body acid-base balance, which does not have impossible implications. Furthermore, new experimental studies are needed to account for charge imbalance in urine under development of acidosis. Copyright © 2017 the American Physiological Society.

Modeling the total dust production of Enceladus from stochastic charge equilibrium and simulations

NASA Astrophysics Data System (ADS)

Meier, Patrick; Motschmann, Uwe; Schmidt, Jürgen; Spahn, Frank; Hill, Thomas W.; Dong, Yaxue; Jones, Geraint H.; Kriegel, Hendrik

2015-12-01

Negatively and positively charged nano-sized ice grains were detected in the Enceladus plume by the Cassini Plasma Spectrometer (CAPS). However, no data for uncharged grains, and thus for the total amount of dust, are available. In this paper we estimate this population of uncharged grains based on a model of stochastic charging in thermodynamic equilibrium and on the assumption of quasi-neutrality in the plasma-dust system. This estimation is improved upon by combining simulations of the dust component of the plume and simulations for the plasma environment into one self-consistent model. Calibration of this model with CAPS data provides a total dust production rate of about 12 kg s-1, including larger dust grains up to a few microns in size. We find that the fraction of charged grains dominates over that of the uncharged grains. Moreover, our model reproduces densities of both negatively and positively charged nanograins measured by Cassini CAPS. In Enceladus' plume ion densities up to ~104cm-3 are required by the self-consistent model, resulting in an electron depletion of about 50% in the plasma, because electrons are attached to the negatively charged nanograins. These ion densities correspond to effective ionization rates of about 10-7s-1, which are about two orders of magnitude higher than expected.

Electrolyte effects in a model of proton discharge on charged electrodes

NASA Astrophysics Data System (ADS)

Wiebe, Johannes; Kravchenko, Kateryna; Spohr, Eckhard

2015-01-01

We report results on the influence of NaCl electrolyte dissolved in water on proton discharge reactions from aqueous solution to charged platinum electrodes. We have extended a recently developed combined proton transfer/proton discharge model on the basis of empirical valence bond theory to include NaCl solutions with several different concentrations of cations and anions, both stoichiometric (1:1) compositions and non-stoichiometric ones with an excess of cations. The latter solutions partially screen the electrostatic potential from the surface charge of the negatively charged electrode. 500-1000 trajectories of a discharging proton were integrated by molecular dynamics simulations until discharge occurred, or for at most 1.5 ns. The results show a strong dependence on ionic strength, but only a weak dependence on the screening behavior, when comparing stoichiometric and non-stoichiometric solutions. Overall, the Na+ cations exert a more dominant effect on the discharge reaction, which we argue is likely due to the very rigid arrangements of the cations on the negatively polarized electrode surface. Thus, our model predicts, for the given and very high negative surface charge densities, the fastest discharge reaction for pure water, but obviously cannot take into account the fact that such high charge densities are even more out of reach experimentally than for higher electrolyte concentrations.

Role of electrostatic interactions in the toxicity of titanium dioxide nanoparticles toward Escherichia coli.

PubMed

Pagnout, Christophe; Jomini, Stéphane; Dadhwal, Mandeep; Caillet, Céline; Thomas, Fabien; Bauda, Pascale

2012-04-01

The increasing production and use of titanium dioxide nanoparticles (NP-TiO(2)) has led to concerns about their possible impact on the environment. Bacteria play crucial roles in ecosystem processes and may be subject to the toxicity of these nanoparticles. In this study, we showed that at low ionic strength, the cell viability of Escherichia coli was more severely affected at pH 5.5 than at pH 7.0 and pH 9.5. At pH 5.5, nanoparticles (positively charged) strongly interacted with the bacterial cells (negatively charged) and accumulated on their surfaces. This phenomenon was observed in a much lower degree at pH 7.0 (NP-TiO(2) neutrally charged and cells negatively charged) and pH 9.5 (both NP-TiO(2) and cells negatively charged). It was also shown that the addition of electrolytes (NaCl, CaCl(2), Na(2)SO(4)) resulted in a gradual reduction of the NP-TiO(2) toxicity at pH 5.5 and an increase in this toxicity at pH 9.5, which was closely related to the reduction of the NP-TiO(2) and bacterial cell electrostatic charges. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

Membrane Permeabilization Induced by Sphingosine: Effect of Negatively Charged Lipids

PubMed Central

Jiménez-Rojo, Noemi; Sot, Jesús; Viguera, Ana R.; Collado, M. Isabel; Torrecillas, Alejandro; Gómez-Fernández, J.C.; Goñi, Félix M.; Alonso, Alicia

2014-01-01

Sphingosine [(2S, 3R, 4E)-2-amino-4-octadecen-1, 3-diol] is the most common sphingoid long chain base in sphingolipids. It is the precursor of important cell signaling molecules, such as ceramides. In the last decade it has been shown to act itself as a potent metabolic signaling molecule, by activating a number of protein kinases. Moreover, sphingosine has been found to permeabilize phospholipid bilayers, giving rise to vesicle leakage. The present contribution intends to analyze the mechanism by which this bioactive lipid induces vesicle contents release, and the effect of negatively charged bilayers in the release process. Fluorescence lifetime measurements and confocal fluorescence microscopy have been applied to observe the mechanism of sphingosine efflux from large and giant unilamellar vesicles; a graded-release efflux has been detected. Additionally, stopped-flow measurements have shown that the rate of vesicle permeabilization increases with sphingosine concentration. Because at the physiological pH sphingosine has a net positive charge, its interaction with negatively charged phospholipids (e.g., bilayers containing phosphatidic acid together with sphingomyelins, phosphatidylethanolamine, and cholesterol) gives rise to a release of vesicular contents, faster than with electrically neutral bilayers. Furthermore, phosphorous 31-NMR and x-ray data show the capacity of sphingosine to facilitate the formation of nonbilayer (cubic phase) intermediates in negatively charged membranes. The data might explain the pathogenesis of Niemann-Pick type C1 disease. PMID:24940775

Bounding Extreme Spacecraft Charging in the Lunar Environment

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Parker, Linda N.

2008-01-01

Robotic and manned spacecraft from the Apollo era demonstrated that the lunar surface in daylight will charge to positive potentials of a few tens of volts because the photoelectron current dominates the charging process. In contrast, potentials of the lunar surface in darkness which were predicted to be on the order of a hundred volts negative in the Apollo era have been shown more recently to reach values of a few hundred volts negative with extremes on the order of a few kilovolts. The recent measurements of night time lunar surface potentials are based on electron beams in the Lunar Prospector Electron Reflectometer data sets interpreted as evidence for secondary electrons generated on the lunar surface accelerated through a plasma sheath from a negatively charged lunar surface. The spacecraft potential was not evaluated in these observations and therefore represents a lower limit to the magnitude of the lunar negative surface potential. This paper will describe a method for obtaining bounds on the magnitude of lunar surface potentials from spacecraft measurements in low lunar orbit based on estimates of the spacecraft potential. We first use Nascap-2k surface charging analyses to evaluate potentials of spacecraft in low lunar orbit and then include the potential drops between the ambient space environment and the spacecraft to the potential drop between the lunar surface and the ambient space environment to estimate the lunar surface potential from the satellite measurements.

Concentration polarization-based nonlinear electrokinetics in porous media: induced-charge electroosmosis.

PubMed

Leinweber, Felix C; Tallarek, Ulrich

2005-11-24

We have investigated induced-charge electroosmotic flow in a fixed bed of ion-permselective glass beads by quantitative confocal laser scanning microscopy. Externally applied electrical fields induce concentration polarization (CP) in the porous medium due to coupled mass and charge transport normal to the charge-selective interfaces. These data reveal the generation of a nonequilibrium electrical double layer in the depleted CP zones and the adjoining anodic hemispheres of the (cation-selective) glass beads above a critical field strength. This initiates CP-based induced-charge electroosmosis along curved interfaces of the quasi-electroneutral macropore space between glass beads. Caused by mutual interference of resulting nonlinear flow with (flow-inducing) space charge regions, an electrohydrodynamic instability can appear locally and realize turbulent flow behavior at low Reynolds numbers. It is characterized by a local destruction of the CP zones and concomitant removal of diffusion-limited mass transfer. More efficient pore-scale lateral mixing also improves macroscopic transport, which is reflected in the significantly reduced axial dispersion of a passive tracer.

A new charge-tagged proline-based organocatalyst for mechanistic studies using electrospray mass spectrometry

PubMed Central

Willms, J Alexander; Beel, Rita; Schmidt, Martin L; Mundt, Christian

2014-01-01

Summary A new 4-hydroxy-L-proline derivative with a charged 1-ethylpyridinium-4-phenoxy substituent has been synthesized with the aim of facilitating mechanistic studies of proline-catalyzed reactions by ESI mass spectrometry. The charged residue ensures a strongly enhanced ESI response compared to neutral unmodified proline. The connection by a rigid linker fixes the position of the charge tag far away from the catalytic center in order to avoid unwanted interactions. The use of a charged catalyst leads to significantly enhanced ESI signal abundances for every catalyst-derived species which are the ones of highest interest present in a reacting solution. The new charged proline catalyst has been tested in the direct asymmetric inverse aldol reaction between aldehydes and diethyl ketomalonate. Two intermediates in accordance with the List–Houk mechanism for enamine catalysis have been detected and characterized by gas-phase fragmentation. In addition, their temporal evolution has been followed using a microreactor continuous-flow technique. PMID:25246962

Surface charge effects in protein adsorption on nanodiamonds

NASA Astrophysics Data System (ADS)

Aramesh, M.; Shimoni, O.; Ostrikov, K.; Prawer, S.; Cervenka, J.

2015-03-01

Understanding the interaction of proteins with charged diamond nanoparticles is of fundamental importance for diverse biomedical applications. Here we present a thorough study of protein binding, adsorption kinetics and structure on strongly positively (hydrogen-terminated) and negatively (oxygen-terminated) charged nanodiamond particles using a quartz crystal microbalance by dissipation and infrared spectroscopy. By using two model proteins (bovine serum albumin and lysozyme) of different properties (charge, molecular weight and rigidity), the main driving mechanism responsible for the protein binding to the charged nanoparticles was identified. Electrostatic interactions were found to dominate the protein adsorption dynamics, attachment and conformation. We developed a simple electrostatic model that can qualitatively explain the observed adsorption behaviour based on charge-induced pH modifications near the charged nanoparticle surfaces. Under neutral conditions, the local pH around the positively and negatively charged nanodiamonds becomes very high (11-12) and low (1-3) respectively, which has a profound impact on the protein charge, hydration and affinity to the nanodiamonds. Small proteins (lysozyme) were found to form multilayers with significant conformational changes to screen the surface charge, while larger proteins (albumin) formed monolayers with minor conformational changes. The findings of this study provide a step forward toward understanding and eventually predicting nanoparticle interactions with biofluids.Understanding the interaction of proteins with charged diamond nanoparticles is of fundamental importance for diverse biomedical applications. Here we present a thorough study of protein binding, adsorption kinetics and structure on strongly positively (hydrogen-terminated) and negatively (oxygen-terminated) charged nanodiamond particles using a quartz crystal microbalance by dissipation and infrared spectroscopy. By using two model proteins (bovine serum albumin and lysozyme) of different properties (charge, molecular weight and rigidity), the main driving mechanism responsible for the protein binding to the charged nanoparticles was identified. Electrostatic interactions were found to dominate the protein adsorption dynamics, attachment and conformation. We developed a simple electrostatic model that can qualitatively explain the observed adsorption behaviour based on charge-induced pH modifications near the charged nanoparticle surfaces. Under neutral conditions, the local pH around the positively and negatively charged nanodiamonds becomes very high (11-12) and low (1-3) respectively, which has a profound impact on the protein charge, hydration and affinity to the nanodiamonds. Small proteins (lysozyme) were found to form multilayers with significant conformational changes to screen the surface charge, while larger proteins (albumin) formed monolayers with minor conformational changes. The findings of this study provide a step forward toward understanding and eventually predicting nanoparticle interactions with biofluids. Electronic supplementary information (ESI) available: The FTIR spectrum of nanodiamonds, QCM-D profiles of 50 nm nanodiamond adsorption on silica surfaces, QCM-D profiles of protein desorption after rinsing with water (rinsing experiment) and the full FTIR spectrum of proteins before and after adsorption on ND particles. See DOI: 10.1039/c5nr00250h

Charge Induced Dynamics of Water in a Graphene–Mica Slit Pore

PubMed Central

2017-01-01

We use atomic force microscopy to in situ investigate the dynamic behavior of confined water at the interface between graphene and mica. The graphene is either uncharged, negatively charged, or positively charged. At high humidity, a third water layer will intercalate between graphene and mica. When graphene is negatively charged, the interface fills faster with a complete three layer water film, compared to uncharged graphene. As charged positively, the third water layer dewets the interface, either by evaporation into the ambient or by the formation of three-dimensional droplets under the graphene, on top of the bilayer. Our experimental findings reveal novel phenomena of water at the nanoscale, which are interesting from a fundamental point of view and demonstrate the direct control over the wetting properties of the graphene/water interface. PMID:28985466

Negative Charge Neutralization in the Loops and Turns of Outer Membrane Phospholipase A Impacts Folding Hysteresis at Neutral pH.

PubMed

McDonald, Sarah K; Fleming, Karen G

2016-11-08

Hysteresis in equilibrium protein folding titrations is an experimental barrier that must be overcome to extract meaningful thermodynamic quantities. Traditional approaches to solving this problem involve testing a spectrum of solution conditions to find ones that achieve path independence. Through this procedure, a specific pH of 3.8 was required to achieve path independence for the water-to-bilayer equilibrium folding of outer membrane protein OmpLA. We hypothesized that the neutralization of negatively charged side chains (Asp and Glu) at pH 3.8 could be the physical basis for path-independent folding at this pH. To test this idea, we engineered variants of OmpLA with Asp → Asn and Glu → Gln mutations to neutralize the negative charges within various regions of the protein and tested for reversible folding at neutral pH. Although not fully resolved, our results show that these mutations in the periplasmic turns and extracellular loops are responsible for 60% of the hysteresis in wild-type folding. Overall, our study suggests that negative charges impact the folding hysteresis in outer membrane proteins and their neutralization may aid in protein engineering applications.

Positive and negative contribution to birefringence in a family of carbonates: A Born effective charges analysis

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

Jing, Qun; Yang, Guang; Hou, Juan

It is an important topic to investigate the birefringence and reveal the contribution from ions to birefringence because it plays an important role in nonlinear optical materials. In this paper, the birefringence of carbonates with coplanar CO{sub 3} groups were investigated using the first-principles method. The results show that the lead carbonates exhibit relative large birefringence. After detailed investigate the electronic structures, and Born effective charges, the authors find out that anisotropic electron distribution in the CO{sub 3} groups and Pb atoms give positive contribution, while the negative contribution was found from fluorine atoms, meanwhile the Ca, Mg, and Cdmore » atoms give very small contribution to birefringence. - Graphical abstract: Using the DFT and Born effective charges, the birefringence and the contribution of ions were investigated, the positive and negative contribution was found from Pb and F ions, respectively. - Highlights: • Optical properties and Born effective charges of carbonates are investigated. • Lead carbonates exhibit relative large birefringence. • Coplanar CO{sub 3} groups and Pb atoms give positive contribution. • F atoms give negative contribution. • Ca, Mg, and Cd atoms give very small contribution.« less

31 CFR 359.12 - What happens in deflationary conditions?

Code of Federal Regulations, 2010 CFR

2010-07-01

... deflationary situations, the semiannual inflation rate may be negative. Negative semiannual inflation rates will be used in the same way as positive semiannual inflation rates. However, if the semiannual inflation rate is negative to the extent that it completely offsets the fixed rate of return, the redemption...

The influence of ligand charge and length on the assembly of Brome mosaic virus derived virus-like particles with magnetic core

NASA Astrophysics Data System (ADS)

Mieloch, Adam A.; Krecisz, Monika; Rybka, Jakub D.; Strugała, Aleksander; Krupiński, Michał; Urbanowicz, Anna; Kozak, Maciej; Skalski, Bohdan; Figlerowicz, Marek; Giersig, Michael

2018-03-01

Virus-like particles (VLPs) have sparked a great interest in the field of nanobiotechnology and nanomedicine. The introduction of superparamagnetic nanoparticles (SPIONs) as a core, provides potential use of VLPs in the hyperthermia therapy, MRI contrast agents and magnetically-powered delivery agents. Magnetite NPs also provide a significant improvement in terms of VLPs stability. Moreover employing viral structural proteins as self-assembling units has opened a new paths for targeted therapy, drug delivery systems, vaccines design, and many more. In many cases, the self-assembly of a virus strongly depends on electrostatic interactions between positively charged groups of the capsid proteins and negatively charged nucleic acid. This phenomenon imposes the negative net charge as a key requirement for the core nanoparticle. In our experiments, Brome mosaic virus (BMV) capsid proteins isolated from infected plants Hordeum vulgare were used. Superparamagnetic iron oxide nanoparticles (Fe3O4) with 15 nm in diameter were synthesized by thermal decomposition and functionalized with COOH-PEG-PL polymer or dihexadecylphosphate (DHP) in order to provide water solubility and negative charge required for the assembly. Nanoparticles were characterized by Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), Zeta Potential, Fourier Transformed Infrared Spectroscopy (FTIR) and Superconducting Quantum Interference Device (SQUID) magnetometry. TEM and DLS study were conducted to verify VLPs creation. This study demonstrates that the increase of negative surface charge is not a sufficient factor determining successful assembly. Additional steric interactions provided by longer ligands are crucial for the assembly of BMV SPION VLPs and may enhance the colloidal stability.

The influence of PAMAM dendrimers surface groups on their interaction with porcine pepsin.

PubMed

Ciolkowski, Michal; Rozanek, Monika; Bryszewska, Maria; Klajnert, Barbara

2013-10-01

In this study the ability of three polyamidoamine (PAMAM) dendrimers with different surface charge (positive, neutral and negative) to interact with a negatively charged protein (porcine pepsin) was examined. It was shown that the dendrimer with a positively charged surface (G4 PAMAM-NH2), as well as the dendrimer with a neutral surface (G4 PAMAM-OH), were able to inhibit enzymatic activity of pepsin. It was also found that these dendrimers act as mixed partially non-competitive pepsin inhibitors. The negatively charged dendrimer (G3.5 PAMAM-COOH) was not able to inhibit the enzymatic activity of pepsin, probably due to the electrostatic repulsion between this dendrimer and the protein. No correlation between changes in enzymatic activity of pepsin and alterations in CD spectrum of the protein was observed. It indicates that the interactions between dendrimers and porcine pepsin are complex, multidirectional and not dependent only on disturbances of the secondary structure. © 2013.

Comparative experimental study of gas evolution and gas consumption reactions in sealed Ni-Cd and Ni-MH cells

NASA Astrophysics Data System (ADS)

Cha, Chuansin; Yu, Jingxian; Zhang, Jixiao

The behavior of the sealed Ni-Cd and Ni-MH systems are compared experimentally with regard to their ability to consume gaseous products generated during the overcharge stage of these systems. It was found that the Ni-Cd system could only consume oxygen, while the Ni-MH system possesses the additional ability to adsorb hydrogen and to catalyze the recombination reaction of hydrogen and oxygen. The internal pressure within both sealed Ni-Cd cells and sealed Ni-MH cells can be kept well under control during the charge/overcharge processes if the rate of overcharge is not too high and if there is sufficient surplus of charging capacity at the negative electrodes. However, the internal pressure can rise to dangerously high levels if the rate of overcharge is too high or there is a deficiency of the charging capacity at the negative electrodes. The various factors that may affect the surplus of charging capacity of the negative electrodes are also discussed.

Quantum localization of classical mechanics

NASA Astrophysics Data System (ADS)

Batalin, Igor A.; Lavrov, Peter M.

2016-07-01

Quantum localization of classical mechanics within the BRST-BFV and BV (or field-antifield) quantization methods are studied. It is shown that a special choice of gauge fixing functions (or BRST-BFV charge) together with the unitary limit leads to Hamiltonian localization in the path integral of the BRST-BFV formalism. In turn, we find that a special choice of gauge fixing functions being proportional to extremals of an initial non-degenerate classical action together with a very special solution of the classical master equation result in Lagrangian localization in the partition function of the BV formalism.

Extension of the self-consistent-charge density-functional tight-binding method: third-order expansion of the density functional theory total energy and introduction of a modified effective coulomb interaction.

PubMed

Yang, Yang; Yu, Haibo; York, Darrin; Cui, Qiang; Elstner, Marcus

2007-10-25

The standard self-consistent-charge density-functional-tight-binding (SCC-DFTB) method (Phys. Rev. B 1998, 58, 7260) is derived by a second-order expansion of the density functional theory total energy expression, followed by an approximation of the charge density fluctuations by charge monopoles and an effective damped Coulomb interaction between the atomic net charges. The central assumptions behind this effective charge-charge interaction are the inverse relation of atomic size and chemical hardness and the use of a fixed chemical hardness parameter independent of the atomic charge state. While these approximations seem to be unproblematic for many covalently bound systems, they are quantitatively insufficient for hydrogen-bonding interactions and (anionic) molecules with localized net charges. Here, we present an extension of the SCC-DFTB method to incorporate third-order terms in the charge density fluctuations, leading to chemical hardness parameters that are dependent on the atomic charge state and a modification of the Coulomb scaling to improve the electrostatic treatment within the second-order terms. These modifications lead to a significant improvement in the description of hydrogen-bonding interactions and proton affinities of biologically relevant molecules.

78 FR 62352 - Proposed Agency Information Collection Activities; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-18

... or summary information concerning the costs incurred, and interchange transaction fees charged or... basis) aggregate or summary information concerning the costs incurred, and interchange transaction fees... costs and fixed costs, and to instruct respondents to exclude transactions monitoring from the...

Competition of density waves and quantum multicritical behavior in Dirac materials from functional renormalization

NASA Astrophysics Data System (ADS)

Classen, Laura; Herbut, Igor F.; Janssen, Lukas; Scherer, Michael M.

2016-03-01

We study the competition of spin- and charge-density waves and their quantum multicritical behavior for the semimetal-insulator transitions of low-dimensional Dirac fermions. Employing the effective Gross-Neveu-Yukawa theory with two order parameters as a model for graphene and a growing number of other two-dimensional Dirac materials allows us to describe the physics near the multicritical point at which the semimetallic and the spin- and charge-density-wave phases meet. With the help of a functional renormalization group approach, we are able to reveal a complex structure of fixed points, the stability properties of which decisively depend on the number of Dirac fermions Nf. We give estimates for the critical exponents and observe crucial quantitative corrections as compared to the previous first-order ɛ expansion. For small Nf, the universal behavior near the multicritical point is determined by the chiral Heisenberg universality class supplemented by a decoupled, purely bosonic, Ising sector. At large Nf, a novel fixed point with nontrivial couplings between all sectors becomes stable. At intermediate Nf, including the graphene case (Nf=2 ), no stable and physically admissible fixed point exists. Graphene's phase diagram in the vicinity of the intersection between the semimetal, antiferromagnetic, and staggered density phases should consequently be governed by a triple point exhibiting first-order transitions.

Video, LMA and ULF observations of a negative gigantic jet in North Texas

NASA Astrophysics Data System (ADS)

Bruning, E. C.; Cummer, S.; Palivec, K.; Lyons, W. A.; Chmielewski, V.; MacGorman, D. R.

2017-12-01

On 8 September 2016 at 0125:38 UTC video of a negative gigantic jet was captured from Hawley, TX. VHF Lightning Mapping Arrays in West Texas and Oklahoma also observed the parent flash (duration of about 1 s) and, for the first time, mapped dozens of points along ascending negative leaders, lasting about 50 ms, which extended well above cloud top to about 35 km MSL altitude. A few well-located VHF sources were also detected near 50 km. Together, the video and VHF observations provide additional confirmation of the altitude at which the leader-to-streamer transition takes place in gigantic jet discharges. ULF magnetic field data from the Duke iCMC network show a current excursion associated with the onset of the upward movement of negative charge and leaders in the VHF. As the gigantic jet reached its full height, current spiked to 80 kA, followed by several hundred milliseconds of continuing current of 10-20 kA. Total charge moment change was about 6000 C km. The storm complex produced predominantly negative large charge moment change events, which is characteristic of storms that produce negative gigantic jets.

[Sorption of microorganisms by fiber materials].

PubMed

Nikovskaia, G N; Gordienko, A S; Globa, L I

1986-01-01

Candida guilliermondii and Escherichia coli cells were adsorbed on glass and basalt fibres with a similar specific surface, but with a different charge. The quantity of adsorbed microorganisms did not depend on the type and charge of a fibre surface. However, cells were adsorbed faster and more firmly on positively charged and uncharged fibres than on negatively charged fibres.

Distributor means for charging particulate material into receptacles

DOEpatents

Greaves, Melvin J.

1977-06-14

Disclosed are receptacles, such as shaft furnaces illustrated by a blast furnace and an upright oil shale retort, embodying rotatable charge distributor means for distributing particulate charge material in the furnace, which charge distributor means can provide a high uniformity of distribution of various sizes of particles and also can provide and maintain a stock line of desired contour and heighth in the receptacle. The distributor means includes a hopper having rigidly fixed to it a plurality of downwardly extending chutes with lower discharge portions that discharge in concentric circular zones at the stock line. The distributor means includes a segmented portion at the juncture of the hopper and the chutes that divides the charge material discharged into the hopper in proportion to the area of the circular zone at the stock line that is fed by the chute. The distributor means embodies means for providing mass flow of the particulate charge material through the chutes to the stock line and for avoiding segregation between larger and smaller particles of charge material deposited at the stock line.

S1-S3 counter charges in the voltage sensor module of a mammalian sodium channel regulate fast inactivation.

PubMed

Groome, James R; Winston, Vern

2013-05-01

The movement of positively charged S4 segments through the electric field drives the voltage-dependent gating of ion channels. Studies of prokaryotic sodium channels provide a mechanistic view of activation facilitated by electrostatic interactions of negatively charged residues in S1 and S2 segments, with positive counterparts in the S4 segment. In mammalian sodium channels, S4 segments promote domain-specific functions that include activation and several forms of inactivation. We tested the idea that S1-S3 countercharges regulate eukaryotic sodium channel functions, including fast inactivation. Using structural data provided by bacterial channels, we constructed homology models of the S1-S4 voltage sensor module (VSM) for each domain of the mammalian skeletal muscle sodium channel hNaV1.4. These show that side chains of putative countercharges in hNaV1.4 are oriented toward the positive charge complement of S4. We used mutagenesis to define the roles of conserved residues in the extracellular negative charge cluster (ENC), hydrophobic charge region (HCR), and intracellular negative charge cluster (INC). Activation was inhibited with charge-reversing VSM mutations in domains I-III. Charge reversal of ENC residues in domains III (E1051R, D1069K) and IV (E1373K, N1389K) destabilized fast inactivation by decreasing its probability, slowing entry, and accelerating recovery. Several INC mutations increased inactivation from closed states and slowed recovery. Our results extend the functional characterization of VSM countercharges to fast inactivation, and support the premise that these residues play a critical role in domain-specific gating transitions for a mammalian sodium channel.

Molecular understanding of osmosis in semipermeable membranes.

PubMed

Raghunathan, A V; Aluru, N R

2006-07-14

We investigate single-file osmosis of water through a semipermeable membrane with an uncharged, a positively and a negatively charged nanopore. Molecular dynamics simulations indicate that the osmotic flux through a negatively charged pore (J_) is higher compared to the osmotic flux in a positively charged pore (J+) followed by the osmotic flux in the uncharged pore (J(0)), i.e., J_ > J+ > J(0). The molecular mechanisms governing osmosis, steady state osmosis, and the observed osmotic flux dependence on the nanopore charge are explained by computing all the molecular interactions involved and identifying the molecular interactions that play an important role during and after osmosis. This study helps in a fundamental understanding of osmosis and in the design of advanced nanoporous membranes for various applications of osmosis.

Controlling the electrophoretic mobility of single-walled carbon nanotubes: a comparison of theory and experiment.

PubMed

Usrey, Monica L; Nair, Nitish; Agnew, Daniel E; Pina, Cesar F; Strano, Michael S

2007-07-03

The electrophoretic mobilities of single-walled carbon nanotubes (SWNTs) in agarose gels subjected to negatively charged covalent functionalization and noncovalent anionic surfactant adsorption are compared using a simplified hydrodynamic model. Net charges are calculated on the basis of estimated friction coefficients for cylindrical rodlike particles. The effects of functionalization with negatively charged 4-hydroxybenzene diazonium and anionic sodium cholate are quantified and compared with model predictions. The adsorption of Na+ counterions into the nonionic surfactant layer adsorbed on SWNTs (Triton-X-405) is shown to induce a positive charge and reverse the mobility under select conditions. This effect has not been identified or quantified for nanoparticle systems and may be important in the processing of these systems.

The effects of vortex like distributed electron in magnetized multi-ion dusty plasmas

NASA Astrophysics Data System (ADS)

Haider, Md. Masum; Ferdous, Tahmina; Duha, Syed S.

2014-09-01

The nonlinear propagation of small but finite amplitude dust-ion-acoustic solitary waves in a magnetized, collisionless dusty plasma is investigated theoretically. It has been assumed that the electrons are trapped following the vortex-like distribution and that the negatively and positively charged ions are mobile with the presence of charge fluctuating stationary dusts, where ions mass provide the inertia and restoring forces are provided by the thermal pressure of hot electrons. A reductive perturbation method was employed to obtain a modified Korteweg-de Vries (mK-dV) equation for the first-order potential and a stationary solution is obtained. The effect of the presence of trapped electrons, negatively and positively charged ions and arbitrary charged dust grains are discussed.

The Role of Nanoparticle Surface Functionality in the Disruption of Model Cell Membranes

PubMed Central

Moghadam, Babak Y.; Hou, Wen-Che; Corredor, Charlie; Westerhoff, Paul; Posner, Jonathan D.

2012-01-01

Lipid bilayers are biomembranes common to cellular life and constitute a continuous barrier between cells and their environment. Understanding the interaction of engineered nanomaterials (ENMs) with lipid bilayers is an important step toward predicting subsequent biological effects. In this study, we assess the effect of varying the surface functionality and concentration of 10 nm-diameter gold (Au) and titanium dioxide (TiO2) ENMs on the disruption of negatively charged lipid bilayer vesicles (liposomes) using a dye leakage assay. Our findings show that Au ENMs having both positive and negative surface charge induce leakage that reaches a steady state after several hours. Positively charged particles with identical surface functionality and different core composition show similar leakage effects and result in faster and greater leakage than negatively charged particles, which suggests that surface functionality, not particle core composition, is a critical factor in determining the interaction between ENMs and lipid bilayers. The results suggest that particles permanently adsorb to bilayers and that only one positively charged particle is required to disrupt a liposome and trigger leakage of its entire contents in contrast to mellitin molecules, the most widely studied membrane lytic peptide, which requires hundred of molecules to generate leakage. PMID:22921268

Surface charge effects in protein adsorption on nanodiamonds.

PubMed

Aramesh, M; Shimoni, O; Ostrikov, K; Prawer, S; Cervenka, J

2015-03-19

Understanding the interaction of proteins with charged diamond nanoparticles is of fundamental importance for diverse biomedical applications. Here we present a thorough study of protein binding, adsorption kinetics and structure on strongly positively (hydrogen-terminated) and negatively (oxygen-terminated) charged nanodiamond particles using a quartz crystal microbalance by dissipation and infrared spectroscopy. By using two model proteins (bovine serum albumin and lysozyme) of different properties (charge, molecular weight and rigidity), the main driving mechanism responsible for the protein binding to the charged nanoparticles was identified. Electrostatic interactions were found to dominate the protein adsorption dynamics, attachment and conformation. We developed a simple electrostatic model that can qualitatively explain the observed adsorption behaviour based on charge-induced pH modifications near the charged nanoparticle surfaces. Under neutral conditions, the local pH around the positively and negatively charged nanodiamonds becomes very high (11-12) and low (1-3) respectively, which has a profound impact on the protein charge, hydration and affinity to the nanodiamonds. Small proteins (lysozyme) were found to form multilayers with significant conformational changes to screen the surface charge, while larger proteins (albumin) formed monolayers with minor conformational changes. The findings of this study provide a step forward toward understanding and eventually predicting nanoparticle interactions with biofluids.

Optimizing multi-step B-side charge separation in photosynthetic reaction centers from Rhodobacter capsulatus

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

Faries, Kaitlyn M.; Kressel, Lucas L.; Dylla, Nicholas P.

Using high-throughput methods for mutagenesis, protein isolation and charge-separation functionality, we have assayed 40 Rhodobacter capsulatus reaction center (RC) mutants for their P+ QB- yield (P is a dimer of bacteriochlorophylls and Q is a ubiquinone) as produced using the normally inactive B-side cofactors BB and HB (where B is a bacteriochlorophyll and H is a bacteriopheophytin). Two sets of mutants explore all possible residues at M131 (M polypeptide, native residue Val near HB) in tandem with either a fixed His or a fixed Asn at L181 (L polypeptide, native residue Phe near BB). A third set of mutants exploresmore » all possible residues at L181 with a fixed Glu at M131 that can form a hydrogen bond to HB. For each set of mutants, the results of a rapid millisecond screening assay that probes the yield of P+ QB- are compared among that set and to the other mutants reported here or previously. For a subset of eight mutants, the rate constants and yields of the individual B-side electron transfer processes are determined via transient absorption measurements spanning 100 fs to 50 μs. The resulting ranking of mutants for their yield of P+ QB- from ultrafast experiments is in good agreement with that obtained from the millisecond screening assay, further validating the efficient, high-throughput screen for B-side transmembrane charge separation. Results from mutants that individually show progress toward optimization of P+ HB- → P+ QB- electron transfer or initial P* → P+ HB- conversion highlight unmet challenges of optimizing both processes simultaneously.« less

The local surface plasmon resonance property and refractive index sensitivity of metal elliptical nano-ring arrays

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

Lin, Weihua, E-mail: linwh-whu@hotmail.com; Wang, Qian; Dong, Anhua

2014-11-15

In this paper, we systematically investigate the optical property and refractive index sensitivity (RIS) of metal elliptical nano-ring (MENR) arranged in rectangle lattice by finite-difference time-domain method. Eight kinds of considered MENRs are divided into three classes, namely fixed at the same outer size, at the same inner size, and at the same middle size. All MENR arrays show a bonding mode local surface plasmon resonance (LSPR) peak in the near-infrared region under longitudinal and transverse polarizations, and lattice diffraction enhanced LSPR peaks emerge, when the LSPR peak wavelength (LSPRPW) matches the effective lattice constant of the array. The LSPRPWmore » is determined by the charge moving path length, the parallel and cross interactions induced by the stable distributed charges, and the moving charges inter-attraction. High RIS can be achieved by small particle distance arrays composed of MENRs with big inner size and small ring-width. On the other hand, for a MENR array, the comprehensive RIS (including RIS and figure of merit) under transverse polarization is superior to that under longitudinal polarization. Furthermore, on condition that compared arrays are fixed at the same lattice constant, the phenomenon that the RIS of big ring-width MENR arrays may be higher than that of small ring-width MENR arrays only appears in the case of compared arrays with relatively small lattice constant and composed of MENRs fixed at the same inner size simultaneously. Meanwhile, the LSPRPW of the former MENR arrays is also larger than that of the latter MENR arrays. Our systematic results may help experimentalists work with this type of systems.« less

Sulfonium Ion Derivatization, Isobaric Stable Isotope Labeling and Data Dependent CID- and ETD-MS/MS for Enhanced Phosphopeptide Quantitation, Identification and Phosphorylation Site Characterization

PubMed Central

Lu, Yali; Zhou, Xiao; Stemmer, Paul M.; Reid, Gavin E.

2014-01-01

An amine specific peptide derivatization strategy involving the use of novel isobaric stable isotope encoded ‘fixed charge’ sulfonium ion reagents, coupled with an analysis strategy employing capillary HPLC, ESI-MS, and automated data dependent ion trap CID-MS/MS, -MS3, and/or ETD-MS/MS, has been developed for the improved quantitative analysis of protein phosphorylation, and for identification and characterization of their site(s) of modification. Derivatization of 50 synthetic phosphopeptides with S,S′-dimethylthiobutanoylhydroxysuccinimide ester iodide (DMBNHS), followed by analysis using capillary HPLC-ESI-MS, yielded an average 2.5-fold increase in ionization efficiencies and a significant increase in the presence and/or abundance of higher charge state precursor ions compared to the non-derivatized phosphopeptides. Notably, 44% of the phosphopeptides (22 of 50) in their underivatized states yielded precursor ions whose maximum charge states corresponded to +2, while only 8% (4 of 50) remained at this maximum charge state following DMBNHS derivatization. Quantitative analysis was achieved by measuring the abundances of the diagnostic product ions corresponding to the neutral losses of ‘light’ (S(CH3)2) and ‘heavy’ (S(CD3)2) dimethylsulfide exclusively formed upon CID-MS/MS of isobaric stable isotope labeled forms of the DMBNHS derivatized phosphopeptides. Under these conditions, the phosphate group stayed intact. Access for a greater number of peptides to provide enhanced phosphopeptide sequence identification and phosphorylation site characterization was achieved via automated data-dependent CID-MS3 or ETD-MS/MS analysis due to the formation of the higher charge state precursor ions. Importantly, improved sequence coverage was observed using ETD-MS/MS following introduction of the sulfonium ion fixed charge, but with no detrimental effects on ETD fragmentation efficiency. PMID:21952753

Negative measurement sensitivity values of planar capacitive imaging probes

NASA Astrophysics Data System (ADS)

Yin, Xiaokang; Chen, Guoming; Li, Wei; Hutchins, David

2014-02-01

The measurement sensitivity distribution of planar capacitive imaging (CI) probes describes how effectively each region in the sensing area is contributing to the measured charge signal on the sensing electrode. It can be used to determine the imaging ability of a CI probe. It is found in previous work that, there are regions in the sensing area where the change of the charge output and the change of targeting physical parameter are of opposite trends. This opposite correlation implies that the measurement sensitivity values in such regions are negative. In this work, the cause of negative sensitivity is discussed. Experiments are also designed and performed so as to verify the existence of negative sensitivity and study the factors that may affect the negative sensitivity distributions.

Assessment and Control of Spacecraft Charging Risks on the International Space Station

NASA Technical Reports Server (NTRS)

Koontz, Steve; Edeen, Marybeth; Spetch, William; Dalton, Penni; Keening, Thomas

2003-01-01

Electrical interactions between the F2 region ionospheric plasma and the 160V photovoltaic (PV) electrical power system on the International Space Station (ISS) can produce floating potentials (FP) on the ISS conducting structure of greater magnitude than are usually observed on spacecraft in low-Earth orbit. Flight through the geomagnetic field also causes magnetic induction charging of ISS conducting structure. Charging processes resulting from interaction of ISS with auroral electrons may also contribute to charging albeit rarely. The magnitude and frequency of occurrence of possibly hazardous charging events depends on the ISS assembly stage (six more 160V PV arrays will be added to ISS), ISS flight configuration, ISS position (latitude and longitude), and the natural variability in the ionospheric flight environment. At present, ISS is equipped with two plasma contactors designed to control ISS FP to within 40 volts of the ambient F2 plasma. The negative-polarity grounding scheme utilized in the ISS 160V power system leads, naturally, to negative values of ISS FP. A negative ISS structural FP leads to application of electrostatic fields across the dielectrics that separate conducting structure from the ambient F2 plasma, thereby enabling dielectric breakdown and arcing. Degradation of some thermal control coatings and noise in electrical systems can result. Continued review and evaluation of the putative charging hazards, as required by the ISS Program Office, revealed that ISS charging could produce a risk of electric shock to the ISS crew during extra vehicular activity. ISS charging risks are being evaluated in ongoing ISS charging measurements and analysis campaigns. The results of ISS charging measurements are combined with a recently developed detailed model of the ISS charging process and an extensive analysis of historical ionospheric variability data, to assess ISS charging risks using Probabilistic Risk Assessment (PRA) methods. The PRA analysis (estimated frequency of occurrence and severity of the charging hazards) are then used to select the hazard control strategy that provides the best overall safety and mission success environment for ISS and the ISS crew. This paper presents: 1) a summary of ISS spacecraft charging analysis, measurements, observations made to date, 2) plans for future ISS spacecraft charging measurement campaigns, and 3) a detailed discussion of the PRA strategy used to assess ISS spacecraft charging risks and select charging hazard control strategies

Assessment and Control of International Space Station Spacecraft Charging Risks

NASA Astrophysics Data System (ADS)

Koontz, S.; Edeen, M.; Spetch, W.; Dalton, P.; Keeping, T.; Minow, J.

2003-12-01

Electrical interactions between the F2 region ionospheric plasma and the 160V photovoltaic (PV) electrical power system on the International Space Station (ISS) can produce floating potentials (FP) on ISS conducting structure of greater magnitude than are usually observed on spacecraft in low-Earth orbit. Flight through the geomagnetic field also causes magnetic induction charging of ISS conducting structure. Charging processes resulting from interaction of ISS with auroral electrons may also contribute to charging, albeit rarely. The magnitude and frequency of occurrence of possibly hazardous charging events depends on the ISS assembly stage (six more 160V PV arrays will be added to ISS), ISS flight configuration, ISS position (latitude and longitude), and the natural variability in the ionospheric flight environment. At present, ISS is equipped with two plasma contactors designed to control ISS FP to within 40 volts of the ambient F2 plasma. The negative-polarity grounding scheme utilized in the ISS 160V power system leads, naturally, to negative values of ISS FP. A negative ISS structural FP leads to application of electrostatic fields across the dielectrics that separate conducting structure from the ambient F2 plasma, thereby enabling dielectric breakdown and arcing. Degradation of some thermal control coatings and noise in electrical systems can result. Continued review and evaluation of the putative charging hazards, as required by the ISS Program Office, revealed that ISS charging could produce a risk of electric shock to the ISS crew during extra vehicular activity. ISS charging risks are being evaluated in ongoing ISS charging measurements and analysis campaigns. The results of ISS charging measurements are combined with a recently developed detailed model of the ISS charging process and an extensive analysis of historical ionospheric variability data, to assess ISS charging risks using Probabilistic Risk Assessment (PRA) methods. The PRA analysis (estimated frequency of occurrence and severity of the charging hazards) are then used to select the hazard control strategy that provides the best overall safety and mission success environment for ISS and the ISS crew. This paper presents: 1) a summary of ISS spacecraft charging analysis, measurements, observations made to date, 2) plans for future ISS spacecraft charging measurement campaigns, and 3) a detailed discussion of the PRA strategy used to assess ISS spacecraft charging risks and select charging hazard control strategies.

Protein charge ladders reveal that the net charge of ALS-linked superoxide dismutase can be different in sign and magnitude from predicted values

PubMed Central

Shi, Yunhua; Abdolvahabi, Alireza; Shaw, Bryan F

2014-01-01

This article utilized “protein charge ladders”—chemical derivatives of proteins with similar structure, but systematically altered net charge—to quantify how missense mutations that cause amyotrophic lateral sclerosis (ALS) affect the net negative charge (Z) of superoxide dismutase-1 (SOD1) as a function of subcellular pH and Zn2+ stoichiometry. Capillary electrophoresis revealed that the net charge of ALS-variant SOD1 can be different in sign and in magnitude—by up to 7.4 units per dimer at lysosomal pH—than values predicted from standard pKa values of amino acids and formal oxidation states of metal ions. At pH 7.4, the G85R, D90A, and G93R substitutions diminished the net negative charge of dimeric SOD1 by up to +2.29 units more than predicted; E100K lowered net charge by less than predicted. The binding of a single Zn2+ to mutant SOD1 lowered its net charge by an additional +2.33 ± 0.01 to +3.18 ± 0.02 units, however, each protein regulated net charge when binding a second, third, or fourth Zn2+ (ΔZ < 0.44 ± 0.07 per additional Zn2+). Both metalated and apo-SOD1 regulated net charge across subcellular pH, without inverting from negative to positive at the theoretical pI. Differential scanning calorimetry, hydrogen-deuterium exchange, and inductively coupled plasma mass spectrometry confirmed that the structure, stability, and metal content of mutant proteins were not significantly affected by lysine acetylation. Measured values of net charge should be used when correlating the biophysical properties of a specific ALS-variant SOD1 protein with its observed aggregation propensity or clinical phenotype. PMID:25052939

Versatile organic (fullerene)-inorganic (CdTe nanoparticle) nanoensembles.

PubMed

Guldi, Dirk M; Zilbermann, Israel; Anderson, Greg; Kotov, Nicholas A; Tagmatarchis, Nikos; Prato, Maurizio

2004-11-10

Novel organic (positively charged fullerene)-inorganic (negatively charged CdTe nanoparticle) nanoensembles were devised through electrostatic interactions and probed as versatile donor-acceptor hybrids. Photoirradiation of their homogeneous solutions, containing the electrostatically packed components, let to very long-lived (1.3 ms) charge separated states.

Nanocomplexes of Photolabile Polyelectrolyte and Upconversion Nanoparticles for Near-Infrared Light-Triggered Payload Release.

PubMed

Xiang, Jun; Ge, Feijie; Yu, Bing; Yan, Qiang; Shi, Feng; Zhao, Yue

2018-06-07

A new approach to encapsulating charged cargo molecules into a nanovector and subsequently using near-infrared (NIR) light to trigger the release is demonstrated. NIR light-responsive nanovector was prepared through electrostatic interaction-driven complexation between negatively charged silica-coated upconversion nanoparticles (UCNP@silica, 87 nm hydrodynamic diameter, polydispersity index ∼0.05) and a positively charged UV-labile polyelectrolyte bearing pendants of poly(ethylene glycol) and o-nitrobenzyl side groups; whereas charged fluorescein (FLU) was loaded through a co-complexation process. By controlling the amount of polyelectrolyte, UCNP@silica can be covered by the polymer, whereas remaining dispersed in aqueous solution. Under 980 nm laser excitation, UV light emitted by UCNP is absorbed by photolytic side groups within polyelectrolyte, which results in cleavage of o-nitrobenzyl groups and formation of carboxylic acid groups. Such NIR light-induced partial reversal of positive charge to negative charge on the polyelectrolyte layer disrupts the equilibrium among UCNP@silica, polyelectrolyte, and FLU and, consequently, leads to release of FLU molecules.

Numerical modelling of needle-grid electrodes for negative surface corona charging system

NASA Astrophysics Data System (ADS)

Zhuang, Y.; Chen, G.; Rotaru, M.

2011-08-01

Surface potential decay measurement is a simple and low cost tool to examine electrical properties of insulation materials. During the corona charging stage, a needle-grid electrodes system is often used to achieve uniform charge distribution on the surface of the sample. In this paper, a model using COMSOL Multiphysics has been developed to simulate the gas discharge. A well-known hydrodynamic drift-diffusion model was used. The model consists of a set of continuity equations accounting for the movement, generation and loss of charge carriers (electrons, positive and negative ions) coupled with Poisson's equation to take into account the effect of space and surface charges on the electric field. Four models with the grid electrode in different positions and several mesh sizes are compared with a model that only has the needle electrode. The results for impulse current and surface charge density on the sample clearly show the effect of the extra grid electrode with various positions.

Effect of surface charge density on the affinity of oxide nanoparticles for the vapor-water interface.

PubMed

Brown, Matthew A; Duyckaerts, Nicolas; Redondo, Amaia Beloqui; Jordan, Inga; Nolting, Frithjof; Kleibert, Armin; Ammann, Markus; Wörner, Hans Jakob; van Bokhoven, Jeroen A; Abbas, Zareen

2013-04-23

Using in-situ X-ray photoelectron spectroscopy at the vapor-water interface, the affinity of nanometer-sized silica colloids to adsorb at the interface is shown to depend on colloid surface charge density. In aqueous suspensions at pH 10 corrected Debye-Hückel theory for surface complexation calculations predict that smaller silica colloids have increased negative surface charge density that originates from enhanced screening of deprotonated silanol groups (≡Si-O(-)) by counterions in the condensed ion layer. The increased negative surface charge density results in an electrostatic repulsion from the vapor-water interface that is seen to a lesser extent for larger particles that have a reduced charge density in the XPS measurements. We compare the results and interpretation of the in-situ XPS and corrected Debye-Hückel theory for surface complexation calculations with traditional surface tension measurements. Our results show that controlling the surface charge density of colloid particles can regulate their adsorption to the interface between two dielectrics.

Ordered adsorption of coagulation factor XII on negatively charged polymer surfaces probed by sum frequency generation vibrational spectroscopy.

PubMed

Chen, Xiaoyun; Wang, Jie; Paszti, Zoltan; Wang, Fulin; Schrauben, Joel N; Tarabara, Volodymyr V; Schmaier, Alvin H; Chen, Zhan

2007-05-01

Electrostatic interactions between negatively charged polymer surfaces and factor XII (FXII), a blood coagulation factor, were investigated by sum frequency generation (SFG) vibrational spectroscopy, supplemented by several analytical techniques including attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), quartz crystal microbalance (QCM), zeta-potential measurement, and chromogenic assay. A series of sulfonated polystyrenes (sPS) with different sulfonation levels were synthesized as model surfaces with different surface charge densities. SFG spectra collected from FXII adsorbed onto PS and sPS surfaces with different surface charge densities showed remarkable differences in spectral features and especially in spectral intensity. Chromogenic assay experiments showed that highly charged sPS surfaces induced FXII autoactivation. ATR-FTIR and QCM results indicated that adsorption amounts on the PS and sPS surfaces were similar even though the surface charge densities were different. No significant conformational change was observed from FXII adsorbed onto surfaces studied. Using theoretical calculations, the possible contribution from the third-order nonlinear optical effect induced by the surface electric field was evaluated, and it was found to be unable to yield the SFG signal enhancement observed. Therefore it was concluded that the adsorbed FXII orientation and ordering were the main reasons for the remarkable SFG amide I signal increase on sPS surfaces. These investigations indicate that negatively charged surfaces facilitate or induce FXII autoactivation on the molecular level by imposing specific orientation and ordering on the adsorbed protein molecules.

Interactions and diffusion in fine-stranded β-lactoglobulin gels determined via FRAP and binding.

PubMed

Schuster, Erich; Hermansson, Anne-Marie; Ohgren, Camilla; Rudemo, Mats; Lorén, Niklas

2014-01-07

The effects of electrostatic interactions and obstruction by the microstructure on probe diffusion were determined in positively charged hydrogels. Probe diffusion in fine-stranded gels and solutions of β-lactoglobulin at pH 3.5 was determined using fluorescence recovery after photobleaching (FRAP) and binding, which is widely used in biophysics. The microstructures of the β-lactoglobulin gels were characterized using transmission electron microscopy. The effects of probe size and charge (negatively charged Na2-fluorescein (376Da) and weakly anionic 70kDa FITC-dextran), probe concentration (50 to 200 ppm), and β-lactoglobulin concentration (9% to 12% w/w) on the diffusion properties and the electrostatic interaction between the negatively charged probes and the positively charged gels or solutions were evaluated. The results show that the diffusion of negatively charged Na2-fluorescein is strongly influenced by electrostatic interactions in the positively charged β-lactoglobulin systems. A linear relationship between the pseudo-on binding rate constant and the β-lactoglobulin concentration for three different probe concentrations was found. This validates an important assumption of existing biophysical FRAP and binding models, namely that the pseudo-on binding rate constant equals the product of the molecular binding rate constant and the concentration of the free binding sites. Indicators were established to clarify whether FRAP data should be analyzed using a binding-diffusion model or an obstruction-diffusion model. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Correlation between octanol/water and liposome/water distribution coefficients and drug absorption of a set of pharmacologically active compounds.

PubMed

Esteves, Freddy; Moutinho, Carla; Matos, Carla

2013-06-01

Absorption and consequent therapeutic action are key issues in the development of new drugs by the pharmaceutical industry. In this sense, different models can be used to simulate biological membranes to predict the absorption of a drug. This work compared the octanol/water and the liposome/water models. The parameters used to relate the two models were the distribution coefficients between liposomes and water and octanol and water and the fraction of drug orally absorbed. For this study, 66 drugs were collected from literature sources and divided into four groups according to charge and ionization degree: neutral; positively charged; negatively charged; and partially ionized/zwitterionic. The results show a satisfactory linear correlation between the octanol and liposome systems for the neutral (R²= 0.9324) and partially ionized compounds (R²= 0.9367), contrary to the positive (R²= 0.4684) and negatively charged compounds (R²= 0.1487). In the case of neutral drugs, results were similar in both models because of the high fraction orally absorbed. However, for the charged drugs (positively, negatively, and partially ionized/zwitterionic), the liposomal model has a more-appropriate correlation with absorption than the octanol model. These results show that the neutral compounds only interact with membranes through hydrophobic bonds, whereas charged drugs favor electrostatic interactions established with the liposomes. With this work, we concluded that liposomes may be a more-appropriate biomembrane model than octanol for charged compounds.

Carbon Dioxide Removal by Salty Aerosols

NASA Astrophysics Data System (ADS)

Gokturk, H.

2016-12-01

Aerosols consisting of salt ions dissolved in water are observed in nature as sea spray particles generated by breaking waves. Such aerosols can be also generated artificially by spraying seawater to the atmosphere to create clouds, which was suggested as a method of solar radiation management (SRM). Salty aerosols can be utilized not only for SRM, but also for carbon dioxide removal from the atmosphere, if salt ions carrying charges -2 or more negative are added to the seawater. CO2 is a very stable molecule where carbon to oxygen double bond has a bond strength of 8.3 eV (190 kcal/mol). Therefore the approach chosen here to modify CO2 is to further oxidize it to CO3. Quantum mechanical calculations indicate that CO2 reacts readily with hydroxyl minus ion (OH-) or oxygen double minus ion (O-) to form HCO3- or CO3-, respectively. What is studied in this paper is the utilization of hydrated negative salt ions to create OH- and possibly even O-. The negative ions chosen are chlorine minus ion (Cl-), sulfate double minus ion (SO4-), phosphate triple minus ion (PO4--) and silicate quadruple minus ion (SiO4--). The former two ions exist in seawater, but the latter two ions do not, though they are available as part of water soluble salts such as potassium phosphate. Using quantum mechanical calculations, following reactions were investigated: R1: (Cl-) + H2O => HCl + (OH-), R2: (SO4-) + H2O => (HSO4-) + (OH-), R3: (PO4--) + H2O => (HPO4-) + (OH-), R4: (SiO4--) + H2O => (HSiO4--) + (OH-), R5: (HPO4-) + H2O => (H2PO4-) + (OH-), R6: (HSiO4--) + H2O => (H2SiO4-) + (OH-), R7: (H2SiO4-) + H2O => (H3SiO4-) + (OH-), R8: (SiO4--) + H2O => (H2SiO4-) + (O-). Results indicate that singly charged negative salt ions, such as Cl- in R1, cannot create OH-. Doubly charged negative salt ions, such as SO4- in R2, can create OH-, though the amount of SO4- in seawater is relatively small. Triply or quadruply charged negative ions are even more favorable than doubly charged ions in creating OH- (R3, R4, R6). Quadruply charged negative ions can also create O- (R8), however in practice O- is likely to react with other water molecules to create more OH-. In conclusion, seawater fortified with highly charged negative salt ions and sprayed into the atmosphere has the potential to create aerosols containing OH- which can react with the CO2 and modify it to a carbonate.

Effect of Primary-Ion Current Density on Charge Compensation in SIMS Analysis of a Quartz Glass

NASA Astrophysics Data System (ADS)

Inoue, Kazuyuki; Isogai, Akio

1988-05-01

In secondary ion mass spectrometry (SIMS) analysis of a quartz glass by means of negative ion bombardment, the effect of the negative ion current density (Ji) has been investigated. The results show that under lower Ji (<20 μA/cm2), time is required to compensate for the surface charge and the time is inversely proportional to Ji.

Radiation transport codes for potential applications related to radiobiology and radiotherapy using protons, neutrons, and negatively charged pions

NASA Technical Reports Server (NTRS)

Armstrong, T. W.

1972-01-01

Several Monte Carlo radiation transport computer codes are used to predict quantities of interest in the fields of radiotherapy and radiobiology. The calculational methods are described and comparisions of calculated and experimental results are presented for dose distributions produced by protons, neutrons, and negatively charged pions. Comparisons of calculated and experimental cell survival probabilities are also presented.

Double layer of platinum electrodes: Non-monotonic surface charging phenomena and negative double layer capacitance

NASA Astrophysics Data System (ADS)

Huang, Jun; Zhou, Tao; Zhang, Jianbo; Eikerling, Michael

2018-01-01

In this study, a refined double layer model of platinum electrodes accounting for chemisorbed oxygen species, oriented interfacial water molecules, and ion size effects in solution is presented. It results in a non-monotonic surface charging relation and a peculiar capacitance vs. potential curve with a maximum and possibly negative values in the potential regime of oxide-formation.

Coaxial charged particle energy analyzer

NASA Technical Reports Server (NTRS)

Kelly, Michael A. (Inventor); Bryson, III, Charles E. (Inventor); Wu, Warren (Inventor)

2011-01-01

A non-dispersive electrostatic energy analyzer for electrons and other charged particles having a generally coaxial structure of a sequentially arranged sections of an electrostatic lens to focus the beam through an iris and preferably including an ellipsoidally shaped input grid for collimating a wide acceptance beam from a charged-particle source, an electrostatic high-pass filter including a planar exit grid, and an electrostatic low-pass filter. The low-pass filter is configured to reflect low-energy particles back towards a charged particle detector located within the low-pass filter. Each section comprises multiple tubular or conical electrodes arranged about the central axis. The voltages on the lens are scanned to place a selected energy band of the accepted beam at a selected energy at the iris. Voltages on the high-pass and low-pass filters remain substantially fixed during the scan.

Polarization and interface charge coupling in ferroelectric/AlGaN/GaN heterostructure

NASA Astrophysics Data System (ADS)

Zhang, Min; Kong, Yuechan; Zhou, Jianjun; Xue, Fangshi; Li, Liang; Jiang, Wenhai; Hao, Lanzhong; Luo, Wenbo; Zeng, Huizhong

2012-03-01

Asymmetrical shift behaviors of capacitance-voltage (C-V) curve with opposite direction are observed in two AlGaN/GaN metal-ferroelectric-semiconductor (MFS) heterostructures with Pb(Zr,Ti)O3 and LiNbO3 gate dielectrics. By incorporating the switchable polar nature of the ferroelectric into a self-consistent calculation, the coupling effect between the ferroelectric and the interface charges is disclosed. The opposite initial orientation of ferroelectric dipoles determined by the interface charges is essentially responsible for the different C-V characteristics. A critical fixed charge density of -1.27 × 1013cm-2 is obtained, which plays a key role in the dependence of the C-V characteristic on the ferroelectric polarization. The results pave the way for design of memory devices based on MFS structure with heteropolar interface.

Impact of Distribution Feeders that do not have Voltage Regulators on the number of Charged Electric Vehicles using IEEE 34 Bus Test Feeder

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

Allehyani, Ahmed; Beshir, Mohammed

Voltage regulators help maintain an acceptable voltage profile for the system. This paper discusses the effect of installing voltage regulators to the system to fix the voltage drop resulting from the electrical vehicles loading increase when they are being charged. The effect will be studied in the afternoon, when the peak load occurs, using the IEEE 34 bus test feeder. First, only one spot node is used to charge the electric vehicles while a voltage regulator is present. Second, five spot nodes are loaded at the same time to charge the electric vehicles while voltage regulators are installed at eachmore » node. After that, the impact of electric vehicles on distribution feeders that do not have voltage regulators will appear.« less

Relating Silica Scaling in Reverse Osmosis to Membrane Surface Properties.

PubMed

Tong, Tiezheng; Zhao, Song; Boo, Chanhee; Hashmi, Sara M; Elimelech, Menachem

2017-04-18

We investigated the relationship between membrane surface properties and silica scaling in reverse osmosis (RO). The effects of membrane hydrophilicity, free energy for heterogeneous nucleation, and surface charge on silica scaling were examined by comparing thin-film composite polyamide membranes grafted with a variety of polymers. Results show that the rate of silica scaling was independent of both membrane hydrophilicity and free energy for heterogeneous nucleation. In contrast, membrane surface charge demonstrated a strong correlation with the extent of silica scaling (R 2 > 0.95, p < 0.001). Positively charged membranes significantly facilitated silica scaling, whereas a more negative membrane surface charge led to reduced scaling. This observation suggests that deposition of negatively charged silica species on the membrane surface plays a critical role in silica scale formation. Our findings provide fundamental insights into the mechanisms governing silica scaling in reverse osmosis and highlight the potential of membrane surface modification as a strategy to reduce silica scaling.

The impact of prescription charges on asthma patients is uneven and unpredictable: evidence from qualitative interviews.

PubMed

Schafheutle, Ellen I

2009-12-01

To explore whether, and how, prescription charges affect asthma patients' disease management behaviour. Thirty qualitative interviews. Interviewees were aged between 21 and 59, 21 were women, 24 were paying individual prescription charges, and six had prepayment certificates (PPCs). Most had a beta2-agonist 'reliever' and a steroid 'preventer' inhaler. Prescription charges posed affordability issues for some, and for two patients cost-related reduction in 'preventer' use affected asthma control negatively. Many described various ways of keeping medication cost down. Affordability issues, negative views on paying charges, and whether interviewees viewed their asthma medication as essential, were influential factors. Steroid inhalers were viewed more commonly as being less essential and affected by cost. The episodic nature of asthma meant that predicting benefit from PPCs was difficult. This study strengthens existing evidence that medication cost is a factor in asthma patients' management decisions, with a potential cost-related impact on asthma control.

Plasma bullet current measurements in a free-stream helium capillary jet

NASA Astrophysics Data System (ADS)

Oh, Jun-Seok; Walsh, James L.; Bradley, James W.

2012-06-01

A commercial current monitor has been used to measure the current associated with plasma bullets created in both the positive and negative half cycles of the sinusoidal driving voltage sustaining a plasma jet. The maximum values of the positive bullet current are typically ˜750 µA and persist for 10 µs, while the peaks in the negative current of several hundred μA are broad, persisting for about 40 µs. From the time delay of the current peaks with increasing distance from the jet nozzle, an average bullet propagation speed has been measured; the positive and negative bullets travel at 17.5 km s-1 and 3.9 km s-1 respectively. The net space charge associated with the bullet(s) has also been calculated; the positive and negative bullets contain a similar net charge of the order of 10-9 C measured at all monitor positions, with estimated charged particle densities nb of ˜1010-1011 cm-3 in the bullet.

Translocation of a heterogeneous polymer

PubMed Central

Mirigian, Stephen; Wang, Yanbo; Muthukumar, Murugappan

2012-01-01

We present results on the sequence dependence of translocation kinetics for a partially charged heteropolymer moving through a very thin pore using theoretical tools and Langevin dynamics simulational techniques. The chain is composed of two types of monomers of differing frictional interaction with the pore and charge. We present exact analytical expressions for passage probability, mean first passage time, and mean successful passage times for both reflecting/absorbing and absorbing/absorbing boundary conditions, showing rich and unexpected dependence of translocation behavior on charge fraction, distribution along the chain, and electric field configuration. We find excellent qualitative and good quantitative agreement between theoretical and simulation results. Surprisingly, there emerges a threshold charge fraction of a diblock copolymer beyond which the success rate of translocation is independent of charge fraction. Also, the mean successful translocation time of a diblock copolymer displays non-monotonic behavior with increasing length of the charged block; there is an optimum length of the charged block where the mean translocation rate is the slowest; and there can be a substantial range of higher charge fractions which make the translocation slower than even a minimally charged chain. Additionally, we find for a fixed total charge on the chain, finer distribution along the backbone significantly decreases mean translocation time. PMID:22897308

46 CFR 162.161-4 - Construction.

Code of Federal Regulations, 2014 CFR

2014-10-01

...: SPECIFICATIONS AND APPROVAL ENGINEERING EQUIPMENT Fixed Clean Agent Fire Extinguishing Systems § 162.161-4... mechanical or pneumatic means. (d) Automatically actuated systems must be released by pneumatic or fusible... actuation and have a remote backup manual mechanical actuator. (f) Each container charged with nitrogen must...

46 CFR 162.161-4 - Construction.

Code of Federal Regulations, 2012 CFR

2012-10-01

...: SPECIFICATIONS AND APPROVAL ENGINEERING EQUIPMENT Fixed Clean Agent Fire Extinguishing Systems § 162.161-4... mechanical or pneumatic means. (d) Automatically actuated systems must be released by pneumatic or fusible... actuation and have a remote backup manual mechanical actuator. (f) Each container charged with nitrogen must...

46 CFR 162.161-4 - Construction.

Code of Federal Regulations, 2013 CFR

2013-10-01

...: SPECIFICATIONS AND APPROVAL ENGINEERING EQUIPMENT Fixed Clean Agent Fire Extinguishing Systems § 162.161-4... mechanical or pneumatic means. (d) Automatically actuated systems must be released by pneumatic or fusible... actuation and have a remote backup manual mechanical actuator. (f) Each container charged with nitrogen must...

46 CFR 520.2 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... basic ocean freight rate. BTA means the Commission's Bureau of Trade Analysis or its successor bureau... carriers which provides for the fixing of and adherence to uniform tariff rates, charges, practices and... via dial-up telecommunications or a network link and interacts with the carrier's or publisher's...

46 CFR 520.2 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... basic ocean freight rate. BTA means the Commission's Bureau of Trade Analysis or its successor bureau... carriers which provides for the fixing of and adherence to uniform tariff rates, charges, practices and... via dial-up telecommunications or a network link and interacts with the carrier's or publisher's...

46 CFR 520.2 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... basic ocean freight rate. BTA means the Commission's Bureau of Trade Analysis or its successor bureau... carriers which provides for the fixing of and adherence to uniform tariff rates, charges, practices and... via dial-up telecommunications or a network link and interacts with the carrier's or publisher's...

46 CFR 520.2 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... basic ocean freight rate. BTA means the Commission's Bureau of Trade Analysis or its successor bureau... carriers which provides for the fixing of and adherence to uniform tariff rates, charges, practices and... via dial-up telecommunications or a network link and interacts with the carrier's or publisher's...

46 CFR 520.2 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... basic ocean freight rate. BTA means the Commission's Bureau of Trade Analysis or its successor bureau... carriers which provides for the fixing of and adherence to uniform tariff rates, charges, practices and... via dial-up telecommunications or a network link and interacts with the carrier's or publisher's...

Fully redundant mechanical release actuator

NASA Technical Reports Server (NTRS)

Lucy, Melvin H. (Inventor)

1987-01-01

A system is described for performing a mechanical release function exhibiting low shock. This system includes two pyrotechnic detents fixed mounted in opposing axial alignment within a cylindrical housing having two mechanical bellows. Two mechanical bellow assemblies, each having one end hermetically bonded to the housing and the other to the respective actuator pin extending from either end of the housing, ensure that all outgassing and contamination from the operation of the pyrotechnic devices will be contained within the housing and bellows. The pin on one end of the assembly is fixed mounted and supported, via a bolt or ball-and-socket joint so that when the charge corresponding to that pin ignites, the entire assembly will exhibit rectilinear movement, including the opposing pin providing the unlatching motion. The release detent pin is supported by a linear bearing and when its corresponding pyrotechnic charge ignites the pin is retracted within the housing producing the same unlatching motion without movement of the entire assembly, thus providing complete mechanical, electrical and pyrotechnic redundancy for the unlatching pin.

Photoinduced electron transfer in fixed distance chlorophyll-quinone donor-acceptor molecules

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

Wasielewski, M.R.; Johnson, D.G.; Svec, W.A.

1987-01-01

A series of fixed distance chlorophyll-quinone donor-acceptor molecules have been prepared. The donor consists of either methyl pyropheophorbide a or methyl pyrochlorophyllide a, while the acceptor is either benzoquinone or naphthoquinone. The acceptors are fused to a triptycene spacer group, which in turn is attached to the donors at their vinyl groups. Picosecond transient absorption measurements have been used to identify electron transfer from the lowest excited singlet state of the donor to the acceptor as the mechanism of fluorescence quenching in these molecules. The charge separation rate constants increase from 2 x 10/sup 10/ s/sup -1/ to 4 xmore » 10/sup 11/ s/sup -1/ as the free energy of charge separation increases, while the radical pair recombination rate constants decrease from 1.2 x 10/sup 11/ s/sup -1/ to 2 x 10/sup 9/ s/sup -1/ as the free energy of recombination increases. The resulting total reorganization energy lambda = 0.9 eV.« less

Biosorption of metal ions from aqueous solutions

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

Chen, Jiaping; Yiacoumi, Sotira

1997-01-01

Copper biosorption from aqueous solutions by calcium alginate is reported in this paper. The experimental section includes potentiometric titrations of biosorbents, batch equilibrium and kinetic studies of copper biosorption, as well as fixed-bed biosorption experiments. The potentiometric titration results show that the surface charge increases with decreasing pH. The biosorption of copper strongly depends on solution pH; the metal ion binding increases from 0 to 90 percent in pH ranging from 1.5 to 5.0. In addition, a decrease in ionic strength results in an increase of copper ion removal. Kinetic studies indicate that mass transfer plays an important role inmore » the biosorption rate. Furthermore, a fixed-bed biosorption experiment shows that calcium alginate has a significant capacity for copper ion removal. The two-pK Basic Stem model successfully represents the surface charge and equilibrium biosorption experimental data. The calculation results demonstrate that the copper removal may result from the binding of free copper and its hydroxide with surface functional groups of the biosorbents.« less

Grouping in decomposition method for multi-item capacitated lot-sizing problem with immediate lost sales and joint and item-dependent setup cost

NASA Astrophysics Data System (ADS)

Narenji, M.; Fatemi Ghomi, S. M. T.; Nooraie, S. V. R.

2011-03-01

This article examines a dynamic and discrete multi-item capacitated lot-sizing problem in a completely deterministic production or procurement environment with limited production/procurement capacity where lost sales (the loss of customer demand) are permitted. There is no inventory space capacity and the production activity incurs a fixed charge linear cost function. Similarly, the inventory holding cost and the cost of lost demand are both associated with a linear no-fixed charge function. For the sake of simplicity, a unit of each item is assumed to consume one unit of production/procurement capacity. We analyse a different version of setup costs incurred by a production or procurement activity in a given period of the planning horizon. In this version, called the joint and item-dependent setup cost, an additional item-dependent setup cost is incurred separately for each produced or ordered item on top of the joint setup cost.

Primary Energy Reconstruction from the Charged Particle Densities Recorded with the KASCADE-Grande Detector at 500 m Distance from Shower Core

NASA Astrophysics Data System (ADS)

Toma, G.; Apel, W. D.; Arteaga, J. C.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Buchholz, P.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Finger, M.; Fuhrmann, D.; Ghia, P. L.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Kickelbick, D.; Klages, H. O.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Mayer, H. J.; Melissas, M.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Palmieri, N.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schröder, F.; Sima, O.; Trinchero, G. C.; Ulrich, H.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.

2010-11-01

Previous EAS investigations have shown that for a fixed primary energy the charged particle density becomes independent of the primary mass at certain (fixed) distances from the shower core. This feature can be used as an estimator for the primary energy. We present results on the reconstruction of the primary energy spectrum of cosmic rays from the experimentally recorded S(500) observable (the density of charged particles at 500 m distance to the shower core) using the KASCADE-Grande detector array. The KASCADE-Grande experiment is hosted by the Karlsruhe Institute for Technology-Campus North, Karlsruhe, Germany, and operated by an international collaboration. The constant intensity cut (CIC) method is applied to evaluate the attenuation of the S(500) observable with the zenith angle and is corrected for. A calibration of S(500) values with the primary energy has been worked out by simulations and was applied to the data to obtain the primary energy spectrum (in the energy range log10[E0/GeV]∈[7.5,9]). The systematic uncertainties induced by different sources are considered. In addition, a correction based on a response matrix is applied to account for the effects of shower-to-shower fluctuations on the spectral index of the reconstructed energy spectrum.

Thermodynamics Calculation and Experimental Study on Separation of Bismuth from a Bismuth Glance Concentrate Through a Low-Temperature Molten Salt Smelting Process

NASA Astrophysics Data System (ADS)

Yang, Jian-Guang; He, De-Wen; Tang, Chao-Bo; Chen, Yong-Ming; Sun, Ya-Hui; Tang, Mo-Tang

2011-08-01

The main purpose of this study is to characterize and separate bismuth from a bismuth glance concentrate through a low-temperature, sulfur-fixing smelting process. This article reports on a study conducted on the optimization of process parameters, such as Na2CO3 and zinc oxide wt pct in charging, smelting temperature, smelting duration on the bismuth yield, resultant crude bismuth grade, and sulfur-fixing rate. A maximum bismuth recovery of 97.31 pct, crude bismuth grade of 96.93 pct, and 98.23 pct sulfur-fixing rate are obtained when a charge (containing 63.50 wt pct of Na2CO3 and 22.50 wt pct of bismuth glance, as well as 5 pct in excess of the stoichiometric requirement of zinc oxide dosage) is smelted at 1000 K (727 °C) for 150 minutes. This smelting operation is free from atmospheric pollution because zinc oxide is used as the sulfur-fixing agent, which can capture sulfur from bismuth sulfide and form the more thermodynamic-stable compound, zinc sulfide. The solid residue is subjected to a mineral dressing operation to obtain suspension, which is filtered to produce a cake, representing the solid particles of zinc sulfide. Based on the results of the chemical content analysis of the as-resultant zinc sulfide, more than 93 pct zinc sulfide can be recovered, and the recovered zinc sulfide grade can reach 60.20 pct. This material can be sold as zinc sulfide concentrate or roasted to be regenerated as zinc oxide.

Plantaricin A, a cationic peptide produced by Lactobacillus plantarum, permeabilizes eukaryotic cell membranes by a mechanism dependent on negative surface charge linked to glycosylated membrane proteins.

PubMed

Sand, Sverre L; Nissen-Meyer, Jon; Sand, Olav; Haug, Trude M

2013-02-01

Lactobacillus plantarum C11 releases plantaricin A (PlnA), a cationic peptide pheromone that has a membrane-permeabilizing, antimicrobial effect. We have previously shown that PlnA may also permeabilize eukaryotic cells, with a potency that differs between cell types. It is generally assumed that cationic antimicrobial peptides exert their effects through electrostatic attraction to negatively charged phospholipids in the membrane. The aim of the present study was to investigate if removal of the negative charge linked to glycosylated proteins at the cell surface reduces the permeabilizing potency of PlnA. The effects of PlnA were tested on clonal rat anterior pituitary cells (GH(4) cells) using patch clamp and microfluorometric techniques. In physiological extracellular solution, GH(4) cells are highly sensitive to PlnA, but the sensitivity was dramatically reduced in solutions that partly neutralize the negative surface charge of the cells, in agreement with the notion that electrostatic interactions are probably important for the PlnA effects. Trypsination of cells prior to PlnA exposure also rendered the cells less sensitive to the peptide, suggesting that negative charges linked to membrane proteins are involved in the permeabilizing action. Finally, pre-exposure of cells to a mixture of enzymes that split carbohydrate residues from the backbone of glycosylated proteins also impeded the PlnA-induced membrane permeabilization. We conclude that electrostatic attraction between PlnA and glycosylated membrane proteins is probably an essential first step before PlnA can interact with membrane phospholipids. Deviating glycosylation patterns may contribute to the variation in PlnA sensitivity of different cell types, including cancerous cells and their normal counterparts. Copyright © 2012 Elsevier B.V. All rights reserved.

Method of making maximally dispersed heterogeneous catalysts

DOEpatents

Jennison, Dwight R [Albuquerque, NM

2005-11-15

A method of making a catalyst with monolayer or sub-monolayer metal by controlling the wetting characteristics on the support surface and increasing the adhesion between the catalytic metal and an oxide layer. There are two methods that have been demonstrated by experiment and supported by theory. In the first method, which is useful for noble metals as well as others, a negatively-charged species is introduced to the surface of a support in sub-ML coverage. The layer-by-layer growth of metal deposited onto the oxide surface is promoted because the adhesion strength of the metal-oxide interface is increased. This method can also be used to achieve nanoislands of metal upon sub-ML deposition. The negatively-charged species can either be deposited onto the oxide surface or a compound can be deposited that dissociates on, or reacts with, the surface to form the negatively-charged species. The deposited metal adatoms can thereby bond laterally to the negatively-charged species as well as vertically to the oxide surface. Thus the negatively-charged species serve as anchors for the metal. In the second method, a chemical reaction that occurs when most metals are deposited on a fully hydroxylated oxide surface is used to create cationic metal species that bind strongly both to the substrate and to metallic metal atoms. These are incorporated into the top layer of the substrate and bind strongly both to the substrate and to metallic metal atoms. In this case, these oxidized metal atoms serve as the anchors. Here, as in the previous method, nanoislands of catalytic metal can be achieved to increase catalytic activity, or monolayers or bilayers of reactive metal can also be made.

Peptide:lipid ratio and membrane surface charge determine the mechanism of action of the antimicrobial peptide BP100. Conformational and functional studies.

PubMed

Manzini, Mariana C; Perez, Katia R; Riske, Karin A; Bozelli, José C; Santos, Talita L; da Silva, Marcia A; Saraiva, Greice K V; Politi, Mario J; Valente, Ana P; Almeida, Fábio C L; Chaimovich, Hernan; Rodrigues, Magali A; Bemquerer, Marcelo P; Schreier, Shirley; Cuccovia, Iolanda M

2014-07-01

The cecropin-melittin hybrid antimicrobial peptide BP100 (H-KKLFKKILKYL-NH2) is selective for Gram-negative bacteria, negatively charged membranes, and weakly hemolytic. We studied BP100 conformational and functional properties upon interaction with large unilamellar vesicles, LUVs, and giant unilamellar vesicles, GUVs, containing variable proportions of phosphatidylcholine (PC) and negatively charged phosphatidylglycerol (PG). CD and NMR spectra showed that upon binding to PG-containing LUVs BP100 acquires α-helical conformation, the helix spanning residues 3-11. Theoretical analyses indicated that the helix is amphipathic and surface-seeking. CD and dynamic light scattering data evinced peptide and/or vesicle aggregation, modulated by peptide:lipid ratio and PG content. BP100 decreased the absolute value of the zeta potential (ζ) of LUVs with low PG contents; for higher PG, binding was analyzed as an ion-exchange process. At high salt, BP100-induced LUVS leakage requires higher peptide concentration, indicating that both electrostatic and hydrophobic interactions contribute to peptide binding. While a gradual release took place at low peptide:lipid ratios, instantaneous loss occurred at high ratios, suggesting vesicle disruption. Optical microscopy of GUVs confirmed BP100-promoted disruption of negatively charged membranes. The mechanism of action of BP100 is determined by both peptide:lipid ratio and negatively charged lipid content. While gradual release results from membrane perturbation by a small number of peptide molecules giving rise to changes in acyl chain packing, lipid clustering (leading to membrane defects), and/or membrane thinning, membrane disruption results from a sequence of events - large-scale peptide and lipid clustering, giving rise to peptide-lipid patches that eventually would leave the membrane in a carpet-like mechanism. Copyright © 2014 Elsevier B.V. All rights reserved.

A lower isoelectric point increases signal sequence-mediated secretion of recombinant proteins through a bacterial ABC transporter.

PubMed

Byun, Hyunjong; Park, Jiyeon; Kim, Sun Chang; Ahn, Jung Hoon

2017-12-01

Efficient protein production for industrial and academic purposes often involves engineering microorganisms to produce and secrete target proteins into the culture. Pseudomonas fluorescens has a TliDEF ATP-binding cassette transporter, a type I secretion system, which recognizes C-terminal LARD3 signal sequence of thermostable lipase TliA. Many proteins are secreted by TliDEF in vivo when recombined with LARD3, but there are still others that cannot be secreted by TliDEF even when LARD3 is attached. However, the factors that determine whether or not a recombinant protein can be secreted through TliDEF are still unknown. Here, we recombined LARD3 with several proteins and examined their secretion through TliDEF. We found that the proteins secreted via LARD3 are highly negatively charged with highly-acidic isoelectric points (pI) lower than 5.5. Attaching oligo-aspartate to lower the pI of negatively-charged recombinant proteins improved their secretion, and attaching oligo-arginine to negatively-charged proteins blocked their secretion by LARD3. In addition, negatively supercharged green fluorescent protein (GFP) showed improved secretion, whereas positively supercharged GFP did not secrete. These results disclosed that proteins' acidic pI and net negative charge are major factors that determine their secretion through TliDEF. Homology modeling for TliDEF revealed that TliD dimer forms evolutionarily-conserved positively-charged clusters in its pore and substrate entrance site, which also partially explains the pI dependence of the TliDEF-dependent secretions. In conclusion, lowering the isoelectric point improved LARD3-mediated protein secretion, both widening the range of protein targets for efficient production via secretion and signifying an important aspect of ABC transporter-mediated secretions. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Differential geometry based solvation model. III. Quantum formulation

PubMed Central

Chen, Zhan; Wei, Guo-Wei

2011-01-01

Solvation is of fundamental importance to biomolecular systems. Implicit solvent models, particularly those based on the Poisson-Boltzmann equation for electrostatic analysis, are established approaches for solvation analysis. However, ad hoc solvent-solute interfaces are commonly used in the implicit solvent theory. Recently, we have introduced differential geometry based solvation models which allow the solvent-solute interface to be determined by the variation of a total free energy functional. Atomic fixed partial charges (point charges) are used in our earlier models, which depends on existing molecular mechanical force field software packages for partial charge assignments. As most force field models are parameterized for a certain class of molecules or materials, the use of partial charges limits the accuracy and applicability of our earlier models. Moreover, fixed partial charges do not account for the charge rearrangement during the solvation process. The present work proposes a differential geometry based multiscale solvation model which makes use of the electron density computed directly from the quantum mechanical principle. To this end, we construct a new multiscale total energy functional which consists of not only polar and nonpolar solvation contributions, but also the electronic kinetic and potential energies. By using the Euler-Lagrange variation, we derive a system of three coupled governing equations, i.e., the generalized Poisson-Boltzmann equation for the electrostatic potential, the generalized Laplace-Beltrami equation for the solvent-solute boundary, and the Kohn-Sham equations for the electronic structure. We develop an iterative procedure to solve three coupled equations and to minimize the solvation free energy. The present multiscale model is numerically validated for its stability, consistency and accuracy, and is applied to a few sets of molecules, including a case which is difficult for existing solvation models. Comparison is made to many other classic and quantum models. By using experimental data, we show that the present quantum formulation of our differential geometry based multiscale solvation model improves the prediction of our earlier models, and outperforms some explicit solvation model. PMID:22112067

Concentration of poliovirus from tap water using positively charged microporous filters.

PubMed Central

Sobsey, M D; Jones, B L

1979-01-01

Microporous filters that are more electropositive than the negatively charged filters currently used for virus concentrations from water by filter adsorption-elution methods were evaluated for poliovirus recovery from tap water. Zeta Plus filters composed of diatomaceous earth-cellulose-"charge-modified" resin mixtures and having a net positive charge of up to pH 5 to 6 efficiently adsorbed poliovirus from tap water at ambient pH levels 7.0 to 7.5 without added multivalent cation salts. The adsorbed virus were eluted with glycine-NaOH, pH 9.5 to 11.5. Electropositive asbestos-cellulose filters efficiently adsorbed poliovirus from tap water without added multivalent cation salts between pH 3.5 and 9.0, and the absorbed viruses could be eluted with 3% beef extract, pH 9, but not with pH 9.5 to 11.5 glycine-NaOH. Under water quality conditions in which poliovirus recoveries from large volumes of water were less than 5% with conventional negatively charged filters and standard methods, recoveries with Zeta Plus filters averaged 64 and 22.5% for one- and two-stage concentration procedures, respectively. Electropositive filters appear to offer distinct advantages over conventional negatively charged filters for concentrating enteric viruses from water, and their behavior tends to confirm the importance of electrostatic forces in virus recovery from water by microporous filter adsorption-elution methods. PMID:36844

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

Wu, Chunya; Skelton, Adam A.; Chen, Mingjun

Here the binding of a negatively charged residue, aspartic acid (Asp) in tripeptide arginine-glycine-aspartic acid, onto a negatively charged hydroxylated rutile (110) surface in aqueous solution, containing divalent (Mg 2+, Ca 2+, or Sr 2+) or monovalent (Na +, K +, or Rb +) cations, was studied by molecular dynamics (MD) simulations. The results indicate that ionic radii and charges will significantly affect the hydration, adsorption geometry, and distance of cations from the rutile surface, thereby regulating the Asp/rutile binding mode. The adsorption strength of monovalent cations on the rutile surface in the order Na + > K + >more » Rb + shows a “reverse” lyotropic trend, while the divalent cations on the same surface exhibit a “regular” lyotropic behavior with decreasing crystallographic radii (the adsorption strength of divalent cations: Sr 2+ > Ca 2+ > Mg 2+). The Asp side chain in NaCl, KCl, and RbCl solutions remains stably H-bonded to the surface hydroxyls and the inner-sphere adsorbed compensating monovalent cations act as a bridge between the COO – group and the rutile, helping to “trap” the negatively charged Asp side chain on the negatively charged surface. In contrast, the mediating divalent cations actively participate in linking the COO– group to the rutile surface; thus the Asp side chain can remain stably on the rutile (110) surface, even if it is not involved in any hydrogen bonds with the surface hydroxyls. Inner- and outer-sphere geometries are all possible mediation modes for divalent cations in bridging the peptide to the rutile surface.« less

Stabilization of enzymes in ionic liquids via modification of enzyme charge.

PubMed

Nordwald, Erik M; Kaar, Joel L

2013-09-01

Due to the propensity of ionic liquids (ILs) to inactivate enzymes, the development of strategies to improve enzyme utility in these solvents is critical to fully exploit ILs for biocatalysis. We have developed a strategy to broadly improve enzyme utility in ILs based on elucidating the effect of charge modifications on the function of enzymes in IL environments. Results of stability studies in aqueous-IL mixtures indicated a clear connection between the ratio of enzyme-containing positive-to-negative sites and enzyme stability in ILs. Stability studies of the effect of [BMIM][Cl] and [EMIM][EtSO4 ] on chymotrypsin specifically found an optimum ratio of positively-charged amine-to-negatively-charged acid groups (0.39). At this ratio, the half-life of chymotrypsin was increased 1.6- and 4.3-fold relative to wild-type chymotrypsin in [BMIM][Cl] and [EMIM][EtSO4 ], respectively. The half-lives of lipase and papain were similarly increased as much as 4.0 and 2.4-fold, respectively, in [BMIM][Cl] by modifying the ratio of positive-to-negative sites of each enzyme. More generally, the results of stability studies found that modifications that reduce the ratio of enzyme-containing positive-to-negative sites improve enzyme stability in ILs. Understanding the impact of charge modification on enzyme stability in ILs may ultimately be exploited to rationally engineer enzymes for improved function in IL environments. Copyright © 2013 Wiley Periodicals, Inc.

Constrained Surface Complexation Modeling: Rutile in RbCl, NaCl, and NaCF 3SO 3 Media to 250 °C

DOE PAGES

Machesky, Michael L.; Předota, Milan; Ridley, Moira K.; ...

2015-06-01

In this paper, a comprehensive set of molecular-level results, primarily from classical molecular dynamics (CMD) simulations, are used to constrain CD-MUSIC surface complexation model (SCM) parameters describing rutile powder titrations conducted in RbCl, NaCl, and NaTr (Tr = triflate, CF 3SO 3 –) electrolyte media from 25 to 250 °C. Rb + primarily occupies the innermost tetradentate binding site on the rutile (110) surface at all temperatures (25, 150, 250 °C) and negative charge conditions (-0.1 and -0.2 C/m 2) probed via CMD simulations, reflecting the small hydration energy of this large, monovalent cation. Consequently, variable SCM parameters (Stern-layer capacitancemore » values and intrinsic Rb + binding constants) were adjusted relatively easily to satisfactorily match the CMD and titration data. The larger hydration energy of Na + results in a more complex inner-sphere distribution, which shifts from bidentate to tetradentate binding with increasing negative charge and temperature, and this distribution was not matched well for both negative charge conditions, which may reflect limitations in the CMD and/or SCM approaches. Finally, in particular, the CMD axial density profiles for Rb + and Na + reveal that peak binding distances shift toward the surface with increasing negative charge, suggesting that the CD-MUSIC framework may be improved by incorporating CD or Stern-layer capacitance values that vary with charge.« less

Constrained Surface Complexation Modeling: Rutile in RbCl, NaCl, and NaCF 3SO 3 Media to 250 °C

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

Machesky, Michael L.; Předota, Milan; Ridley, Moira K.

In this paper, a comprehensive set of molecular-level results, primarily from classical molecular dynamics (CMD) simulations, are used to constrain CD-MUSIC surface complexation model (SCM) parameters describing rutile powder titrations conducted in RbCl, NaCl, and NaTr (Tr = triflate, CF 3SO 3 –) electrolyte media from 25 to 250 °C. Rb + primarily occupies the innermost tetradentate binding site on the rutile (110) surface at all temperatures (25, 150, 250 °C) and negative charge conditions (-0.1 and -0.2 C/m 2) probed via CMD simulations, reflecting the small hydration energy of this large, monovalent cation. Consequently, variable SCM parameters (Stern-layer capacitancemore » values and intrinsic Rb + binding constants) were adjusted relatively easily to satisfactorily match the CMD and titration data. The larger hydration energy of Na + results in a more complex inner-sphere distribution, which shifts from bidentate to tetradentate binding with increasing negative charge and temperature, and this distribution was not matched well for both negative charge conditions, which may reflect limitations in the CMD and/or SCM approaches. Finally, in particular, the CMD axial density profiles for Rb + and Na + reveal that peak binding distances shift toward the surface with increasing negative charge, suggesting that the CD-MUSIC framework may be improved by incorporating CD or Stern-layer capacitance values that vary with charge.« less

Effective cytoplasmic release of siRNA from liposomal carriers by controlling the electrostatic interaction of siRNA with a charge-invertible peptide, in response to cytoplasmic pH

NASA Astrophysics Data System (ADS)

Itakura, Shoko; Hama, Susumu; Matsui, Ryo; Kogure, Kentaro

2016-05-01

Condensing siRNA with cationic polymers is a major strategy used in the development of siRNA carriers that can avoid degradation by nucleases and achieve effective delivery of siRNA into the cytoplasm. However, ineffective release of siRNA from such condensed forms into the cytoplasm is a limiting step for induction of RNAi effects, and can be attributed to tight condensation of siRNA with the cationic polymers, due to potent electrostatic interactions. Here, we report that siRNA condensed with a slightly acidic pH-sensitive peptide (SAPSP), whose total charge is inverted from positive to negative in response to cytoplasmic pH, is effectively released via electrostatic repulsion of siRNA with negatively charged SAPSP at cytoplasmic pH (7.4). The condensed complex of siRNA and positively-charged SAPSP at acidic pH (siRNA/SAPSP) was found to result in almost complete release of siRNA upon charge inversion of SAPSP at pH 7.4, with the resultant negatively-charged SAPSP having no undesirable interactions with endogenous mRNA. Moreover, liposomes encapsulating siRNA/SAPSP demonstrated knockdown efficiencies comparable to those of commercially available siRNA carriers. Taken together, SAPSP may be very useful as a siRNA condenser, as it facilitates effective cytoplasmic release of siRNA, and subsequent induction of specific RNAi effects.Condensing siRNA with cationic polymers is a major strategy used in the development of siRNA carriers that can avoid degradation by nucleases and achieve effective delivery of siRNA into the cytoplasm. However, ineffective release of siRNA from such condensed forms into the cytoplasm is a limiting step for induction of RNAi effects, and can be attributed to tight condensation of siRNA with the cationic polymers, due to potent electrostatic interactions. Here, we report that siRNA condensed with a slightly acidic pH-sensitive peptide (SAPSP), whose total charge is inverted from positive to negative in response to cytoplasmic pH, is effectively released via electrostatic repulsion of siRNA with negatively charged SAPSP at cytoplasmic pH (7.4). The condensed complex of siRNA and positively-charged SAPSP at acidic pH (siRNA/SAPSP) was found to result in almost complete release of siRNA upon charge inversion of SAPSP at pH 7.4, with the resultant negatively-charged SAPSP having no undesirable interactions with endogenous mRNA. Moreover, liposomes encapsulating siRNA/SAPSP demonstrated knockdown efficiencies comparable to those of commercially available siRNA carriers. Taken together, SAPSP may be very useful as a siRNA condenser, as it facilitates effective cytoplasmic release of siRNA, and subsequent induction of specific RNAi effects. Electronic supplementary information (ESI) available: De-condensation of siRNA cores by addition of heparin; time-lapse moving image of the siRNA release. See DOI: 10.1039/c5nr08365f

First results of the Colombia Lightning Mapping Array

NASA Astrophysics Data System (ADS)

López, Jesus; Montanyà, Joan; van der Velde, Oscar; Romero, David; Fabró, Ferran; Taborda, John; Aranguren, Daniel; Torres, Horacio

2016-04-01

In April 2015 the 3D Lightning Mapping Array (COLMA) network was installed on Santa Marta area (north of Colombia). The COLMA maps VHF radio emissions of lightning leaders in three dimensions by the time-of-arrival technique (Rison et al., 1999). This array has six sensors with base lines between 5 km to 20 km. The COLMA is the first VHF 3D network operating in the tropics and it has been installed in the frame of ASIM (Atmosphere-Space Interactions Monitor) ESA's mission in order to investigate the electrical characteristics of tropical thunderstorms favorable for the production of Terrestrial Gamma ray Flashes (TGF). In this paper we present COLMA data of several storms. We discuss lightning activity, lightning leader altitudes and thunderstorm charge structures compared to data form our ELMA (Ebro Lightning Mapping Array) at the north-east coast of Spain. The data confirm what we expected, lightning leaders can propagate at higher altitudes compared to mid latitude thunderstorms because the higher vertical development of tropical thunderstorms. A simple inspection of a ten minute period of the 16th of November of 2015 storm shows a tripolar electric charge structure. In that case, the midlevel negative charge region was located between 7 to 9 km. The structure presented a lower positive charge below the midlevel negative and centred at 6.5 km and an upper positive charge region extending from 9 km to slightly more than 15 km. This vertical extension of the upper positive charge where negative leaders evolve is significantly larger compared to the storms at the ELMA area in Spain. COLMA has shown frequent activity of negative leaders reaching altitudes of more than 15 km.

Urinary Alpha-1-Acid Glycoprotein Is a Sensitive Marker of Glomerular Protein Leakage at Altitude.

PubMed

Talks, Ben J; Bradwell, Susie B; Delamere, John; Rayner, Will; Clarke, Alex; Lewis, Chris T; Thomas, Owen D; Bradwell, Arthur R

2018-06-11

Talks, Ben J., Susie B. Bradwell, John Delamere, Will Rayner, Alex Clarke, Chris T. Lewis, Owen D. Thomas, and Arthur R. Bradwell. Urinary alpha-1-acid glycoprotein is a sensitive marker of glomerular protein leakage at altitude. High Alt Med Biol 00:000-000, 2018. Proteinuria is an established feature of ascent to altitude and may be caused by a loss of negative charges on glomerular capillary walls (GCWs). To test this hypothesis, we measured two similar sized but oppositely charged proteins in urine: negatively charged alpha-1-acid glycoprotein (α1-AGP, 41-43 kDa) and positively charged dimeric lambda free light chains (λ-FLCs, 50 kDa). Twenty-four-hour urinary leakage was compared with albumin, a 66 kDa negatively charged protein. We studied 23 individuals (ages 23-78 years, male = 17) at baseline (140 m) and daily during an expedition to 5035 m. The results showed a significant increase in median urinary leakage of α1-AGP (p < 0.0001; 6.85-fold) and albumin (p = 0.0006; 1.65-fold) with ascent to altitude, but no significant increase in leakage of λ-FLCs (p = 0.39; 1.14-fold). α1-AGP correlated with the daily ascent profile (p = 0.0026) and partial pressure of oxygen (p = 0.01), whereas albumin showed no correlation (p = 0.19). Urinary α1-AGP was a more sensitive marker of altitude proteinuria than urinary albumin and λ-FLCs, and supported the possibility of loss of GCW negative charges at altitude.

A managerial approach to costing fixed assets in health care organizations: the role of depreciation and interest.

PubMed

Goldschmidt, Y; Gafni, A

1991-01-01

The economic aspect of depreciation and interest on capital are incorporated within a managerial accounting framework by treating both items as imputed charges to be debited to the users of the assets' services. The costs of these services is examined for individual assets that provide either uniform or declining service over the expected life, and for a stock of assets where the character of the individual assets is ignored. By using imputed charges, the hospital's net income is allocated to its sources.

Cosmological constant and quantum gravitational corrections to the running fine structure constant.

PubMed

Toms, David J

2008-09-26

The quantum gravitational contribution to the renormalization group behavior of the electric charge in Einstein-Maxwell theory with a cosmological constant is considered. Quantum gravity is shown to lead to a contribution to the running charge not present when the cosmological constant vanishes. This reopens the possibility, suggested by Robinson and Wilczek, of altering the scaling behavior of gauge theories at high energies although our result differs. We show the possibility of an ultraviolet fixed point that is linked directly to the cosmological constant.

Magnetic properties of confined holographic QCD

NASA Astrophysics Data System (ADS)

Bergman, Oren; Lifschytz, Gilad; Lippert, Matthew

2013-12-01

We investigate the Sakai-Sugimoto model at nonzero baryon chemical potential in a background magnetic field in the confined phase where chiral symmetry is broken. The D8-brane Chern-Simons term holographically encodes the axial anomaly and generates a gradient of the η' meson, which carries a non-vanishing baryon charge. Above a critical value of the chemical potential, there is a second-order phase transition to a mixed phase which includes also ordinary baryonic matter. However, at fixed baryon charge density, the matter is purely η'-gradient above a critical magnetic field.

Particle size, charge and colloidal stability of humic acids coprecipitated with Ferrihydrite.

PubMed

Angelico, Ruggero; Ceglie, Andrea; He, Ji-Zheng; Liu, Yu-Rong; Palumbo, Giuseppe; Colombo, Claudio

2014-03-01

Humic acids (HA) have a colloidal character whose size and negative charge are strictly dependent on surface functional groups. They are able to complex large amount of poorly ordered iron (hydr)oxides in soil as a function of pH and other environmental conditions. Accordingly, with the present study we intend to assess the colloidal properties of Fe(II) coprecipitated with humic acids (HA) and their effect on Fe hydroxide crystallinity under abiotic oxidation and order of addition of both Fe(II) and HA. TEM, XRD and DRS experiments showed that Fe-HA consisted of Ferrihydrite with important structural variations. DLS data of Fe-HA at acidic pH showed a bimodal size distribution, while at very low pH a slow aggregation process was observed. Electrophoretic zeta-potential measurements revealed a negative surface charge for Fe-HA macromolecules, providing a strong electrostatic barrier against aggregation. Under alkaline conditions HA chains swelled, which resulted in an enhanced stabilization of the colloid particles. The increasing of zeta potential and size of the Fe-HA macromolecules, reflects a linear dependence of both with pH. The increase in the size and negative charge of the Fe-HA precipitate seems to be more affected by the ionization of the phenolic acid groups, than by the carboxylic acid groups. The main cause of negative charge generation of Fe/HA is due to increased dissociation of phenolic groups in more expanded structure. The increased net negative surface potential induced by coprecipitation with Ferrihydrite and the correspondent changes in configuration of the HA could trigger the inter-particle aggregation with the formation of new negative surface. The Fe-HA coprecipitation can reduce electrosteric repulsive forces, which in turn may inhibit the aggregation process at different pH. Therefore, coprecipitation of Ferrihydrite would be expected to play an important role in the carbon stabilization and persistence not only in organic soils, but also in waters containing dissolved organic matter. Copyright © 2013 Elsevier Ltd. All rights reserved.

Describing long-range charge-separation processes with subsystem density-functional theory

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

Solovyeva, Alisa; Neugebauer, Johannes, E-mail: j.neugebauer@uni-muenster.de; Pavanello, Michele, E-mail: m.pavanello@rutgers.edu

2014-04-28

Long-range charge-transfer processes in extended systems are difficult to describe with quantum chemical methods. In particular, cost-effective (non-hybrid) approximations within time-dependent density functional theory (DFT) are not applicable unless special precautions are taken. Here, we show that the efficient subsystem DFT can be employed as a constrained DFT variant to describe the energetics of long-range charge-separation processes. A formal analysis of the energy components in subsystem DFT for such excitation energies is presented, which demonstrates that both the distance dependence and the long-range limit are correctly described. In addition, electronic couplings for these processes as needed for rate constants inmore » Marcus theory can be obtained from this method. It is shown that the electronic structure of charge-separated states constructed by a positively charged subsystem interacting with a negatively charged one is difficult to converge — charge leaking from the negative subsystem to the positive one can occur. This problem is related to the delocalization error in DFT and can be overcome with asymptotically correct exchange–correlation (XC) potentials or XC potentials including a sufficiently large amount of exact exchange. We also outline an approximate way to obtain charge-transfer couplings between locally excited and charge-separated states.« less

Magnetoactive Acoustic Metamaterials.

PubMed

Yu, Kunhao; Fang, Nicholas X; Huang, Guoliang; Wang, Qiming

2018-04-11

Acoustic metamaterials with negative constitutive parameters (modulus and/or mass density) have shown great potential in diverse applications ranging from sonic cloaking, abnormal refraction and superlensing, to noise canceling. In conventional acoustic metamaterials, the negative constitutive parameters are engineered via tailored structures with fixed geometries; therefore, the relationships between constitutive parameters and acoustic frequencies are typically fixed to form a 2D phase space once the structures are fabricated. Here, by means of a model system of magnetoactive lattice structures, stimuli-responsive acoustic metamaterials are demonstrated to be able to extend the 2D phase space to 3D through rapidly and repeatedly switching signs of constitutive parameters with remote magnetic fields. It is shown for the first time that effective modulus can be reversibly switched between positive and negative within controlled frequency regimes through lattice buckling modulated by theoretically predicted magnetic fields. The magnetically triggered negative-modulus and cavity-induced negative density are integrated to achieve flexible switching between single-negative and double-negative. This strategy opens promising avenues for remote, rapid, and reversible modulation of acoustic transportation, refraction, imaging, and focusing in subwavelength regimes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Trajectories of Moving Charges in Static Electric Fields.

ERIC Educational Resources Information Center

Kirkup, L.

1986-01-01

Describes the implementation of a trajectory-plotting program for a microcomputer; shows how it may be used to demonstrate the focusing effect of a simple electrostatic lens. The computer program is listed and diagrams are included that show comparisons of trajectories of negative charges in the vicinity of positive charges. (TW)

Integration Assessment of Visiting Vehicle Induced Electrical Charging of the International Space Station Structure

NASA Technical Reports Server (NTRS)

Kramer, Leonard; Kerslake, Thomas W.; Galofaro, Joel T.

2010-01-01

The International Space Station (ISS) undergoes electrical charging in low Earth orbit (LEO) due to positively biased, exposed conductors on solar arrays that collect electrical charges from the space plasma. Exposed solar array conductors predominately collect negatively charged electrons and thus drive the metal ISS structure electrical ground to a negative floating potential (FP) relative to plasma. This FP is variable in location and time as a result of local ionospheric conditions. ISS motion through Earth s magnetic field creates an addition inductive voltage up to 20 positive and negative volts across ISS structure depending on its attitude and location in orbit. ISS Visiting Vehicles (VVs), such as the planned Orion crew exploration vehicle, contribute to the ISS plasma charging processes. Upon physical contact with ISS, the current collection properties of VVs combine with ISS. This is an ISS integration concern as FP must be controlled to minimize arcing of ISS surfaces and ensure proper management of extra vehicular activity crewman shock hazards. This report is an assessment of ISS induced charging from docked Orion vehicles employing negatively grounded, 130 volt class, UltraFlex (ATK Space Systems) solar arrays. To assess plasma electron current collection characteristics, Orion solar cell test coupons were constructed and subjected to plasma chamber current collection measurements. During these tests, coupon solar cells were biased between 0 and 120 V while immersed in a simulated LEO plasma. Tests were performed using several different simulated LEO plasma densities and temperatures. These data and associated theoretical scaling of plasma properties, were combined in a numerical model which was integrated into the Boeing Plasma Interaction Model. It was found that the solar array design for Orion will not affect the ISS FP by more than about 2 V during worst case charging conditions. This assessment also motivated a trade study to determine acceptable plasma electron current levels that can be collected by a single or combined fleet of ISS-docked VVs.

Kinetics and thermodynamics of chlorpromazine interaction with lipid bilayers: effect of charge and cholesterol.

PubMed

Martins, Patrícia T; Velazquez-Campoy, Adrian; Vaz, Winchil L C; Cardoso, Renato M S; Valério, Joana; Moreno, Maria João

2012-03-07

Passive transport across cell membranes is the major route for the permeation of xenobiotics through tight endothelia such as the blood–brain barrier. The rate of passive permeation through lipid bilayers for a given drug is therefore a critical step in the prediction of its pharmacodynamics. We describe a detailed study on the kinetics and thermodynamics for the interaction of chlorpromazine (CPZ), an antipsychotic drug used in the treatment of schizophrenia, with neutral and negatively charged lipid bilayers. Isothermal titration calorimetry was used to study the partition and translocation of CPZ in lipid membranes composed of pure POPC, POPC:POPS (9:1), and POPC:Chol:POPS (6:3:1). The membrane charge due to the presence of POPS as well as the additional charge resulting from the introduction of CPZ in the membrane were taken into account, allowing the calculation of the intrinsic partition coefficients (K(P)) and the enthalpy change (ΔH) associated with the process. The enthalpy change upon partition to all lipid bilayers studied is negative, but a significant entropy contribution was also observed for partition to the neutral membrane. Because of the positive charge of CPZ, the presence of negatively charged lipids in the bilayer increases both the observed amount of CPZ that partitions to the membrane (KP(obs)) and the magnitude of ΔH. However, when the electrostatic effects are discounted, the intrinsic partition coefficient was smaller, indicating that the hydrophobic contribution was less significant for the negatively charged membrane. The presence of cholesterol strongly decreases the affinity of CPZ for the bilayer in terms of both the amount of CPZ that associates with the membrane and the interaction enthalpy. A quantitative characterization of the rate of CPZ translocation through membranes composed of pure POPC and POPC:POPS (9:1) was also performed using an innovative methodology developed in this work based on the kinetics of the heat evolved due to the interaction of CPZ with the membranes. © 2012 American Chemical Society

Statistical and Financial Information of Kansas Community Junior Colleges.

ERIC Educational Resources Information Center

Kansas State Dept. of Education, Topeka.

Data tables outline statistical and financial information for the 19 Kansas community junior colleges. Eight sections concern the following: (1) 1977-78 actual general fund expenditures in areas of administration, instruction, student services, health, transportation, plant operation and maintenance, fixed charges, food services, student body…

46 CFR 108.495 - Spare charges.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., offices, lockers, small storerooms, and pantries, open decks, and similar spaces None required. service... extinguishing system is installed. 2. Not required where a fixed foam system is installed in accordance with § 108.489 of this subpart. Table 108.495(b) Classification: Type and size Water liters (gallons) Foam...

46 CFR 108.495 - Spare charges.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., offices, lockers, small storerooms, and pantries, open decks, and similar spaces None required. service... extinguishing system is installed. 2. Not required where a fixed foam system is installed in accordance with § 108.489 of this subpart. Table 108.495(b) Classification: Type and size Water liters (gallons) Foam...

46 CFR 108.495 - Spare charges.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., offices, lockers, small storerooms, and pantries, open decks, and similar spaces None required. service... extinguishing system is installed. 2. Not required where a fixed foam system is installed in accordance with § 108.489 of this subpart. Table 108.495(b) Classification: Type and size Water liters (gallons) Foam...

46 CFR 108.495 - Spare charges.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., offices, lockers, small storerooms, and pantries, open decks, and similar spaces None required. service... extinguishing system is installed. 2. Not required where a fixed foam system is installed in accordance with § 108.489 of this subpart. Table 108.495(b) Classification: Type and size Water liters (gallons) Foam...

46 CFR 108.495 - Spare charges.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., offices, lockers, small storerooms, and pantries, open decks, and similar spaces None required. service... extinguishing system is installed. 2. Not required where a fixed foam system is installed in accordance with § 108.489 of this subpart. Table 108.495(b) Classification: Type and size Water liters (gallons) Foam...

Red blood cells aligning inside innovative liquid crystal cell

NASA Astrophysics Data System (ADS)

Likhomanova, S. V.; Kamanin, A. A.; Kamanina, N. V.

2017-11-01

Investigation results of red blood cells (human erythrocytes) aligning and fixing inside the liquid crystal (LC) cell have been presented in the present paper. LC cells have been modified through the improved nanostructured relief and LC sensitized with intermolecular charge transfer complex COANP-C70.

76 FR 28121 - Notice of Passenger Facility Charge (PFC) Approvals and Disapprovals

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-13

.... Security cameras. Snow removal equipment. Update airport master plan study phases I and II. Obstruction... general aviation area. Preconditioned air and fixed ground power. Airfield environmental assessment... Withdrawal: April 19, 2011. Decision Date: April 25, 2011. FOR FURTHER INFORMATION CONTACT: Anna Guss...

Production of negatively charged radioactive ion beams

DOE PAGES

Liu, Y.; Stracener, D. W.; Stora, T.

2017-02-15

Beams of short-lived radioactive nuclei are needed for frontier experimental research in nuclear structure, reactions, and astrophysics. Negatively charged radioactive ion beams have unique advantages and allow for the use of a tandem accelerator for post-acceleration, which can provide the highest beam quality and continuously variable energies. Negative ion beams can be obtained with high intensity and some unique beam purification techniques based on differences in electronegativity and chemical reactivity can be used to provide beams with high purity. This article describes the production of negative radioactive ion beams at the former holifield radioactive ion beam facility at Oak Ridgemore » National Laboratory and at the CERN ISOLDE facility with emphasis on the development of the negative ion sources employed at these two facilities.« less

Effect of Ca2+ ion concentration on adsorption of poly(carboxylate ether)-based (PCE) superplasticizer on mica.

PubMed

Wu, Bo; Chun, Byong-Wa; Gu, Le; Kuhl, Tonya L

2018-05-09

Poly(carboxylate ether)-based (PCE) superplasticizers consist of a carboxylic acid backbone and grafted poly(ethylene glycol) (PEG) side chains. Ca 2+ ion bridging mechanism is commonly purported to control PCE's adsorption on negatively charged cement particle surfaces in cement suspension, thus PCE was expected to adsorb on negatively charged surfaces in synthetic pore solutions via Ca 2+ /COO - interactions. Adsorption behaviors of a commercial PCE on negatively charged mica were studied in aqueous electrolyte solutions by a surface forces apparatus. Direct force measurements indicated that the PCE adsorbed onto mica from 0.1 M K 2 SO 4 due to K + ion chelation by the ether oxygen units CH 2 CH 2 O on the PEG chains, but surprisingly did not adsorb from either 0.1 M K 2 SO 4 with saturated Ca(OH) 2 or 0.1 M Ca(NO 3 ) 2 . The adsorption in K 2 SO 4 was weak, enabling the adsorbed PCE layers to be squeezed out under modest compression. Upon separating the surfaces, the PCE immediately achieved an identical re-adsorption. In high-calcium conditions, the PCE was highly positively charged due to Ca 2+ ion chelation by PEG chains and backbone carboxylic groups COO - , and mica also underwent charge reversal due to electrostatic adsorption/binding of Ca 2+ ions. Consequently, the interaction between mica and PCE was electrostatically repulsive and no PCE adsorption occurred. These findings can be explained by the complex interplay of ion chelation by PEG chains, electrostatic binding and screening interactions with charged surfaces in the presence of monovalent and divalent counterions, and ultimately charge reversal of both the charged surfaces and polyelectrolyte in high divalent ion conditions. Copyright © 2018 Elsevier Inc. All rights reserved.

Ion counting in supercapacitor electrodes using NMR spectroscopy.

PubMed

Griffin, John M; Forse, Alexander C; Wang, Hao; Trease, Nicole M; Taberna, Pierre-Louis; Simon, Patrice; Grey, Clare P

2014-01-01

(19)F NMR spectroscopy has been used to study the local environments of anions in supercapacitor electrodes and to quantify changes in the populations of adsorbed species during charging. In the absence of an applied potential, anionic species adsorbed within carbon micropores (in-pore) are distinguished from those in large mesopores and spaces between particles (ex-pore) by a characteristic nucleus-independent chemical shift (NICS). Adsorption experiments and two-dimensional exchange experiments confirm that anions are in dynamic equilibrium between the in- and ex-pore environments with an exchange rate in the order of tens of Hz. (19)F in situ NMR spectra recorded at different charge states reveal changes in the intensity and NICS of the in-pore resonances, which are interpreted in term of changes in the population and local environments of the adsorbed anions that arise due to the charge-storage process. A comparison of the results obtained for a range of electrolytes reveals that several factors influence the charging mechanism. For a tetraethylammonium tetrafluoroborate electrolyte, positive polarisation of the electrode is found to proceed by anion adsorption at a low concentration, whereas increased ion exchange plays a more important role for a high concentration electrolyte. In contrast, negative polarization of the electrode proceeds by cation adsorption for both concentrations. For a tetrabutylammonium tetrafluoroborate electrolyte, anion expulsion is observed in the negative charging regime; this is attributed to the reduced mobility and/or access of the larger cations inside the pores, which forces the expulsion of anions in order to build up ionic charge. Significant anion expulsion is also observed in the negative charging regime for alkali metal bis(trifluoromethane)sulfonimide electrolytes, suggesting that more subtle factors also affect the charging mechanism.

Enhanced performance of Zn(II)-doped lead-acid batteries with electrochemical active carbon in negative mass

NASA Astrophysics Data System (ADS)

Xiang, Jiayuan; Hu, Chen; Chen, Liying; Zhang, Dong; Ding, Ping; Chen, Dong; Liu, Hao; Chen, Jian; Wu, Xianzhang; Lai, Xiaokang

2016-10-01

The effect and mechanism of Zn(II) on improving the performances of lead-acid cell with electrochemical active carbon (EAC) in negative mass is investigated. The hydrogen evolution of the cell is significantly reduced due to the deposition of Zn on carbon surface and the increased porosity of negative mass. Zn(II) additives can also improve the low-temperature and high-rate capacities of the cell with EAC in negative mass, which ascribes to the formation of Zn on lead and carbon surface that constructs a conductive bridge among the active mass. Under the co-contribution of EAC and Zn(II), the partial-state-of-charge cycle life is greatly prolonged. EAC optimizes the NAM structure and porosity to enhance the charge acceptance and retard the lead sulfate accumulation. Zn(II) additive reduces the hydrogen evolution during charge process and improves the electric conductivity of the negative electrode. The cell with 0.6 wt% EAC and 0.006 wt% ZnO in negative mass exhibits 90% reversible capacity of the initial capacity after 2100 cycles. In contrast, the cell with 0.6 wt% EAC exhibits 84% reversible capacity after 2100 cycles and the control cell with no EAC and Zn(II) exhibits less than 80% reversible capacity after 1350 cycles.

Measurements of Lunar Dust Charging Properties by Electron Impact

NASA Technical Reports Server (NTRS)

Abbas, Mian M.; Tankosic, Dragana; Craven, Paul D.; Schneider, Todd A.; Vaughn, Jason A.; LeClair, Andre; Spann, James F.; Norwood, Joseph K.

2009-01-01

Dust grains in the lunar environment are believed to be electrostatically charged predominantly by photoelectric emissions resulting from solar UV radiation on the dayside, and on the nightside by interaction with electrons in the solar wind plasma. In the high vacuum environment on the lunar surface with virtually no atmosphere, the positive and negative charge states of micron/submicron dust grains lead to some unusual physical and dynamical dust phenomena. Knowledge of the electrostatic charging properties of dust grains in the lunar environment is required for addressing their hazardous effect on the humans and mechanical systems. It is well recognized that the charging properties of individual small micron size dust grains are substantially different from the measurements on bulk materials. In this paper we present the results of measurements on charging of individual Apollo 11 and Apollo 17 dust grains by exposing them to mono-energetic electron beams in the 10-100 eV energy range. The charging/discharging rates of positively and negatively charged particles of approx. 0.1 to 5 micron radii are discussed in terms of the sticking efficiencies and secondary electron yields. The secondary electron emission process is found to be a complex and effective charging/discharging mechanism for incident electron energies as low as 10-25 eV, with a strong dependence on particle size. Implications of the laboratory measurements on the nature of dust grain charging in the lunar environment are discussed.

Advances in Charge-Compensation in Secondary Ion Mass Spectrometry (SIMS)

NASA Astrophysics Data System (ADS)

Hervig, R. L.; Chen, J.; Schauer, S.; Stanley, B. D.; Moore, G. M.; Roggensack, K.

2012-12-01

In secondary ion mass spectrometry (SIMS), a sample is bombarded by a charged particle beam (the primary ion) and sputtered positive or negative secondary ions are analyzed in a mass spectrometer. When the target is not conducting (like many geological materials), sample charging can result in variable deflection of secondary ions away from the mass spectrometer and a low, unstable, or absent signal. Applying a thin conducting coat (e.g., C, Au) to polished samples is required, and if the primary ion beam is negatively-charged, the build-up of negative charge can be alleviated by secondary electrons draining to the conducting coat at the edge of the crater (if a positive potential is applied to the sample for the collection of positive secondary ions) or accelerated away from the crater (if a negative potential is applied for negative ion study). Unless the sputtered crater in the conducting coat becomes too large, sample charging can be kept at a controllable level, and high-quality trace element analyses and isotope ratios have been obtained using this technique over the past 3+ decades. When a positive primary beam is used, the resulting build-up of positive charge in the sample requires an electron gun to deliver sufficient negative charge to the sputtered crater. While there are many examples of successful analyses using this approach, the purpose of this presentation is to describe a very simple technique for aligning the electron gun on Cameca nf and 1270/80 SIMS instruments. This method allows reproducible analyses of insulating phases with a Cs+ primary beam and detection of negative secondary ions. Normally, the filament voltage on the E-gun is the same as the sample voltage; thus electrons do not strike the sample except when a positive charge has built up (e.g., in the analysis crater!). In this method, we decrease the sample voltage by 3 or more kV, so that the impact energy of the electrons is sufficient to induce a cathodoluminescent (CL) image on an appropriate sample (e.g., GaN). The CL image is made circular and homogeneous by adjusting the deflectors and a lens in the electron steering assembly, and the sample voltage is subsequently returned to the same value as the filament. Very minor corrections of the electron tuning (mostly by an external magnet known as Bx or B1) will then produce a uniform secondary ion image on a test insulator (a gold-coated glass slide) under Cs bombardment. The uniform electron density is correlated with reproducible calibration for hydrogen and carbon concentrations over a multi-day session and from session to session over a period of months. Outside visitors to the lab can use this set-up and obtain high-quality analyses with little to no previous training. Obtaining a homogeneous distribution of electrons over a maximum diameter (100+ microns) also reduces problems associated with changes in the position of the electron beam induced by stray magnetic fields. As a result, analyses of hydrogen isotopes and/or multi-element analysis routines using elemental H species are simplified.

Charged hadrons in local finite-volume QED+QCD with C⋆ boundary conditions

NASA Astrophysics Data System (ADS)

Lucini, B.; Patella, A.; Ramos, A.; Tantalo, N.

2016-02-01

In order to calculate QED corrections to hadronic physical quantities by means of lattice simulations, a coherent description of electrically-charged states in finite volume is needed. In the usual periodic setup, Gauss's law and large gauge transformations forbid the propagation of electrically-charged states. A possible solution to this problem, which does not violate the axioms of local quantum field theory, has been proposed by Wiese and Polley, and is based on the use of C⋆ boundary conditions. We present a thorough analysis of the properties and symmetries of QED in isolation and QED coupled to QCD, with C⋆ boundary conditions. In particular we learn that a certain class of electrically-charged states can be constructed in a fully consistent fashion without relying on gauge fixing and without peculiar complications. This class includes single particle states of most stable hadrons. We also calculate finite-volume corrections to the mass of stable charged particles and show that these are much smaller than in non-local formulations of QED.

High negative charge of a dust particle in a hot cathode discharge.

PubMed

Arnas, C; Mikikian, M; Doveil, F

1999-12-01

Dust particle levitation experiments in a plasma produced by a hot filament discharge, operating at low argon pressure, are presented. The basic characteristics of a dust grain trapped in a plate sheath edge in these experimental conditions are reported. Taking into account the sheath potential profiles measured with a differential emissive probe diagnostic, the forces applied to an isolated dust grain can be determined. Two different experimental methods yield approximately the same value for the dust charge. The observed high negative charge is mainly due to the contribution of the primary electrons emitted by the filaments as predicted by a simple model.

Optical pumping of electron and nuclear spin in a negatively-charged quantum dot

NASA Astrophysics Data System (ADS)

Bracker, Allan; Gershoni, David; Korenev, Vladimir

2005-03-01

We report optical pumping of electron and nuclear spins in an individual negatively-charged quantum dot. With a bias-controlled heterostructure, we inject one electron into the quantum dot. Intense laser excitation produces negative photoluminescence polarization, which is easily erased by the Hanle effect, demonstrating optical pumping of a long-lived resident electron. The electron spin lifetime is consistent with the influence of nuclear spin fluctuations. Measuring the Overhauser effect in high magnetic fields, we observe a high degree of nuclear spin polarization, which is closely correlated to electron spin pumping.

Induced-charge electroosmotic trapping of particles.

PubMed

Ren, Yukun; Liu, Weiyu; Jia, Yankai; Tao, Ye; Shao, Jinyou; Ding, Yucheng; Jiang, Hongyuan

2015-05-21

Position-controllable trapping of particles on the surface of a bipolar metal strip by induced-charge electroosmotic (ICEO) flow is presented herein. We demonstrate a nonlinear ICEO slip profile on the electrode surface accounting for stable particle trapping behaviors above the double-layer relaxation frequency, while no trapping occurs in the DC limit as a result of a strong upward fluidic drag induced by a linear ICEO slip profile. By extending an AC-flow field effect transistor from the DC limit to the AC field, we reveal that fixed-potential ICEO exceeding RC charging frequency can adjust the particle trapping position flexibly by generating controllable symmetry breaking in a vortex flow pattern. Our results open up new opportunities to manipulate microscopic objects in modern microfluidic systems by using ICEO.

Inter-conversion of Work and Heat With Plasma Electric Fields

NASA Astrophysics Data System (ADS)

Avinash, K.

2010-11-01

Thermodynamics of a model system where a group of cold charged particles locally confined in a volume VP within a warm plasma of temperature T and fixed volume V (VP<

The relationship between safety net activities and hospital financial performance

PubMed Central

2010-01-01

Background During the 1990's hospitals in the U.S were faced with cost containment charges, which may have disproportionately impacted hospitals that serve poor patients. The purposes of this paper are to study the impact of safety net activities on total profit margins and operating expenditures, and to trace these relationships over the 1990s for all U.S urban hospitals, controlling for hospital and market characteristics. Methods The primary data source used for this analysis is the Annual Survey of Hospitals from the American Hospital Association and Medicare Hospital Cost Reports for years 1990-1999. Ordinary least square, hospital fixed effects, and two-stage least square analyses were performed for years 1990-1999. Logged total profit margin and operating expenditure were the dependent variables. The safety net activities are the socioeconomic status of the population in the hospital serving area, and Medicaid intensity. In some specifications, we also included uncompensated care burden. Results We found little evidence of negative effects of safety net activities on total margin. However, hospitals serving a low socioeconomic population had lower expenditure raising concerns for the quality of the services provided. Conclusions Despite potentially negative policy and market changes during the 1990s, safety net activities do not appear to have imperiled the survival of hospitals. There may, however, be concerns about the long-term quality of the services for hospitals serving low socioeconomic population. PMID:20074367

Impact of a fixed price system on the supply of institutional long-term care: a comparative study of Japanese and German metropolitan areas.

PubMed

Yoshida, Keiko; Kawahara, Kazuo

2014-02-01

The need for institutional long-term care is increasing as the population ages and the pool of informal care givers declines. Care services are often limited when funding is controlled publicly. Fees for Japanese institutional care are publicly fixed and supply is short, particularly in expensive metropolitan areas. Those insured by universal long-term care insurance (LTCI) are faced with geographically inequitable access. The aim of this study was to examine the impact of a fixed price system on the supply of institutional care in terms of equity. The data were derived from official statistics sources in both Japan and Germany, and a self-administered questionnaire was used in Japan in 2011. Cross-sectional multiple regression analyses were used to examine factors affecting bed supply of institutional/residential care in fixed price and free prices systems in Tokyo (Japan), and an individually-bargained price system in North Rhine-Westphalia (Germany). Variables relating to costs and needs were used to test hypotheses of cost-dependency and need-orientation of bed supply in each price system. Analyses were conducted using data both before and after the introduction of LTCI, and the results of each system were qualitatively compared. Total supply of institutional care in Tokyo under fixed pricing was found to be cost-dependent regarding capital costs and scale economies, and negatively related to need. These relationships have however weakened in recent years, possibly caused by political interventions under LTCI. Supply of residential care in Tokyo under free pricing was need-oriented and cost-dependent only regarding scale economies. Supply in North Rhine-Westphalia under individually bargained pricing was cost-independent and not negatively related to need. Findings suggest that publicly funded fixed prices have a negative impact on geographically equitable supply of institutional care. The contrasting results of the non-fixed-price systems for Japanese residential care and German institutional care provide further theoretical supports for this and indicate possible solutions against inequitable supply.

Impact of a fixed price system on the supply of institutional long-term care: a comparative study of Japanese and German metropolitan areas

PubMed Central

2014-01-01

Background The need for institutional long-term care is increasing as the population ages and the pool of informal care givers declines. Care services are often limited when funding is controlled publicly. Fees for Japanese institutional care are publicly fixed and supply is short, particularly in expensive metropolitan areas. Those insured by universal long-term care insurance (LTCI) are faced with geographically inequitable access. The aim of this study was to examine the impact of a fixed price system on the supply of institutional care in terms of equity. Methods The data were derived from official statistics sources in both Japan and Germany, and a self-administered questionnaire was used in Japan in 2011. Cross-sectional multiple regression analyses were used to examine factors affecting bed supply of institutional/residential care in fixed price and free prices systems in Tokyo (Japan), and an individually-bargained price system in North Rhine-Westphalia (Germany). Variables relating to costs and needs were used to test hypotheses of cost-dependency and need-orientation of bed supply in each price system. Analyses were conducted using data both before and after the introduction of LTCI, and the results of each system were qualitatively compared. Results Total supply of institutional care in Tokyo under fixed pricing was found to be cost-dependent regarding capital costs and scale economies, and negatively related to need. These relationships have however weakened in recent years, possibly caused by political interventions under LTCI. Supply of residential care in Tokyo under free pricing was need-oriented and cost-dependent only regarding scale economies. Supply in North Rhine-Westphalia under individually bargained pricing was cost-independent and not negatively related to need. Conclusions Findings suggest that publicly funded fixed prices have a negative impact on geographically equitable supply of institutional care. The contrasting results of the non-fixed-price systems for Japanese residential care and German institutional care provide further theoretical supports for this and indicate possible solutions against inequitable supply. PMID:24485330

Multi-Skyrmions on AdS2 × S2, rational maps and popcorn transitions

NASA Astrophysics Data System (ADS)

Canfora, Fabrizio; Tallarita, Gianni

2017-08-01

By combining two different techniques to construct multi-soliton solutions of the (3 + 1)-dimensional Skyrme model, the generalized hedgehog and the rational map ansatz, we find multi-Skyrmion configurations in AdS2 ×S2. We construct Skyrmionic multi-layered configurations such that the total Baryon charge is the product of the number of kinks along the radial AdS2 direction and the degree of the rational map. We show that, for fixed total Baryon charge, as one increases the charge density on ∂ (AdS2 ×S2) , it becomes increasingly convenient energetically to have configurations with more peaks in the radial AdS2 direction but a lower degree of the rational map. This has a direct relation with the so-called holographic popcorn transitions in which, when the charge density is high, multi-layered configurations with low charge on each layer are favored over configurations with few layers but with higher charge on each layer. The case in which the geometry is M2 ×S2 can also be analyzed.

Atomic Charge Parameters for the Finite Difference Poisson-Boltzmann Method Using Electronegativity Neutralization.

PubMed

Yang, Qingyi; Sharp, Kim A

2006-07-01

An optimization of Rappe and Goddard's charge equilibration (QEq) method of assigning atomic partial charges is described. This optimization is designed for fast and accurate calculation of solvation free energies using the finite difference Poisson-Boltzmann (FDPB) method. The optimization is performed against experimental small molecule solvation free energies using the FDPB method and adjusting Rappe and Goddard's atomic electronegativity values. Using a test set of compounds for which experimental solvation energies are available and a rather small number of parameters, very good agreement was obtained with experiment, with a mean unsigned error of about 0.5 kcal/mol. The QEq atomic partial charge assignment method can reflect the effects of the conformational changes and solvent induction on charge distribution in molecules. In the second section of the paper we examined this feature with a study of the alanine dipeptide conformations in water solvent. The different contributions to the energy surface of the dipeptide were examined and compared with the results from fixed CHARMm charge potential, which is widely used for molecular dynamics studies.

A vacuum spark ion source: High charge state metal ion beams

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

Yushkov, G. Yu., E-mail: gyushkov@mail.ru; Nikolaev, A. G.; Frolova, V. P.

2016-02-15

High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less thanmore » 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described.« less

A new self-assembled layer-by-layer glucose biosensor based on chitosan biopolymer entrapped enzyme with nitrogen doped graphene.

PubMed

Barsan, Madalina M; David, Melinda; Florescu, Monica; Ţugulea, Laura; Brett, Christopher M A

2014-10-01

The layer-by-layer (LbL) technique has been used for the construction of a new enzyme biosensor. Multilayer films containing glucose oxidase, GOx, and nitrogen-doped graphene (NG) dispersed in the biocompatible positively-charged polymer chitosan (chit(+)(NG+GOx)), together with the negatively charged polymer poly(styrene sulfonate), PSS(-), were assembled by alternately immersing a gold electrode substrate in chit(+)(NG+GOx) and PSS(-) solutions. Gravimetric monitoring during LbL assembly by an electrochemical quartz microbalance enabled investigation of the adsorption mechanism and deposited mass for each monolayer. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the LbL modified electrodes, in order to establish the contribution of each monolayer to the overall electrochemical properties of the biosensor. The importance of NG in the biosensor architecture was evaluated by undertaking a comparative study without NG in the chit layer. The GOx biosensor's analytical properties were evaluated by fixed potential chronoamperometry and compared with similar reported biosensors. The biosensor operates at a low potential of -0.2V vs., Ag/AgCl, exhibiting a high sensitivity of 10.5 μA cm(-2) mM(-1), and a detection limit of 64 μM. This study shows a simple approach in developing new biosensor architectures, combining the advantages of nitrogen-doped graphene with the LbL technique for enzyme immobilization. Copyright © 2014 Elsevier B.V. All rights reserved.

Experimental investigation of the influence of nanoparticles on water-based mud

NASA Astrophysics Data System (ADS)

Dhiman, Paritosh; Cheng, Yaoze; Zhang, Yin; Patil, Shirish

2018-03-01

This study has investigated the influence of nanoparticles including nanoparticle concentration, size, and type on water-based mud (WBM) properties including rheology, filtration, and lubricity through experimental tests, while the influence of temperature and aging on these properties have been investigated. It has been found that adding SiO2 nanoparticles increase the plastic viscosity and decrease the yield points and gel strengths with the increase of nanoparticle concentration. At fixed 0.5 wt%, the plastic viscosity decreases with the increase of TiO2 nanoparticle size, but the influence of TiO2 nanoparticle size on yield points and gel strengths is not monotonous. In general, adding negative charged SiO2 nanoparticles reduce the yield points and gel strengths, while adding positively charged TiO2, Al2O3, and Fe3O4 nanoparticles increase yield points and gel strengths. Adding lower concentrations (< 0.05 wt%) of SiO2 nanoparticles improved mud filtration and lubricity properties, but higher concentrations are adverse to these properties and adding 0.5 wt% TiO2, Al2O3 and Fe3O4 nanoparticles impaired these properties. Besides, it is found that there is no consistent influence of aging on mud properties and adding nanoparticles cannot improve aging resistance of mud. Although adding nanoparticles can significantly affect WBM properties, their influences are not consistency, depending on the integrated impact of the nanoparticle properties, such as surface electrical property, specific surface area, concentration, and size.

In-situ investigations of the ionosphere of comet 67P

NASA Astrophysics Data System (ADS)

Eriksson, A. I.; Edberg, N. J. T.; Odelstad, E.; Vigren, E.; Engelhardt, I.; Henri, P.; Lebreton, J.-P.; Galand, M.; Carr, C. M.; Koenders, C.; Nilsson, H.; Broiles, T.; Rubin, M.

2015-10-01

Since arrival of Rosetta at its target comet 67P/Churyumov-Gerasimenko in August 2014, the plasma environment has been dominated by ionized gas emanating from the comet nucleus rather than by solar wind plasma. This was evident early on from the strong modulation seen with Rosetta's position in a reference frame fixed to the rotating nucleus, with higher plasma densities observed when the spacecraft is above the neck region and when the comet exposes maximum area to the sun. In this respect, Rosetta is inside the comet ionosphere, providing excellent in situ investigation opportunities for the instruments of the Rosetta Plasma Consortium (RPC). In contrast to the often modelled scenario for a very active comet, the Langmuir probe instrument (RPC-LAP) finds electron temperatures mainly in the range of tens of thousand kelvin around this less active comet. This can be attributed to the lower density of neutral gas, meaning little cooling of recently produced electrons. A side effect of this is that the spacecraft charges negatively when within about 100 km from the nucleus. Interesting in itself, this also may point to similar charging for dust grains in the coma, with implications for the detection of the smallest particles and possibly for processes like electrostatic fragmentation. The inner coma also proves to be very dynamic, with large variations not only with latitude and longitude in a comet frame, but also with the solar wind and various wave phenomena.

In vivo distribution and antitumor activity of heparin-stabilized doxorubicin-loaded liposomes.

PubMed

Han, Hee Dong; Lee, Aeri; Song, Chung Kil; Hwang, Taewon; Seong, Hasoo; Lee, Chong Ock; Shin, Byung Cheol

2006-04-26

The purpose of this study was to investigate the effect of heparin conjugation to the surface of doxorubicin (DOX)-loaded liposomes on the circulation time, biodistribution and antitumor activity after intravenous injection in murine B16F10 melanoma tumor-bearing mice. The heparin-conjugated liposomes (heparin-liposomes) were prepared by fixation of the negatively charged heparin to the positively charged liposomes. The existence of heparin on the liposomal surface was confirmed by measuring the changes in the particle size, zeta potential and heparin amount of the liposomes. The stability of the heparin-liposomes in serum was higher than that of the control liposomes, due to the heparin-liposomes being better protected from the adsorption of serum proteins. The DOX-loaded heparin-liposomes showed high drug levels for up to 64 h after the intravenous injection and the half-life of DOX was approximately 8.4- or 1.5-fold higher than that of the control liposomes or polyethyleneglycol-fixed liposomes (PEG-liposomes), respectively. The heparin-liposomes accumulated to a greater extent in the tumor than the control or PEG-liposomes as a result of their lower uptake by the reticuloendothelial system cells in the liver and spleen. In addition, the DOX-loaded heparin-liposomes retarded the growth of the tumor effectively compared with the control or PEG-liposomes. These results indicate the promising potential of heparin-liposomes as a new sterically stabilized liposomal delivery system for the enhancement of the therapeutic efficacy of chemotherapeutic agents.

Tantalum oxide/silicon nitride: A negatively charged surface passivation stack for silicon solar cells

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

Wan, Yimao, E-mail: yimao.wan@anu.edu.au; Bullock, James; Cuevas, Andres

2015-05-18

This letter reports effective passivation of crystalline silicon (c-Si) surfaces by thermal atomic layer deposited tantalum oxide (Ta{sub 2}O{sub 5}) underneath plasma enhanced chemical vapour deposited silicon nitride (SiN{sub x}). Cross-sectional transmission electron microscopy imaging shows an approximately 2 nm thick interfacial layer between Ta{sub 2}O{sub 5} and c-Si. Surface recombination velocities as low as 5.0 cm/s and 3.2 cm/s are attained on p-type 0.8 Ω·cm and n-type 1.0 Ω·cm c-Si wafers, respectively. Recombination current densities of 25 fA/cm{sup 2} and 68 fA/cm{sup 2} are measured on 150 Ω/sq boron-diffused p{sup +} and 120 Ω/sq phosphorus-diffused n{sup +} c-Si, respectively. Capacitance–voltage measurements reveal a negativemore » fixed insulator charge density of −1.8 × 10{sup 12 }cm{sup −2} for the Ta{sub 2}O{sub 5} film and −1.0 × 10{sup 12 }cm{sup −2} for the Ta{sub 2}O{sub 5}/SiN{sub x} stack. The Ta{sub 2}O{sub 5}/SiN{sub x} stack is demonstrated to be an excellent candidate for surface passivation of high efficiency silicon solar cells.« less

Characteristics of M-component in rocket-triggered lightning and a discussion on its mechanism

NASA Astrophysics Data System (ADS)

Jiang, Rubin; Qie, Xiushu; Yang, Jing; Wang, Caixia; Zhao, Yang

2013-09-01

The current and electric field pulses associated with M-component following dart leader-return stroke sequences in negative rocket-triggered lightning flashes were analyzed in detail by using the data from Shandong Artificially Triggering Lightning Experiment, conducted from 2005 to 2010. For 63 M-components with current waveforms superimposed on the relatively steady continuing current, the geometric mean values of the peak current, duration, and charge transfer were 276 A, 1.21 ms, and 101 mC, respectively. The behaviors of the channel base current versus close electric field changes and the observation facts by different authors were carefully examined for investigation on mechanism of the M-component. A modified model based on Rakov's "two-wave" theory is proposed and confirms that the evolution of M-component through the lightning channel involves a downward wave transferring negative charge from the upper to the lower channel and an upward wave draining the charge transported by the downward wave. The upward wave serves to deplete the negative charge by the downward wave at its interface and makes the charge density of the channel beneath the interface layer to be roughly zero. Such modified concept is recognized to be reasonable by the simulated results showing a good agreement between the calculated and the measured E-field waveforms.