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Sample records for influence des ions

  1. Gas-phase basicities for ions from bradykinin and its des-arginine analogues.

    PubMed

    Ewing, N P; Pallante, G A; Zhang, X; Cassady, C J

    2001-08-01

    Apparent gas-phase basicities (GB(app)s) for [M + H]+ of bradykinin, des-Arg1-bradykinin and des-Arg9-bradykinin have been assigned by deprotonation reactions of [M + 2H]2+ in a Fourier transform ion cyclotron resonance mass spectrometer. With a GB(app) of 225.8 +/- 4.2 kcal x mol(-1), bradykinin [M + H]+ is the most basic of the ions studied. Ions from des-Arg1-bradykinin and des-Arg9-bradykinin have GB(app) values of 222.8 +/- 4.3 kcal x mol(-1) and 214.9 +/- 2.3 kcal x mol(-1), respectively. One purpose of this work was to determine a suitable reaction efficiency 'break point' for assigning GB(app) values to peptide ions using the bracketing method. An efficiency value of 0.1 (i.e. approximately 10% of all collisions resulting in a deprotonation reaction) was used to assign GB(app)s. Support for this criterion is provided by the fact that our GB(app) values for des-Arg1-bradykinin and des-Arg9-bradykinin are identical, within experimental error, to literature values obtained using a modified kinetic method. However, the GB(app)s for bradykinin ions from the two studies differ by 10.3 kcal x mol(-1). The reason for this is not clear, but may involve conformation differences produced by experimental conditions. The results may be influenced by salt-bridge conformers and/or by conformational changes caused by the use of a proton-bound heterodimer in the kinetic method. Factors affecting the basicities of these peptide ions are also discussed, and molecular modeling is used to provide information on protonation sites and conformations. The presence of two highly basic arginine residues on bradykinin results in its high GB(app), while the basicity of des-Arg1-bradykinin ions is increased by the presence of two proline residues at the N-terminus. The proline residue in the second position folds the peptide chain in a manner that increases intramolecular hydrogen bonding to the protonated N-terminal amino group of the proline at the first position. PMID:11523086

  2. Copernic: la piste des influences arabes

    NASA Astrophysics Data System (ADS)

    Khalatbari, A.; Bonnet-Bidaud, J. M.

    2004-10-01

    Copernic a-t-il connu le travail des astronomes du Moyen-Orient ? S'en est-il inspiré pour élaborer sa théorie de l'héliocentrisme ? C'est l'hypothèse avancée par certains historiens des sciences pour comprendre le génie de celui qui, le premier, a placé le Soleil au centre du monde. Enquête.

  3. Ion Exchange Membrane Influence on Ohmic Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Selection of the proper ion exchange membrane can have a significant influence on bioelectrochemical system (BES) power densities. Because ions move across the membrane to achieve electroneutrality, the ion transport resistance (ohmic loss) needs to be minimized to increase power densities. Ohmic ...

  4. Influence of Reverse Expansion of Laser Plasma on Ions Acceleration

    NASA Astrophysics Data System (ADS)

    Sysoev, Alexander A.; Gracheva, O. I.; Karpov, A. V.

    Effect of laser plasma reverse extension is described in this paper. Influence of the effect on ion acceleration in a laser ion source is researched. This effect leads to sedimentation of ions on metal target, which significantly impacts acceleration time of other ions. In this case, the ions also tend to travel major part of their path with constant velocity. This allows one to consider movement of the ions in plasma drift space, when optimizing time focusing ability of the TOF analyzer.

  5. Les reseaux de politique publique comme facteur d'influence du choix des instruments de politique energetique canadienne a des fins environnementales de 1993 a nos jours

    NASA Astrophysics Data System (ADS)

    Fathy El Dessouky, Naglaa

    l'agenda politique du pays. Notre projet de recherche, par le truchement de l'approche des reseaux de politique publique, s'attarde a decrire et a expliquer le processus de la formulation d'une politique particuliere, soit la politique energetique a des fins de protection de l'environnement, elaboree en 1993. Il s'agit de mettre en evidence les facteurs affectant le choix des instruments de ces politiques publiques dans leur contexte national. Ainsi, la question generale de cette recherche est: Comment les phases evolutives de la formation d'un reseau de politique, en l'occurrence le Conseil canadien de l'energie (CCE), menent a des caracteristiques particulieres a ce reseau; et comment celles-ci determinent-elles les types des instruments de politique publique choisis, particulierement ceux de la recente orientation des politiques energetiques canadiennes a des fins environnementales elaborees en 1993? Afin d'atteindre l'objectif de notre recherche, deux facteurs primordiaux sont utilises, soit la circulation de l'information et l'exercice du controle sur les ressources des acteurs. L'analyse des caracteristiques du reseau en fonction des liens forts et des liens faibles autant que la presence ou l'absence des trous structuraux nous permettent de bien identifier les positions des differents acteurs, etatiques et non etatiques, sur le plan de l'information et du controle, qui a leur tour, nous semble-t-il, constituent des facteurs affectant les types des instruments des politiques publiques choisis: instruments substantifs, qui indiquent le degre de l'intervention du gouvernement, et instruments proceduraux, qui mettent plutot l'accent sur le degre de l'influence du gouvernement sur les acteurs non etatiques. L'etude soutient que l'approche des reseaux se distingue notamment par son potentiel a expliquer l'interrelation relative entre idees, interets et institutions, ce qui a son tour est susceptible de permettre une meilleure comprehension des processus de l

  6. Influence of ion streaming instabilities on transport near plasma boundaries

    NASA Astrophysics Data System (ADS)

    Baalrud, Scott D.

    2016-04-01

    Plasma boundary layers are susceptible to electrostatic instabilities driven by ion flows in presheaths and, when present, these instabilities can influence transport. In plasmas with a single species of positive ion, ion-acoustic instabilities are expected under conditions of low pressure and large electron-to-ion temperature ratio ({{T}e}/{{T}i}\\gg 1 ). In plasmas with two species of positive ions, ion-ion two-stream instabilities can also be excited. The stability phase-space is characterized using the Penrose criterion and approximate linear dispersion relations. Predictions for how these instabilities affect ion and electron transport in presheaths, including rapid thermalization due to instability-enhanced collisions and an instability-enhanced ion-ion friction force, are briefly reviewed. Recent experimental tests of these predictions are discussed along with research needs required for further validation. The calculated stability boundaries provide a guide to determine the experimental conditions at which these effects can be expected.

  7. Characterization of drug-eluting stent (DES) materials with cluster secondary ion mass spectrometry (SIMS)

    NASA Astrophysics Data System (ADS)

    Mahoney, Christine M.; Patwardhan, Dinesh V.; Ken McDermott, M.

    2006-07-01

    Secondary ion mass spectrometry (SIMS) employing an SF 5+ polyatomic primary ion source was utilized to analyze several materials commonly used in drug-eluting stents (DES). Poly(ethylene- co-vinyl acetate) (PEVA), poly(lactic- co-glycolic acid) (PLGA) and various poly(urethanes) were successfully depth profiled using SF 5+ bombardment. The resultant molecular depth profiles obtained from these polymeric films showed very little degradation in molecular signal as a function of increasing SF 5+ primary ion dose when experiments were performed at low temperatures (signal was maintained for doses up to ˜5 × 10 15 ions/cm 2). Temperature was determined to be an important parameter in both the success of the depth profiles and the mass spectral analysis of the polymers. In addition to the pristine polymer films, paclitaxel (drug released in Taxus™ stent) containing PLGA films were also characterized, where it was confirmed that both drug and polymer signals could be monitored as a function of depth at lower paclitaxel concentrations (10 wt%).

  8. Influence of Energetic Ions on Tearing Modes

    SciTech Connect

    Cai Huishan; Wang Shaojie; Xu Yinfeng; Cao Jintao; Li Ding

    2011-02-18

    In contrast with the stability effects of trapped energetic ions on tearing modes, the effects of circulating energetic ions (CEI) on tearing modes depend on the toroidal circulating direction, and are closely related to the momentum of energetic ions. CEI provide an additional source or sink of momentum to affect tearing modes. For co-CEI, tearing modes can be stabilized if the momentum of energetic ions is large enough. On the other hand, the growth of tearing modes can be enhanced by counter-CEI. Further, a possibility to suppress the island growth of neoclassical tearing modes by co-CEI is pointed out.

  9. Influence of higher valent ions on flexible polyelectrolyte stiffness and counter-ion distribution

    NASA Astrophysics Data System (ADS)

    Chremos, Alexandros; Douglas, Jack F.

    2016-04-01

    We investigate the influence of counter-ion valency on the flexibility of highly charged flexible polymer chains using molecular dynamics simulations that include both salt and an explicit solvent. As observed experimentally, we find that divalent counter-ions greatly reduce the chain persistence length, lp, in comparison with monovalent counter-ions. On the other hand, polyelectrolyte chains having trivalent counter-ions adopt a much more compact conformation than polyelectrolytes having monovalent and divalent counter-ions. We demonstrate that the tendency of polyelectrolyte chains to become deformed by proximal high valence counter-ions is due to chain "coiling" around the counter-ions. In particular, we find that the number of contacts that the proximal counter-ions have with the polyelectrolyte dictates the extent of chain coiling. This ion-binding induced coiling mechanism influences not only the conformational properties of the polyelectrolyte, but also the counter-ion distribution around the chain. Specifically, we find that higher valent counter-ions lead both to a counter-ion enrichment in close proximity to the polyelectrolyte and to a significant reduction in the spatial extent of the diffuse counter-ion cloud around the polyelectrolyte.

  10. Influence of higher valent ions on flexible polyelectrolyte stiffness and counter-ion distribution.

    PubMed

    Chremos, Alexandros; Douglas, Jack F

    2016-04-28

    We investigate the influence of counter-ion valency on the flexibility of highly charged flexible polymer chains using molecular dynamics simulations that include both salt and an explicit solvent. As observed experimentally, we find that divalent counter-ions greatly reduce the chain persistence length, lp, in comparison with monovalent counter-ions. On the other hand, polyelectrolyte chains having trivalent counter-ions adopt a much more compact conformation than polyelectrolytes having monovalent and divalent counter-ions. We demonstrate that the tendency of polyelectrolyte chains to become deformed by proximal high valence counter-ions is due to chain "coiling" around the counter-ions. In particular, we find that the number of contacts that the proximal counter-ions have with the polyelectrolyte dictates the extent of chain coiling. This ion-binding induced coiling mechanism influences not only the conformational properties of the polyelectrolyte, but also the counter-ion distribution around the chain. Specifically, we find that higher valent counter-ions lead both to a counter-ion enrichment in close proximity to the polyelectrolyte and to a significant reduction in the spatial extent of the diffuse counter-ion cloud around the polyelectrolyte. PMID:27131566

  11. Evaluation of the Influence of Beam Ions Exhausted from Ion Thrusters on Earth's Environment and Communication

    NASA Astrophysics Data System (ADS)

    Yamagiwa, Yoshiki; Kumatani, Yasuhiro; Miyamoto, Shigehiro; Otsu, Hirotaka

    The influence of exhausted beam ions from ion thrusters on Earth's environment and communication was analyzed by the detailed modeling of the exhausted ions' and electrons' motion and the energy exchange process between the exhausted ions and the circumferential particles. The analytical results showed that the density distribution of plasma components near the earth will change locally by the energy input of exhausted ions trapped by the geomagnetic field if the large scale operation of ion thrusters is performed, but its influence on earth's environment will be small compared with that by the natural phenomena such a magnetic storm. However, the influence on GPS communication will be large and the electrical charge of spacecraft will be progressed.

  12. Protection des ions organiques contre les dommages induits a l'ADN par les electrons de basse energie

    NASA Astrophysics Data System (ADS)

    Dumont, Ariane

    Il a ete demontre que les electrons de basse energie (EBE) peuvent induire des cassures simple brin (CSB) a l'ADN, via la formation d'anions transitoires qui decroissent par attachement dissociatif, ou dans d'autres etats electroniques dissociatifs menant a la fragmentation. Afin d'effectuer une etude complete des effets des electrons de basse energie sur la matiere biologique, il est necessaire de comprendre leur mecanismes d'interaction non seulement avec l'ADN, mais avec les constituants de son environnement. Les histones sont une composante importante de l'environnement moleculaire de l'ADN. Leur charge positive leur permet de s'associer aux groupements phosphate anionique de l'ADN. Le role principal de ces proteines basiques consiste a organiser l'ADN et l'empaqueter afin de former la chromatine. Les cations sont une autre composante importante de la cellule; ils jouent un role dans la stabilisation de la conformation B de l'ADN in vitro par leurs interactions avec les petits et grands sillons de l'ADN, ainsi qu'avec le groupement phosphate charge negativement. Avec les histones, ils participent egalement a la compaction de l'ADN pour former la chromatine. Cette etude a pour but de comprendre comment la presence d'ions organiques (sous forme de Tris et d'EDTA) a proximite de l'ADN modifie le rendement de cassures simple brin induit par les electrons de basse energie. Le Tris et l'EDTA ont-ete choisis comme objet d'etude, puisqu'en solution, ils forment le tampon standard pour solubiliser l'ADN dans les experiences in vitro (10mM Tris, 1mM EDTA). De plus, la molecule Tris possede un groupement amine alors que l'EDTA possede 4 groupements carboxyliques. Ensembles, ils peuvent se comporter comme un modele simple pour les acides amines. Le ratio molaire de 10 :1 de Tris par rapport a l'EDTA a pour but d'imiter le comportement des histones qui sont riches en arginine et lysine, acides amines possedant un groupement amine charge positivement additionnel. Des films d

  13. Influence of Higher Valence Ions on Flexible Polyelectrolytes Stiffness and Counter-ion Distribution

    NASA Astrophysics Data System (ADS)

    Chremos, Alexandros; Douglas, Jack F.

    We investigate the influence of counter-ion valency on the flexibility of highly charged flexible polymer chains by molecular dynamics simulations that include both salt and an explicit solvent. A theoretical understanding of solutions of these molecules (e.g., DNA, RNA, and sulfonate polyestyrene) has been slow to develop due to the complex coupling between the polyelectrolyte conformation and the ionic species in solution due to their long range Coulomb interactions. As observed experimentally, we find that divalent counter-ions greatly reduce the chain persistence length, in comparison to monovalent counter-ions, an effect correlated with the tendency of the polyelectrolyte chain to become distorted by divalent counter-ions. We rationalize these results by with the substantial increase of counter-ion population at the interface with the polyelectrolyte, which not only leads to a more effective screening of the bare charge, but also leads to charge inversion in the trivalent counter-ion case. These conformational changes with counter-ion valency are also associated with a drastic increase of the number of contacts the counter-ions have at the interface with polyelectrolyte, an effect associated with polyelectrolyte chain ``coiling'' around the counter-ions. NIST Postdoctoral Fellowship.

  14. The influence of stray magnetic fields on ion beam neutralization

    NASA Technical Reports Server (NTRS)

    Feng, Y.-C.; Wilbur, P. J.

    1982-01-01

    An experimental investigation is described of a comparison between the ion beam neutralization characteristics of a local neutralizer (within approximately 5 cm of the beam edge) and those associated with a distant one (approximately 1 meter away from the thruster). The influence of magnetic fields in the vicinity of the neutralizer cathode orifice which are either parallel or normal to the neutralizer axis is assessed. The plasma property profiles which reflect the influence of the magnetic fields are measured. The results suggest that magnetic fields at the region of a neutralizer cathode orifice influence its ability to couple to the ion beam. They reveal that there is a potential jump from the neutralizer cathode orifice to the plasma which exists close to the orifice. This potential drop is found to increase as the axial component of magnetic flux density increases. A magnetic field perpendicular to the neutralizer axis induces a potential rise a few centimeters downstream from the neutralizer cathode.

  15. Influence of nonelectrostatic ion-ion interactions on double-layer capacitance

    NASA Astrophysics Data System (ADS)

    Zhao, Hui

    2012-11-01

    Recently a Poisson-Helmholtz-Boltzmann (PHB) model [Bohinc , Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.85.031130 85, 031130 (2012)] was developed by accounting for solvent-mediated nonelectrostatic ion-ion interactions. Nonelectrostatic interactions are described by a Yukawa-like pair potential. In the present work, we modify the PHB model by adding steric effects (finite ion size) into the free energy to derive governing equations. The modified PHB model is capable of capturing both ion specificity and ion crowding. This modified model is then employed to study the capacitance of the double layer. More specifically, we focus on the influence of nonelectrostatic ion-ion interactions on charging a double layer near a flat surface in the presence of steric effects. We numerically compute the differential capacitance as a function of the voltage under various conditions. At small voltages and low salt concentrations (dilute solution), we find out that the predictions from the modified PHB model are the same as those from the classical Poisson-Boltzmann theory, indicating that nonelectrostatic ion-ion interactions and steric effects are negligible. At moderate voltages, nonelectrostatic ion-ion interactions play an important role in determining the differential capacitance. Generally speaking, nonelectrostatic interactions decrease the capacitance because of additional nonelectrostatic repulsion among excess counterions inside the double layer. However, increasing the voltage gradually favors steric effects, which induce a condensed layer with crowding of counterions near the electrode. Accordingly, the predictions from the modified PHB model collapse onto those computed by the modified Poisson-Boltzmann theory considering steric effects alone. Finally, theoretical predictions are compared and favorably agree with experimental data, in particular, in concentrated solutions, leading one to conclude that the modified PHB model adequately predicts the diffuse

  16. Influence of solar wind ions on photoemission charging of dust

    NASA Astrophysics Data System (ADS)

    Nouzak, Libor; Richterova, Ivana; Pavlu, Jiri; Safrankova, Jana; Nemecek, Zdenek

    2016-04-01

    The lunar surface covered by a layer of dust grains is exposed to solar wind particles and photons coming from the Sun on the sunlit side. Solar wind ions cause sputtering of dust grains or can be implanted into grains. We suppose that as a consequence of ion implantation, an additional energy is transferred to grains, more valence band electrons are excited, and the photoelectron yield is increased. An increase of the photoelectron current causes the enhanced density of electrons that form a sheet above the illuminated lunar surface. Thus, an influence of solar wind ions on the Debye length and photoelectron sheet formation is expected. We present laboratory estimations of work functions and photoelectron yields of a single micron-sized silica grain before and after ion implantation. The silica grain used as a lunar simulant is caught in the electrodynamic trap. Grain's specific charge is evaluated by an analysis of the grain motion within the trap, while its work function is determined from observations of a time evolution of the charge-to-mass ratio when the grain is irradiated by photons of different emission lines. By comparison of the photoelectron current (from grain) with photon flux (from UV source), we establish the photoelectron yield of the trapped object. The influence of ion implantation is thoroughly analyzed and discussed.

  17. Influence of cadmium ions on plasticity of steel under pickling

    SciTech Connect

    Matuiichuk, A.Y.; Eskazina, R.S.; Levinson, Z.F.; Shmaneva, N.Y.; Zhakupova, A.S.

    1986-07-01

    The authors study how cadmium ions influence the plasticity of steel during pickling. The specimens were rods 0.8 mm diameter, 120 mm long, of steel KT-2, and were pickled for 30 min at 25 c in solutions of sulfuric acid and ferric sulfate, then washed with water and subjected to twisting. It is shown that when the sulfuric acid concentration is altered from 60 to 180 g/liter the fall in plasticity changes from 12.6 to 23.0%. In the presence of at least 10 g/liter of cadmium sulfate in the same solutions the fall in plasticity decreases to 4.6-8%. Thus, cadmium ions have a marked influence on the plasticity of steel in pickling in sulfuric acid solutions at low temperatures.

  18. Dépistage des maladies cardiovasculaires chez des étudiants de l'Université de Douala et influence des activités physiques et sportives

    PubMed Central

    Ewane, Marielle Epacka; Mandengue, Samuel Honoré; Priso, Eugene Belle; Tamba, Stéphane Moumbe; Ahmadou; Fouda, André Bita

    2012-01-01

    Introduction Les maladies cardiovasculaires (MCV) constituent l'une des principales causes de mortalité dans les pays en développement. Le dépistage de ces dernières chez des jeunes est un défi dans la lutte contre leur expansion. Le but de cette étude était de dépister ces maladies au sein d'une population jeunes d’étudiants camerounais. Methodes Deux mille six cent cinquante-huit étudiants de l'Université de Douala (23,6 ± 2,9 ans, sex-ratio H/F = 0,9) ont en Avril - Mai 2011 participé à une campagne de dépistage gratuit du diabète, de l'hypertension artérielle (HTA) et de l'obésité. Ils ont également été soumis à une d'enquête évaluant leur niveau en activités physiques et sportives (APS). Resultats 12,7% des participants avaient une pression artérielle (PA) ≥ 140/90 mmHg, 3,6% étaient obèses et 0,9% avaient une glycémie ≥1,26 g/L. Des corrélations ont été trouvées entre certains facteurs de risque (diabète, hypertension et obésité) et le niveau académique d'une part (r =0,366; p < 0,0001) et le temps passé devant la télévision d'autres part (r = 0,411; p < 0,0001). L‘APS était inversement corrélée à l‘âge (r =-0,015; p < 0,0001) et au temps passé devant la télévision (r = -0,059; p = 0,002). Conclusion La présence des MCV et leurs facteurs de risque mis en évidence dans cette étude réalisée en milieu estudiantin camerounais interpelle à une prévention et une éducation dans la lutte contre ces dernières. PMID:22655111

  19. Influence of ion size and charge on osmosis.

    PubMed

    Cannon, James; Kim, Daejoong; Maruyama, Shigeo; Shiomi, Junichiro

    2012-04-12

    Osmosis is fundamental to many processes, such as in the function of biological cells and in industrial desalination to obtain clean drinking water. The choice of solute in industrial applications of osmosis is highly important in maximizing efficiency and minimizing costs. The macroscale process of osmosis originates from the nanoscale properties of the solvent, and therefore an understanding of the mechanisms of how these properties determine osmotic strength can be highly useful. For this reason, we have undertaken molecular dynamics simulations to systematically study the influence of ion size and charge on the strength of osmosis of water through carbon nanotube membranes. Our results show that strong osmosis occurs under optimum conditions of ion placement near the region of high water density near the membrane wall and of maintenance of a strong water hydration shell around the ions. The results in turn allow greater insight into the origin of the strong osmotic strength of real ions such as NaCl. Finally, in terms of practical simulation, we highlight the importance of avoiding size effects that can occur if the simulation cell is too small. PMID:22397596

  20. Influence of ion implantation on titanium surfaces for medical applications

    NASA Astrophysics Data System (ADS)

    Krischok, Stefan; Blank, Claudia; Engel, Michael; Gutt, Richard; Ecke, Gernot; Schawohl, Jens; Spieß, Lothar; Schrempel, Frank; Hildebrand, Gerhard; Liefeith, Klaus

    2007-09-01

    The implantation of ions into the near surface layer is a new approach to improve the osseointegration of metallic biomaterials like titanium. Meanwhile it is well known that surface topography and surface physico-chemistry as well as visco-elastic properties influence the cell response after implantation of implants into the human body. To optimize the cell response of titanium, ion implantation techniques have been used to integrate calcium and phosphorus, both elements present in the inorganic bone phase. In this context, the concentration profile of the detected elements and their chemical state have been investigated using X-ray photoelectron spectroscopy and Auger electron spectroscopy depth profiling. Ion implantation leads to strong changes of the chemical composition of the near surface region, which are expected to modify the biofunctionality as observed in previous experiments on the cell response. The co-implantation of calcium and phosphorus samples, which showed best results in the performed tests (biological and physical), leads to a strong modification of the chemical surface composition.

  1. Influence of proximal drug eluting stent (DES) on distal bare metal stent (BMS) in multi-stent implantation strategies in coronary arteries.

    PubMed

    Sun, Anqiang; Wang, Zhenze; Fan, Zhenmin; Tian, Xiaopeng; Zhan, Fan; Deng, Xiaoyan; Liu, Xiao

    2015-09-01

    The aim of this study was to investigate the drug distribution in arteries treated with DES-BMS stenting strategy and to analyze the influence of proximal DES on distal segments of BMS. A straight artery model (Straight Model) and a branching artery model (Branching Model) were constructed in this study. In each model, the DES was implanted at the proximal position and the BMS was implanted distally. Hemodynamic environments, drug delivery and distribution features were simulated and analyzed in each model. The results showed that blood flow would contribute to non-uniform drug distribution in arteries. In the Straight Model the proximal DES would cause drug concentration in BMS segments. While in the Branching Model the DES in the main artery has slight influence on the BMS segments in the branch artery. In conclusion, due to the blood flow washing effect the uniformly released drug from DES would distribute focally and distally. The proximal DES would have greater influence on the distal BMS in straight artery than that in branching artery. This preliminary study would provide good reference for atherosclerosis treatment, especially for some complex cases, like coronary branching stenting. PMID:26149391

  2. Influence du comportement des accompagnants sur le vécu des patients admis pour hémorragies digestives hautes au CHU campus de Lomé (Togo)

    PubMed Central

    Bagny, Aklesso; Dusabe, Angelique; Bouglouga, Oumboma; Lawson-ananisoh, Mawuli Late; Kaaga, Yeba Laconi; Djibril, Mohaman Awalou; Soedje, Kokou Mensah; Dassa, Simliwa Kolou; Redah, Datouda

    2014-01-01

    Introduction L'hémorragie digestive haute est une urgence, qui constitue souvent pour les patients un danger mortel suscitant inquiétude et agitation. Dans cet état, le patient dépend de ses accompagnants pour ses soins et pour honorer le traitement; mais souvent, il a été observé une discordance entre l'urgence et les comportements des accompagnants. Le but de cette étude était de décrire les facteurs socioéconomiques et psychologiques pouvant influencer les comportements des accompagnants des patients admis pour HDH, estimer l'indice de relation entre ces comportements et les facteurs associés d'une part et le vécu des patients admis pour HDH d'autre part. Méthodes Il s'agit d'une étude prospective menée de Septembre 2010 à Juin 2011 (soit 10 mois). Nous avions utilisé l'entretien semi-dirigé et l'observation directe pour collecter nos données, ces dernières avaient été traitées par les méthodes statistiques et d'analyse de contenu. Résultats Dans la présente étude, les comportements des accompagnants des patients admis pour HDH sont en majorité marqués par l'abandon (84%) et le manque de sollicitude (80,2%). Ces comportements sont souvent stimulés par les facteurs socioéconomiques tels que les difficultés économiques (83,2%), des conflits intrafamiliaux (85,1%) et des représentations (maladie incurable ou envoûtement) de la maladie par les accompagnants (73,3%) des cas. Quant aux patients, ils vivent ces comportements comme étant des menaces de mort ou des rejets (77,20%) et comme étant une dévalorisation ou une humiliation de la part de leurs accompagnants (70,30%). Les résultats confirment l'existence de lien significatif entre les comportements des accompagnants et les facteurs socio économiques, entre les comportements des accompagnants et des facteurs psychologiques, et entre le vécu des patients admis pour l'HDH et les comportements des accompagnants. Conclusion Des études ultérieures devraient aborder les points

  3. Influence of lead ions on the macromorphology of electrodeposited zinc

    SciTech Connect

    Tsuda, T.; Tobias, C.W.

    1981-09-01

    The morphology of zinc as it is electrodeposited from acid solutions demonstrates a remarkable imprint of electrolyte flow conditions. The development of macromorphology of zinc deposits has been investigated under galvanostatic conditions on a rotating plantinum disk electrode by use of photomacrography, scanning electron microscopy, electron probe microanalysis and Auger microprobe analysis. Logarithmic spiral markings, which reflect the hydrodynamic flow on a rotating disk, appear in a certain region of current density well below the limiting current density. Morphological observations revealed the major influence of trace lead ions on the amplifications of surface roughness through coalescence and preferred growth of initial protrusions. Results obtained from ultra-pure electrolyte suggest preferred crystal growth towards well-mixed orientation in the concentration field caused by slight differences in crystallization overpotential. A qualitative model involving a coupling mechanism between the evolving surface roughness and instability phenomena in the boundary layer is advanced to explain the formation of spiral patterns.

  4. Examining the Influence of Phosphorylation on Peptide Ion Structure by Ion Mobility Spectrometry-Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Glover, Matthew S.; Dilger, Jonathan M.; Acton, Matthew D.; Arnold, Randy J.; Radivojac, Predrag; Clemmer, David E.

    2016-02-01

    Ion mobility spectrometry-mass spectrometry (IMS-MS) techniques are used to study the general effects of phosphorylation on peptide structure. Cross sections for a library of 66 singly phosphorylated peptide ions from 33 pairs of positional isomers, and unmodified analogues were measured. Intrinsic size parameters (ISPs) derived from these measurements yield calculated collision cross sections for 85% of these phosphopeptide sequences that are within ±2.5% of experimental values. The average ISP for the phosphoryl group (0.64 ± 0.05) suggests that in general this moiety forms intramolecular interactions with the neighboring residues and peptide backbone, resulting in relatively compact structures. We assess the capability of ion mobility to separate positional isomers (i.e., peptide sequences that differ only in the location of the modification) and find that more than half of the isomeric pairs have >1% difference in collision cross section. Phosphorylation is also found to influence populations of structures that differ in the cis/trans orientation of Xaa-Pro peptide bonds. Several sequences with phosphorylated Ser or Thr residues located N-terminally adjacent to Pro residues show fewer conformations compared to the unmodified sequences.

  5. Examining the Influence of Phosphorylation on Peptide Ion Structure by Ion Mobility Spectrometry-Mass Spectrometry.

    PubMed

    Glover, Matthew S; Dilger, Jonathan M; Acton, Matthew D; Arnold, Randy J; Radivojac, Predrag; Clemmer, David E

    2016-05-01

    Ion mobility spectrometry-mass spectrometry (IMS-MS) techniques are used to study the general effects of phosphorylation on peptide structure. Cross sections for a library of 66 singly phosphorylated peptide ions from 33 pairs of positional isomers, and unmodified analogues were measured. Intrinsic size parameters (ISPs) derived from these measurements yield calculated collision cross sections for 85% of these phosphopeptide sequences that are within ±2.5% of experimental values. The average ISP for the phosphoryl group (0.64 ± 0.05) suggests that in general this moiety forms intramolecular interactions with the neighboring residues and peptide backbone, resulting in relatively compact structures. We assess the capability of ion mobility to separate positional isomers (i.e., peptide sequences that differ only in the location of the modification) and find that more than half of the isomeric pairs have >1% difference in collision cross section. Phosphorylation is also found to influence populations of structures that differ in the cis/trans orientation of Xaa-Pro peptide bonds. Several sequences with phosphorylated Ser or Thr residues located N-terminally adjacent to Pro residues show fewer conformations compared to the unmodified sequences. Graphical Abstract ᅟ. PMID:26860087

  6. Examining the Influence of Phosphorylation on Peptide Ion Structure by Ion Mobility Spectrometry-Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Glover, Matthew S.; Dilger, Jonathan M.; Acton, Matthew D.; Arnold, Randy J.; Radivojac, Predrag; Clemmer, David E.

    2016-05-01

    Ion mobility spectrometry-mass spectrometry (IMS-MS) techniques are used to study the general effects of phosphorylation on peptide structure. Cross sections for a library of 66 singly phosphorylated peptide ions from 33 pairs of positional isomers, and unmodified analogues were measured. Intrinsic size parameters (ISPs) derived from these measurements yield calculated collision cross sections for 85% of these phosphopeptide sequences that are within ±2.5% of experimental values. The average ISP for the phosphoryl group (0.64 ± 0.05) suggests that in general this moiety forms intramolecular interactions with the neighboring residues and peptide backbone, resulting in relatively compact structures. We assess the capability of ion mobility to separate positional isomers (i.e., peptide sequences that differ only in the location of the modification) and find that more than half of the isomeric pairs have >1% difference in collision cross section. Phosphorylation is also found to influence populations of structures that differ in the cis/ trans orientation of Xaa-Pro peptide bonds. Several sequences with phosphorylated Ser or Thr residues located N-terminally adjacent to Pro residues show fewer conformations compared to the unmodified sequences.

  7. Influence of nanoparticle-ion and nanoparticle-polymer interactions on ion transport and viscoelastic properties of polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Mogurampelly, Santosh; Sethuraman, Vaidyanathan; Pryamitsyn, Victor; Ganesan, Venkat

    2016-04-01

    We use atomistic simulations to probe the ion conductivities and mechanical properties of polyethylene oxide electrolytes containing Al2O3 nanoparticles. We specifically study the influence of repulsive polymer-nanoparticle and ion-nanoparticle interactions and compare the results with those reported for electrolytes containing the polymorph β-Al2O3 nanoparticles. We observe that incorporating repulsive nanoparticle interactions generally results in increased ionic mobilities and decreased elastic moduli for the electrolyte. Our results indicate that both ion transport and mechanical properties are influenced by the polymer segmental dynamics in the interfacial zones of the nanoparticle in the ion-doped systems. Such effects were seen to be determined by an interplay between the nanoparticle-polymer, nanoparticle-ion, and ion-polymer interactions. In addition, such interactions were also observed to influence the number of dissociated ions and the resulting conductivities. Within the perspective of the influence of nanoparticles on the polymer relaxation times in ion-doped systems, our results in the context of viscoelastic properties were consistent with the ionic mobilities. Overall, our results serve to highlight some issues that confront the efforts to use nanoparticle dispersions to simultaneously enhance the conductivity and the mechanical strength of polymer electrolyte.

  8. Excrétion rénale des ions divalents après homotransplantation rénale

    PubMed Central

    Cartier, F.; Popovtzer, M. M.; Robinette, J.; Pinggera, W. F.; Halgrimson, C. G.; Starzl, T. E.

    2010-01-01

    RÉSUMÉ L’élimination rénale des ions divalents, celle du Na et du K, ont été étudiées de façon comparative dans les suites immédiates de l’homotransplantation rénale chez 6 patients. Durant la période initiale polyurique (> 3ml/mn), le taux d’excrétion du Ca filtré (Cca/Ccr), du Mg, du P, du Na et du K, est élevé et il existe une corrélation étroite et quasi constante entre l’élimination du Ca, du Mg et du Na ; la corrélation n’est pas constante entre l’élimination du Na et du K, du Mg et du K. Pendant les deux jours suivants, le taux d’excrétion diminue, sauf pour le P ; il existe encore une corrélation entre l’excrétion du Ca, du Mg et du Na, non entre celle du Na et du K, du Mg et du K. L’excrétion du Ca l’emporte sur celle du Na au cours de la première période, non au cours de la seconde. A la lumière de ces données, on envisage l’intervention possible de divers facteurs, tels l’inflation hydrosique et l’hyperazotémie préalables, l’ischémie rénale contemporaine de la transplantation, les effets de la dénervation rénale, du traitement cortisonique, de l’hyperparathyroïdie et ceux des modifications circulatoires rénales. PMID:4574592

  9. Les effets des interfaces sur les proprietes magnetiques et de transport des multicouches nickel/iron et cobalt/silver

    NASA Astrophysics Data System (ADS)

    Veres, Teodor

    Cette these est consacree a l'etude de l'evolution structurale des proprietes magnetiques et de transport des multicouches Ni/Fe et nanostructures a base de Co et de l'Ag. Dans une premiere partie, essentiellement bibliographique, nous introduisons quelques concepts de base relies aux proprietes magnetiques et de transport des multicouches metalliques. Ensuite, nous presentons une breve description des methodes d'analyse des resultats. La deuxieme partie est consacree a l'etude des proprietes magnetiques et de transport des multicouches ferromagnetiques/ferromagnetiques Ni/Fe. Nous montrerons qu'une interpretation coherente de ces proprietes necessite la prise en consideration des effets des interfaces. Nous nous attacherons a mettre en evidence, a evaluer et a etudier les effets de ces interfaces ainsi que leur evolution, et ce, suite a des traitements thermiques tel que le depot a temperature elevee et l'irradiation ionique. Les analyses correlees de la structure et de la magnetoresistance nous permettront d'emettre des conclusions sur l'influence des couches tampons entre l'interface et le substrat ainsi qu'entre les couches elles-memes sur le comportement magnetique des couches F/F. La troisieme partie est consacree aux systemes a Magneto-Resistance Geante (MRG) a base de Co et Ag. Nous allons etudier l'evolution de la microstructure suite a l'irradiation avec des ions Si+ ayant une energie de 1 MeV, ainsi que les effets de ces changements sur le comportement magnetique. Cette partie debutera par l'analyse des proprietes d'une multicouche hybride, intermediaire entre les multicouches et les materiaux granulaires. Nous analyserons a l'aide des mesures de diffraction, de relaxation superparamagnetique et de magnetoresistance, les evolutions structurales produites par l'irradiation ionique. Nous etablirons des modeles qui nous aideront a interpreter les resultats pour une serie des multicouches qui couvrent un large eventail de differents comportements magnetiques

  10. AMPHOTERIC COLLOIDS : I. CHEMICAL INFLUENCE OF THE HYDROGEN ION CONCENTRATION.

    PubMed

    Loeb, J

    1918-09-20

    1. It has been shown in this paper that while non-ionized gelatin may exist in gelatin solutions on both sides of the isoelectric point (which lies for gelatin at a hydrogen ion concentration of C(H) = 2.10(-5) or pH = 4.7), gelatin, when it ionizes, can only exist as an anion on the less acid side of its isoelectric point (pH > 4.7), as a cation only on the more acid side of its isoelectric point (pH < 4.7). At the isoelectric point gelatin can dissociate practically neither as anion nor as cation. 2. When gelatin has been transformed into sodium gelatinate by treating it for some time with M/32 NaOH, and when it is subsequently treated with HCl, the gelatin shows on the more acid side of the isoelectric point effects of the acid treatment only; while the effects of the alkali treatment disappear completely, showing that the negative gelatin ions formed by the previous treatment with alkali can no longer exist in a solution with a pH < 4.7. When gelatin is first treated with acid and afterwards with alkali on the alkaline side of the isoelectric point only the effects of the alkali treatment are noticeable. 3. On the acid side of the isoelectric point amphoteric electrolytes can only combine with the anions of neutral salts, on the less acid side of their isoelectric point only with cations; and at the isoelectric point neither with the anion nor cation of a neutral salt. This harmonizes with the statement made in the first paragraph, and the experimental results on the effect of neutral salts on gelatin published in the writer's previous papers. 4. The reason for this influence of the hydrogen ion concentration on the stability of the two forms of ionization possible for an amphoteric electrolyte is at present unknown. We might think of the possibility of changes in the configuration or constitution of the gelatin molecule whereby ionized gelatin can exist only as an anion on the alkaline side and as a cation on the acid side of its isoelectric point. 5. The

  11. Influence of electron-ion collisions on Buneman instability

    NASA Astrophysics Data System (ADS)

    Rostomyan, Eduard

    2016-07-01

    Buneman instability (BI) [1] has been found to play a role in many scenarios in space physics and geophysics. It has also been invoked to explain many phenomena in the earth ionosphere [2] and in the solar chromosphere [3]. In double-layer and collisionless shock physics the same instability has been found responsible in formation of nonlinear structures [4]. In situations where an electron beam enters plasma, like in the fast ignition scenario for inertial fusion [5], Buneman modes are excited and play essential role [6]. BI is caused by motion of plasma electrons against ions. However, up to now investigations on BI did not take into account influence collisions in plasma (for quantum case a paper has recently appeared [7]). Influence of collisions may be very important especially in dense fully ionized plasma with long distance character of interaction. Particularly collisions lead to energy dissipation with an array of ensuing effects e.g. change of the instability physical nature to that of dissipative type [8]. Due to role of BI in various processes in space (and laboratory) plasma necessity of the consideration is long overdue. Absence of investigations on a problem along with its importance may be explained by its complexity only. For given case correct consideration should be based on solution of transport equation with collisional term. In fully ionized plasma correct description of collisions is given by Landau collision integral (LCI) [9]. This is very complex formation. It greatly complicates transport equation and actually makes it intractable. Since its formulation in 1936, there is very little literature on solution of the transport equation with LCI. Almost all successful attempts to accommodate influence of collisions on various processes in plasma are based on BGK model [10]. This model is much simpler. However in fully ionized plasma usage LCI is more appropriate as it is designed for system with long distance character of particle interaction

  12. Superstatistics analysis of the ion current distribution function: Met3PbCl influence study.

    PubMed

    Miśkiewicz, Janusz; Trela, Zenon; Przestalski, Stanisław; Karcz, Waldemar

    2010-09-01

    A novel analysis of ion current time series is proposed. It is shown that higher (second, third and fourth) statistical moments of the ion current probability distribution function (PDF) can yield new information about ion channel properties. The method is illustrated on a two-state model where the PDF of the compound states are given by normal distributions. The proposed method was applied to the analysis of the SV cation channels of vacuolar membrane of Beta vulgaris and the influence of trimethyllead chloride (Met(3)PbCl) on the ion current probability distribution. Ion currents were measured by patch-clamp technique. It was shown that Met(3)PbCl influences the variance of the open-state ion current but does not alter the PDF of the closed-state ion current. Incorporation of higher statistical moments into the standard investigation of ion channel properties is proposed. PMID:20354691

  13. Etude du mecanisme de predissociation de l'ion moleculaire de protoxyde d'azote par la mesure de l'energie cinetique des fragments de l'oxyde nitrique et de l'oxygene

    NASA Astrophysics Data System (ADS)

    Delisle, Claude

    La reaction N2 + O+ ↔ NO + + N, laquelle joue un role important dans la physique de la haute atmosphere, a ete le sujet de plusieurs etudes. Bien que cette reaction ait ete l'objet d'une quantite importante de travaux, ces derniers ne permettent toutefois pas de comprendre entierement le mecanisme d'un point de vue quantique, particulierement les niveaux d'energie excites des fragments qui permettent cette reaction. Puisque cette reaction n'est pas tres facile a reproduire en laboratoire, nous avons utilise la spectroscopie laser sur faisceaux d'ions rapides afin d'explorer les limites de dissociation de l'ion moleculaire intermediaire de cette reaction, a savoir l'ion N2O+. Le faisceau d'ions N2O+ rapides, apres excitation de l'ion moleculaire vers un niveau predissocie de l'etat A2Sigma+, se dissocie pour produire les fragments ioniques O+ et NO+. Par la mesure de la variation du nombre de fragments ioniques en fonction de l'energie cinetique des ions N2O+, nous avons enregistre les spectres de predissociation de l'ion N2O+. Lorsque c'etait possible, nous avons procede a l'analyse de ces spectres de dissociation afin d'en tirer les constantes moleculaires. Pour certaines des transitions rotationnelles intenses, nous avons mesure l'energie cinetique acquise par les fragments lors de la predissociation de l'ion N 2O+. Afin d'analyser les distributions en energie cinetique, nous avons developpe une simulation de l'experience en considerant, entre autres choses, la position des niveaux de vibration et de rotation des fragments diatomiques de chacune des limites de dissociation de N2O+. Les resultats de l'analyse sont exprimes en termes de population des niveaux de vibration des fragments diatomiques pour une distribution donnee de la population des niveaux de rotation des fragments. Les resultats ainsi obtenus, montrent que les fragments diatomiques sont produits dans des niveaux de vibration fortement excites. De tels niveaux d'excitation ne correspondent pas aux

  14. Influence of the quantum interference on the bosonic and fermionic ion-ion collisions

    NASA Astrophysics Data System (ADS)

    Hong, Woo-Pyo; Jung, Young-Dae

    2014-03-01

    The quantum interference effects on the bosonic-bosonic (He-4)-(He-4), fermionic-fermionic (He-3)-(He-3), and bosonic-fermionic (He-4)-(He-3) ion-ion collisions are investigated by using the isotope of the He nucleus in dense semiclassical Coulomb systems with the Faxen-Holtzmark method. It is found that the scattering cross section for the fermionic-fermionic ion-ion collision is greater than the bosonic-bosonic and bosonic-fermionic ion collision cross sections. It is also found that the collisional induced quantum interference effect enhances the ion-ion collision cross section in semiclassical Coulomb systems. The variation of the quantum-mechanical effect on the bosonic and fermionic ion-ion collisions is also discussed. This paper is dedicated to the late Prof. P. K. Shukla in memory of exciting and stimulating collaborations on physical processes in semiclassical Coulomb systems.

  15. Influence of ion beam energy on SEGR failure thresholds of vertical power MOSFETs

    SciTech Connect

    Titus, J.L.; Wheatley, C.F.; Allenspach, M.; Schrimpf, R.D.; Brews, J.R.; Galloway, K.F.; Burton, D.I.; Pease, R.L.

    1996-12-01

    For the first time, experimental observations and numerical simulations show that the impact energy of the test ion influences the single-event gate rupture (SEGR) failure thresholds of vertical power MOSFETs. Current testing methodology may produce false hardness assurance.

  16. Motion of ions influenced by enhanced Alfven waves

    SciTech Connect

    Wu, C.S.; Yoon, P.H.; Chao, J.K.

    1997-03-01

    In this paper we discuss the dynamics of an ion interacting with large-amplitude Alfven waves. The objective of the present analysis is to attain an in-depth understanding of the ion-pickup process which has been extensively studied in the literature by means of both quasilinear theory and numerical simulations. In general, results from self-consistent simulations provide a more complete picture of the ion pickup process, but details of the pickup process are not easily comprehended on the basis of these results. For this reason, the present study is carried out in which a test particle approach is used. It is found that for moderately large-amplitude Alfven waves, an approximate analytical solution for the ion equation of motion can be obtained. This solution clarifies a number of basic issues such as (1) whether the cyclotron resonance is a necessary condition for the pickup to occur, (2) what is the role of initial ion phase space position on subsequent pitch angle scattering, and (3) how the wave amplitude affects the maximum velocity that an ion can gain along the direction of the ambient magnetic field during the pickup process. {copyright} {ital 1997 American Institute of Physics.}

  17. Influence of hard water ions on the growth rate of Salmonella Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The influence of magnesium and calcium ions in process water on the growth of Salmonella typhimurium was evaluated to address the concerns for food quality and safety. Salmonella typhimurium was exposed to media containing 500 ppm and 1000 ppm of magnesium and calcium ions for 45 minutes followed by...

  18. Influence of hard water ions on the growth of salmonella in poultry processing water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The influence of magnesium and calcium ions in process water on the growth of Salmonella was evaluated and related to the contamination in process wastewater. Salmonella typhimurium was grown in the laboratory and exposed to 500 mg/kg and 1000 mg/kg of magnesium and calcium ions to simulate hard pr...

  19. Etude des mecanismes de transport des ions chlore dans le beton en vue de la mise au point d'un essai de migration

    NASA Astrophysics Data System (ADS)

    Arsenault, Julie

    The main purpose of this research was to propose a reliable migration test to predict the chloride diffusivity of cement based materials. In this research we also studied the interaction phenomena between chloride and hydrated cement paste in order to improve our knowledge of these mechanisms. The first results of this research program showed that both chloride concentration and the composition of solutions used in the migration test may affect the chloride transport, if the equation used to calculate the diffusion coefficient does not describe correctly the transport in the migration experiment. Some tests were also conducted to characterise the microstructure of cement pastes. Results of these tests showed that neither the electrical field for a DC potential of 10 volts, nor the pure diffusion for chloride concentrations below 1,5 mol/L, do affect significantly the microstructure of cement pastes. Various w/c ratios and types of cement were also tested in this research program. Results showed that both characteristics influence the chloride transport in concrete, whether the diffusivity is calculated from the diffusion or the migration test. Results of migration and diffusion experiments showed that all ions present in the system, not only the chloride, can move under the chemical and/or electrical potential, then affecting the chloride transport into concrete. In addition, we studied interactions between chloride and cement paste by means of an immersion test. We thereby observed that some characteristics, such as the type of solution used in the immersion test, the total aluminate content of cement and the age of the material tested, do influence the chloride binding capacity of the cement paste. We also observed an acceleration of the lixiviation phenomena and significant production of ettringite. In concluding, we proposed a new method to measure the chloride binding capacity of cement paste, using samples previously tested by the migration test. Results

  20. Ion adsorption and its influence on direct current electric field induced deformations of flexoelectric nematic layers

    NASA Astrophysics Data System (ADS)

    Derfel, Grzegorz; Buczkowska, Mariola

    2011-07-01

    The influence of ion adsorption on the behavior of the nematic liquid crystal layers is studied numerically. The homeotropic flexoelectric layer subjected to the dc electric field is considered. Selective adsorption of positive ions is assumed. The analysis is based on the free energy formalism for ion adsorption. The distributions of director orientation angle, electric potential, and ion concentrations are calculated by numerical resolving of suitable torques equations and Poisson equation. The threshold voltages for the deformations are also determined. It was shown that adsorption affects the distributions of both cations and anions. Sufficiently large number of adsorbed ions leads to spontaneous deformation arising without any threshold if the total number of ions creates sufficiently strong electric field with significant field gradients in the neighborhood of electrodes. The spontaneous deformations are favored by strong flexoelectricity, large thickness, large ion concentrations, weak anchoring, and large adsorption energy.

  1. Investigation of Scrambled Ions in Tandem Mass Spectra, Part 2. On the Influence of the Ions on Peptide Identification

    NASA Astrophysics Data System (ADS)

    Dong, Nai-ping; Liang, Yi-zeng; Yi, Lun-zhao; Lu, Hong-mei

    2013-06-01

    A comprehensive investigation was performed to understand the influence of sequence scrambling in peptide ions on peptide identification results. To achieve this, four tandem mass spectrometry datasets with scrambled ions included and with them excluded were analyzed by Crux, X!Tandem, SpectraST, Lutefisk, and PepNovo. While the different algorithms differed in their performance, an increase in the number of correctly identified peptides was generally observed when removing scrambled ions, with the exception of the SpectraST algorithm. However, the variation of the match scores upon removal was unpredictable. Following these investigations, an interpretation was given on how the scrambled ions affect peptide identification. Lastly, a simulated theoretical mass spectral library derived from the NIST peptide Libraries was constructed and searched by SpectraST to study whether scrambled ions in predicted mass spectra could affect peptide identification. Consistent with the peptide library search results, no significant variations for dot product scores as well as peptide identification results were observed when these ions were included in the theoretical MS/MS spectra. From the five adopted algorithms, the SpectraST and Crux provided the most robust results, whereas X!Tandem, PepNovo, and Lutefisk were sensitive to the existence of the scrambled ions, especially the latter two de novo sequencing algorithms.

  2. Influence of discharge gap on the discharge stability in a short vacuum arc ion source

    SciTech Connect

    Chen, L.; Zhang, G. L.; Jin, D. Z.; Dai, J. Y.; Yang, L.

    2012-02-15

    The influence of the discharge gap between cathode and anode on the discharge stability in a short vacuum arc (SVA) ion source is presented in this paper. Planar cathode and cylindrical hollow anode made of titanium are investigated. There is a great need in present accelerator injection research for SVA source to produce the small deviation of the ion current beam. Current research shows that increasing the short discharge gap can reduce the level of ion current deviation and ion charge deviation from 29% and 31% to 15% and 17%, respectively. A microplasma plume generation mechanism in SVA and scanning electron microscopic results can be used to explain this interesting phenomenon.

  3. Metal ion influence on eumelanin fluorescence and structure

    NASA Astrophysics Data System (ADS)

    Sutter, Jens-Uwe; Birch, David J. S.

    2014-06-01

    Melanin has long been thought to have an unworkably weak and complex fluorescence, but here we study its intrinsic fluorescence in order to demonstrate how metal ions can be used to control the rate of formation, constituents and structure of eumelanin formed from the well-known laboratory auto-oxidation of 3,4-dihydroxy-L-phenylalanine (L-DOPA). The effect on eumelanin absorption and fluorescence of a range of solvated metal ions is reported including Cu, Zn, Ni, Na and K. Monovalent cations and Zn have little effect, but the effect of transition metal cations can be considerable. For example, at pH 10, copper ions are shown to accelerate the onset of eumelanin formation, but not the rate of formation once it commences, and simplify the usual complex structure and intrinsic fluorescence of eumelanin in a way that is consistent with an increased abundance of 5,5-dihydroxyindole-2-carboxylic acid (DHICA). The presence of a dominant 6 ns fluorescence decay time at 480 nm, when excited at 450 nm describes a distinct photophysical species, which we tentatively assign to small oligomers. Copper is well-known to normally quench fluorescence, but increasing amounts of copper surprisingly leads to an increase in the fluorescence decay time of eumelanin, while reducing the fluorescence intensity, suggesting copper modification of the excited state. Such results have bearing on diverse areas. The most accepted morphology for melanin is that of a graphite-like sheet structure, and one which readily binds metal ions, an interaction that is thought to have an important, though as yet unclear bearing on several areas of medicine including neurology. There is also increasing interest in bio-mimicry by preparing and labelling sheet structures with metal ions for new electronic and photonic materials.

  4. DNA fragmentation induced by fe ions in human cells: shielding influence on spatially correlated damage

    SciTech Connect

    Antonelli, F.; Belli, M.; Campa, A.; Chatterjee, A.; Dini, V.; Esposito, G.; Rydberg, B.; Simone, G.; Tabocchini, M.A.

    2003-11-19

    Outside the magnetic field of the Earth, high energy heavy ions constitute a relevant part of the biologically significant dose to astronauts during the very long travels through space. The typical pattern of energy deposition in the matter by heavy ions on the microscopic scale is believed to produce spatially correlated damage in the DNA which is critical for radiobiological effects. We have investigated the influence of a lucite shielding on the initial production of very small DNA fragments in human fibroblasts irradiated with 1 GeV/u iron (Fe) ions. We also used small gamma, Greek-rays as reference radiation. Our results show: (1) a lower effect per incident ion when the shielding is used; (2) an higher DNA Double Strand Breaks (DSB) induction by Fe ions than by small gamma, Greek-rays in the size range 123 kbp; (3) a non-random DNA DSB induction by Fe ions.

  5. Influence of ion assistance on LaF3 films deposited by molybdenum boat evaporation.

    PubMed

    Liu, Ming-Chung; Lee, Cheng-Chung; Kaneko, Masaaki; Nakahira, Kazuhide; Takano, Yuuichi

    2012-05-20

    LaF3 thin films at 193 nm were deposited by the molybdenum boat evaporation with ion-assisted deposition (IAD). Various optical characteristics, stress, and microstructures that formed under different ion-beam voltages of IAD deposition were investigated. The relation between these properties is also discussed. LaF3 films deposited with IAD exhibited small rough surfaces and large optical loss at 193 nm. The largest value of optical loss for films at 193 nm, which were prepared at an ion-beam voltage of 400 V, was 1.55% and the extinction coefficient was smaller than 0.0015. Microstructures and crystalline structures of films were influenced and changed by the ion-assisted deposition process. Tensile stress value of films increased as the ion-beam voltage rose. Refractive index, related to the packing density and microstructures, also increased as the ion-beam voltage rose. PMID:22614587

  6. Influence of surface oxidation on ion dynamics and capacitance in porous and nonporous carbon electrodes

    DOE PAGESBeta

    Dyatkin, Boris; Zhang, Yu; Mamontov, Eugene; Kolesnikov, Alexander I.; Cheng, Yongqiang; Meyer, III, Harry M.; Cummings, Peter T.; Gogotsi, Yury G.

    2016-04-07

    Here, we investigate the influence of surface chemistry and ion confinement on capacitance and electrosorption dynamics of room-temperature ionic liquids (RTILs) in supercapacitors. Using air oxidation and vacuum annealing, we produced defunctionalized and oxygen-rich surfaces of carbide-derived carbons (CDCs) and graphene nanoplatelets (GNPs). While oxidized surfaces of porous CDCs improve capacitance and rate handling abilities of ions, defunctionalized nonporous GNPs improve charge storage densities on planar electrodes. Quasi-elastic neutron scattering (QENS) and inelastic neutron scattering (INS) probed the structure, dynamics, and orientation of RTIL ions confined in divergently functionalized pores. Oxidized, ionophilic surfaces draw ions closer to pore surfaces andmore » enhance potential-driven ion transport during electrosorption. Molecular dynamics (MD) simulations corroborated experimental data and demonstrated the significance of surface functional groups on ion orientations, accumulation densities, and capacitance.« less

  7. DNA fragmentation induced by Fe ions in human cells: shielding influence on spatially correlated damage

    NASA Technical Reports Server (NTRS)

    Antonelli, F.; Belli, M.; Campa, A.; Chatterjee, A.; Dini, V.; Esposito, G.; Rydberg, B.; Simone, G.; Tabocchini, M. A.

    2004-01-01

    Outside the magnetic field of the Earth, high energy heavy ions constitute a relevant part of the biologically significant dose to astronauts during the very long travels through space. The typical pattern of energy deposition in the matter by heavy ions on the microscopic scale is believed to produce spatially correlated damage in the DNA which is critical for radiobiological effects. We have investigated the influence of a lucite shielding on the initial production of very small DNA fragments in human fibroblasts irradiated with 1 GeV/u iron (Fe) ions. We also used gamma rays as reference radiation. Our results show: (1) a lower effect per incident ion when the shielding is used; (2) an higher DNA Double Strand Breaks (DSB) induction by Fe ions than by gamma rays in the size range 1-23 kbp; (3) a non-random DNA DSB induction by Fe ions. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

  8. Sputtering at grazing ion incidence: Influence of adatom islands

    SciTech Connect

    Rosandi, Yudi; Redinger, Alex; Michely, Thomas; Urbassek, Herbert M.

    2010-09-15

    When energetic ions impinge at grazing incidence onto an atomically flat terrace, they will not sputter. However, when adatom islands (containing N atoms) are deposited on the surface, they induce sputtering. We investigate this effect for the specific case of 83 deg. -incident 5 keV Ar ions on a Pt (111) surface by means of molecular-dynamics simulation and experiment. We find that - for constant coverage {Theta} - the sputter yield has a maximum at island sizes of N congruent with 10-20. A detailed picture explaining the decline of the sputter yield toward larger and smaller island sizes is worked out. Our simulation results are compared with dedicated sputtering experiments, in which a coverage of {Theta}=0.09 of Pt adatoms are deposited onto the Pt (111) surface and form islands with a broad distribution around a most probable size of N congruent with 20.

  9. Ion-specific effects influencing the dissolution of tricalcium silicate

    SciTech Connect

    Nicoleau, L.; Schreiner, E.; Nonat, A.

    2014-05-01

    It has been recently demonstrated that the dissolution kinetics of tricalcium silicate (C{sub 3}S) is driven by the deviation from its solubility equilibrium. In this article, special attention is paid to ions relevant in cement chemistry likely to interact with C{sub 3}S. In order to determine whether specific effects occur at the interface C{sub 3}S–water, particular efforts have been made to model ion activities using Pitzer's model. It has been found that monovalent cations and monovalent anions interact very little with the surface of C{sub 3}S. On the other side, divalent anions like sulfate slow down the dissolution more strongly by modifying the surface charging of C{sub 3}S. Third, aluminate ions covalently bind to surface silicate monomers and inhibit the dissolution in mildly alkaline conditions. The formation and the breaking of these bonds depend on pH and on [Ca{sup 2+}]. Thermodynamic calculations performed using DFT combined with the COSMO-RS solvation method support the experimental findings.

  10. Influence of metal ions on the interaction between gatifloxacin and calf thymus DNA

    NASA Astrophysics Data System (ADS)

    Yuan, Xiao-ying; Qin, Jun; Lu, Ling-ling

    2010-02-01

    To study the interaction between gatifloxacin (GT), metal ions (Cu 2+, Cd 2+, Co 2+, Mg 2+) and calf thymus DNA under condition of physiology pH, UV absorption and fluorescence methods were adopted. Result shows that metal ions and DNA are able to react with GT in ground state. In further research, by studying the influence of metal ions on binding of GT with DNA in metal ions-GT-DNA ternary system, we found that influential mechanism of Mg 2+ on the binding of GT with DNA may be different from the other three. Mg 2+ can act as a bridge in the binding of GT's carboxyl/carbonyl with DNA phosphate in certain concentration range; while Cu 2+, Cd 2+, Co 2+ can combine directly with GT by reaction between GT carboxyl/carbonyl and DNA base, and enhance the binding ability of GT with DNA. The influence extent and type depend not only on the binding site of DNA with metal ions (phosphate or base), but also the binding ability of which. The stronger the binding ability of metal ions with DNA base is, the larger their promotion to binding of GT with DNA is. The order of metal ions' influential ability on the binding of GT-DNA is identical to the binding ability order of metal ions with DNA base, that is: Cu 2+ > Cd 2+ > Co 2+ > Mg 2+.

  11. The influence of dust particles on electromagnetic ion cyclotron waves in a bi-Lorentzian plasma

    SciTech Connect

    Venugopal, C.; Varughese, J.K.; Antony, S.; Anilkumar, C.P.; Renuka, G.

    1997-10-01

    The influence of dust particles on electromagnetic ion cyclotron (EMIC) waves, propagating parallel to the magnetic field, in a plasma where the hot ions are modelled by a bi-Lorentzian or Kappa distribution has been studied. The electrons and dust particles have been treated as cold. Expressions for the dispersion relations and growth/damping rates in both high- and low-{beta} plasmas have been derived. For the low-{beta} case temperature anisotropy is the source of instability in an electron{endash}ion plasma. This instability is strongly influenced by the temperature anisotropy of the hot ions and the charge and density of the dust particles; the instability increases with these parameters. However, in high-{beta} plasmas, the instability is driven by the dust. The growth rate increases with the charge on the dust; but with increasing dust densities the EMIC wave propagates almost freely. {copyright} {ital 1997 American Institute of Physics.}

  12. The influence of lipids on voltage-gated ion channels

    PubMed Central

    Jiang, Qiu-Xing; Gonen, Tamir

    2012-01-01

    Voltage-gated ion channels are responsible for transmitting electrochemical signals in both excitable and non-excitable cells. Structural studies of voltage-gated potassium and sodium channels by X-ray crystallography have revealed atomic details on their voltage-sensor domains and pore domains, and were put in context of disparate mechanistic views on the voltage-driven conformational changes in these proteins. Functional investigation of voltage-gated channels in membranes, however, showcased a mechanism of lipid-dependent gating for voltage-gated channels, suggesting that the lipids play an indispensible and critical role in the proper gating of many of these channels. Structure determination of membrane-embedded voltage-gated ion channels appears to be the next frontier in fully addressing the mechanism by which the voltage sensor domains control channel opening. Currently electron crystallography is the only structural biology method in which a membrane protein of interest is crystallized within a complete lipid-bilayer mimicking the native environment of a biological membrane. At a sufficiently high resolution, an electron crystallographic structure could reveal lipids, the channel and their mutual interactions at the atomic level. Electron crystallography is therefore a promising avenue toward understanding how lipids modulate channel activation through close association with the voltage sensor domains. PMID:22483432

  13. Influence of multiple ion species on low-frequency electromagnetic wave instabilities. [in solar wind

    NASA Technical Reports Server (NTRS)

    Brinca, Armando L.; Tsurutani, Bruce T.

    1989-01-01

    The effect of multiple (singly ionized) coexisting newborn ion species on the stability of low-frequency electromagnetic waves was investigated using a plasma model in which solar wind magnetoplasma is made up of isotropic Maxwellian electron and proton populations with a common number density of 4.95/cu cm and temperatures equal to 17.2 eV and 6.9 eV, respectively. It is shown that the effect of multiple ions on wave growth, for given background magnetoplasma conditions and relative densities, depends not only on their mass but also on the physical nature of the wave modes. If the ion masses are disparate, each one of the coexisting ion beams tends to stimulate instabilities without undue influence from the other species. If the masses of newborn ions are similar, they can strongly catalyze wave growth of fluidlike nonresonant modes, but bring about weak growth enhancements in cyclotron resonant instabilities.

  14. Influence of finite radial geometry on the growth rate of ion-channel free electron laser

    SciTech Connect

    Bahmani, Mohammad; Hamzehpour, Hossein; Hasanbeigi, Ali

    2013-11-15

    The influence of finite radial geometry on the instability of a tenuous relativistic electron beam propagating in an ion-channel in a waveguide is investigated. The instability analysis is based on the linearized Vlasov-Maxwell equations for the perturbation about a self-consistent beam equilibrium. With the help of characteristic method the dispersion relation for the TE-mode is derived and analyzed through the numerical solutions. It is found that the positioning of the beam radius R{sub b} relative to the waveguide radius R{sub c}, and the ion-channel frequency can have a large influence on the maximum growth rate and corresponding wave number.

  15. The influence of silver-ion doping using ion implantation on the luminescence properties of Er-Yb silicate glasses

    NASA Astrophysics Data System (ADS)

    Stanek, S.; Nekvindova, P.; Svecova, B.; Vytykacova, S.; Mika, M.; Oswald, J.; Mackova, A.; Malinsky, P.; Spirkova, J.

    2016-03-01

    A set of zinc-silicate glasses with different ratios of erbium and ytterbium was fabricated. To achieve Ag-rich thin films in a sub-surface layer, ion-implantation technique at an energy of 1.2 MeV and 1.7 MeV with a fluence of 1 × 1016 cm-2 was used. Post-implantation annealing was also applied. Changes in the spectroscopic and lasing properties of erbium ions as a function of implantation fluence of silver were studied with the aim to assess the positive effect of silver as a sensitiser of erbium luminescence. Therefore, absorption spectra in the visible range as well as luminescence spectra in the near-infrared range were measured and partially also the 4I11/2-4I15/2 transition of the erbium ion was studied. The results showed that silver positively influenced luminescence intensity at 1530 nm by increasing it almost three times. The biggest increase was achieved in glass with the highest concentration of erbium. Luminescence lifetime was not significantly influenced by the presence of silver and still remained around 10 ms.

  16. Influence of Inorganic Ions on Aggregation and Adsorption Behaviors of Human Adenovirus

    EPA Science Inventory

    In this study, we investigated the influence of inorganic ions on the aggregation and deposition (adsorption) behavior of human adenovirus (HAdV). Experiments were conducted to determine the surface charge and size of HAdV and viral adsorption capacity of sand in different salt c...

  17. Influence des brandons sur la propagation d'un feu de forêt

    NASA Astrophysics Data System (ADS)

    Porterie, Bernard; Zekri, Nouredine; Clerc, Jean-Pierre; Loraud, Jean-Claude

    2005-12-01

    A two-dimensional weighed-site small-world network is proposed to study the action of firebrands (lofted flaming or glowing debris) on fire spread through homogeneous or heterogeneous systems. The firebrand emission distance obeys an exponentially-decreasing distribution law. For homogeneous systems, the effect of firebrands is strengthened when the fire impact length decreases and the characteristic firebrand emission distance increases. As a result, jumps in the rate of spread appear and time oscillations in the burning area can occur. For heterogeneous systems, this effect becomes weaker as the degree of disorder and the distance of firebrand emission increase. The influence of characteristic lengths of radiation, firebrand emission, and medium heterogeneity on fire spread is discussed. To cite this article: B. Porterie et al., C. R. Physique 6 (2005).

  18. Influence of Cu ion implantation on the microstructure and cathodoluminescence of ZnS nanostructures

    NASA Astrophysics Data System (ADS)

    Shang, L. Y.; Zhang, D.; Liu, B. Y.

    2016-07-01

    The microstructure and optical properties of as-synthesized and Cu ion implanted ZnS nanostructures with branched edges are studied by using high-resolution transmission electron microscope (TEM) and spatially-resolved cathodoluminescence measurement. Obvious crystalline deterioration has been observed in Cu-doped ZnS nanostructures due to the invasion of Cu ions into ZnS lattice. It was found that the optical emissions of ZnS nanostructures can be selectively modified through the control of Cu ion dose and subsequent heat treatment. An increase of Cu dopant content will lead to an apparent red-shift of the intrinsic band-gap emission in the UV range and the broadening of defect-related emission in visible range. The influences of Cu ion implantation on the microstructure and related optical properties were discussed.

  19. Influence of ion movement in a particle trap on the bound electron g factor

    NASA Astrophysics Data System (ADS)

    Michel, Niklas; Zatorski, Jacek; Keitel, Christoph H.

    2015-11-01

    In the relativistic description of atomic systems in external fields, the total momentum and the external electric field couple to the angular momentum of the individual particles. Therefore, the motional state of an ion in a particle trap influences measurements of internal observables such as energy levels or the g factor. We calculate the resulting relativistic shift of the Larmor frequency and the corresponding g -factor correction for a bound electron in a hydrogenlike ion in the 1 S state due to the ion moving in a Penning trap and show that it is negligible at the current precision of measurements. We also show that the analogous energy shift for measurements with an ion in the ground state of a Paul trap vanishes in leading order.

  20. The influence of fluoride ions on the equilibrium between titanium ions and titanium metal in fused alkali chloride melts.

    PubMed

    Song, Jianxun; Wang, Qiuyu; Wu, Jinyu; Jiao, Shuqiang; Zhu, Hongmin

    2016-08-15

    KF is employed as a source of fluoride ions added to the melt to disclose the influence of fluoride on the disproportionation reactions of titanium ions, 3Ti(2+) = 2Ti(3+) + Ti, and 4Ti(3+) = 3Ti(4+) + Ti. The results reveal that the equilibrium transferred to the right direction for the first reaction and the apparent equilibrium constant increased sharply, mainly because of the formation of coordination compounds: TiFi(3-i). The accurate values of the equilibrium constants referring to the formation reactions of Ti(3+) + iF(-) = TiFi(3-i) (i = 1-6) in NaCl-KCl melt at 1023 K were evaluated with a best fit least squares method. It is also revealed that the stable states of the coordination compounds are TiF(2+), TiF2(+), TiF4(-) and TiF6(3-). Moreover, the Gibbs free energies for complex formation were estimated. Ti(2+) was undetectable when the concentration of fluoride ion was high enough. The equilibrium constant for the formation reaction, Ti(4-) + 6F(-) = TiF6(2-), was evaluated. The equilibrium constant, Kc2, for the disproportionation reaction 4Ti(3+) = 3Ti(4+) + Ti, in chloride melt was determined as 0.015. PMID:27212433

  1. Influence of aggressive ions on the degradation behavior of biomedical magnesium alloy in physiological environment.

    PubMed

    Xin, Yunchang; Huo, Kaifu; Tao, Hu; Tang, Guoyi; Chu, Paul K

    2008-11-01

    Various electrochemical approaches, including potentiodynamic polarization, open circuit potential evolution and electrochemical impedance spectroscopy (EIS), are employed to investigate the degradation behavior of biomedical magnesium alloy under the influence of aggressive ions, such as chloride, phosphate, carbonate and sulfate, in a physiological environment. The synergetic effects and mutual influence of these ions on the degradation behavior of Mg are revealed. Our results demonstrate that chloride ions can induce porous pitting corrosion. In the presence of phosphates, the corrosion rate decreases and the formation of pitting corrosion is significantly delayed due to precipitation of magnesium phosphate. Hydrogen carbonate ions are observed to stimulate the corrosion of magnesium alloy during the early immersion stage but they can also induce rapid passivation on the surface. This surface passivation behavior mainly results from the fast precipitation of magnesium carbonate in the corrosion product layer that can subsequently inhibit pitting corrosion completely. Sulfate ions are also found to stimulate magnesium dissolution. These results improve our understanding on the degradation mechanism of surgical magnesium in the physiological environment. PMID:18571486

  2. The Influence of Iron on Ammonium Ion Generation from Nitrate Ion in Liquid Phase

    NASA Astrophysics Data System (ADS)

    Youhei, Kinoshita; Naoki, Okumura; Kazunori, Takashima; Shinji, Katsura; Akira, Mizuno

    2005-02-01

    Flue gas cleaning in discharge plasma process has been studied intensively and we have tried to remove the NOx and SO2 using the wet-type plasma reactor. In this system, NO is oxidized to NO2 and absorbed as NO3-, and SO2 is absorbed as SO32- and oxidized in the liquid to SO42-. But the concentration of NO3- was saturated and the absorption of NOx and SO2 was inhibited. Then, the reduction of NO3- in the liquid is required. We examined the reductive reaction of NO3- to NH4+ using discharge above the liquid surface then the pH value of the liquid was changed to alkaline slightly. When the Fe plate was used as a ground electrode in the liquid, NH4+ was generated. Then, the relation between the generation of NH4+ and Fe ions (Fe2+ and Fe3+) was studied. When Fe2+ was presented in the liquid, NH4+ was generated and Fe2+ was oxidized to Fe3+. Fe2+ is required to generate NH4+ from NO3-. When NH4+ was generated from NO3-, both the calculated pH value from NH4+ concentration and the measured pH value indicated a similar value. From these results, the discharge above the liquid surface was effective to convert NO3- to NH4+ and the reductive reaction leads to more absorption of NO3-. These results showed that the wet-type plasma reactor is effective for NOx and SO2 removal system.

  3. ECR Nb Films Grown on Amorphous and Crystalline Cu Substrates: Influence of Ion Energy

    SciTech Connect

    Valente, Anne-Marie; Eremeev, Grigory V.; Spradlin, Joshua K.; Phillips, H. Lawrence; Reece, Charles E.; Cao, C.; Proslier, Thomas; Tao, T.

    2014-02-01

    In the pursuit of niobium (Nb) films with similar performance with the commonly used bulk Nb surfaces for Superconducting RF (SRF) applications, significant progress has been made with the development of energetic condensation deposition techniques. Using energetic condensation of ions extracted from plasma generated by Electron Cyclotron Resonance, it has been demonstrated that Nb films with good structural properties and RRR comparable to bulk values can be produced on metallic substrates. The controlled incoming ion energy enables a number of processes such as desorption of adsorbed species, enhanced mobility of surface atoms and sub-implantation of impinging ions, thus producing improved film structures at lower process temperatures. Particular attention is given to the nucleation conditions to create a favourable template for growing the final surface exposed to SRF fields. The influence of the deposition energy on film growth on copper substrates is investigated with the characterization of the film surface, structure, superconducting properties and RF performance.

  4. Influence of bicarbonate ions on the deterioration of mortar bars in sulfate solutions

    SciTech Connect

    Kunther, W.; Lothenbach, B.; Scrivener, K.

    2013-02-15

    This work investigates the influence of bicarbonate ions on the deterioration of cementitious material exposed to sulfate ions. Mortars based on a CEM I and on a CEM III/B cement were investigated. Experimental investigations were compared to thermodynamic modeling and phase characterization to understand the differences in deterioration. The presence of bicarbonate ions significantly reduced the expansion of the CEM I mortars. Thermodynamic modeling showed that at high concentrations of bicarbonate ettringite and gypsum become unstable. Microstructural characterization combined with information from thermodynamic modeling suggests that conditions of high supersaturation with respect to ettringite are unlikely in the samples exposed in solutions containing bicarbonate. Consequently, expansive forces are not generated by the crystallization pressure of ettringite. There was little expansion of the CEM III/B sample even in the sodium sulfate solution. In the bicarbonate solution this mortar showed a highly leached zone at the surface in which calcite was observed.

  5. The influence of the ion polarization current on magnetic island stability in a tokamak plasma

    SciTech Connect

    Fitzpatrick, R.; Waelbroeck, F. L.; Militello, F.

    2006-12-15

    The influence of the ion polarization current on the stability of a constant-{psi} magnetic island in a tokamak plasma is investigated numerically using a reduced two-fluid model in two-dimensional slab geometry. The polarization current is found to be negligibly small when the island is either too narrow or too wide. However, under certain circumstances, there exists an intermediate regime in which the polarization current is appreciable, and has a stabilizing influence on the island. This effect may account for the metastable nature of neoclassical tearing modes in tokamak plasmas.

  6. The Influence of Spatial Variations of Diffusion Length on Charge Collected by Diffusion from Ion Tracks

    NASA Technical Reports Server (NTRS)

    Edmonds, L. D.

    1996-01-01

    Charge collected by diffusion from ion tracks in a semiconductor substrate may be influenced by the substrate diffusion length, which is related to recombination losses. A theoretical analysis shows that, excluding some extreme cases, charge collection is insensitive to spatial variations in the diffusion length funciton, so it is possible to define an effective diffusion length having the property that collected charge can be approximated by assuming a uniform diffusion length equal to this effective value.

  7. Influence of irradiation spectrum and implanted ions on the amorphization of ceramics

    SciTech Connect

    Zinkle, S.J.; Snead, L.L.

    1995-12-31

    Polycrystalline Al2O3, magnesium aluminate spinel (MgAl2O4), MgO, Si3N4, and SiC were irradiated with various ions at 200-450 K, and microstructures were examined following irradiation using cross-section TEM. Amorphization was not observed in any of the irradiated oxide ceramics, despsite damage energy densities up to {similar_to}7 keV/atom (70 displacements per atom). On the other hand, SiC readily amorphized after damage levels of {similar_to}0.4 dpa at room temperature (RT). Si3N4 exhibited intermediate behavior; irradiation with Fe{sup 2+} ions at RT produced amorphization in the implanted ion region after damage levels of {similar_to}1 dpa. However, irradiated regions outside the implanted ion region did not amorphize even after damage levels > 5 dpa. The amorphous layer in the Fe-implanted region of Si3N4 did not appear if the specimen was simultaneoulsy irradiated with 1-MeV He{sup +} ions at RT. By comparison with published results, it is concluded that the implantation of certain chemical species has a pronounced effect on the amorphization threshold dose of all five materials. Intense ionizing radiation inhibits amorphization in Si3N4, but does not appear to significantly influence the amorphization of SiC.

  8. Removal of nitrate ions from water by activated carbons (ACs)—Influence of surface chemistry of ACs and coexisting chloride and sulfate ions

    NASA Astrophysics Data System (ADS)

    Ota, Kazunari; Amano, Yoshimasa; Aikawa, Masami; Machida, Motoi

    2013-07-01

    Adsorptive removal of nitrate ions in aqueous solution using activated carbons (ACs) was examined. After ash was removed from Filtrasorb 400 AC, oxidation and outgassing and several heat treatments were carried out to modify the textural and surface properties of ACs. AC oxidized with 8 M nitric acid followed by outgassing at 900 °C (Ox-9OG) exhibited the greatest Langmuir adsorption capacity and affinity for nitrate removal among the total 7 ACs examined. Influence of coexisting chloride and sulfate ions was investigated as well to inspect the nitrate adsorption sites. The highest amount of sites which adsorbed nitrate ions exclusively could be observed for Ox-9OG adsorbent even though as great as 250 times greater number of chloride or sulfate ions over nitrate ions were present in the same aqueous system. Some basic oxygen species on carbon were estimated to work as selective adsorption sites for nitrate ions.

  9. Influence of Xe{sub 2}{sup +} ions on the micro-hollow cathode discharge driven by thermionic emission

    SciTech Connect

    Levko, D.; Bliokh, Y. P.; Krasik, Ya. E.

    2014-04-15

    The influence of Xe{sub 2}{sup +} dimer ions and excited Xe* atoms on the hollow cathode discharge driven by electron thermionic emission is studied using two-dimensional Particle-in-Cell Monte Carlo Collisions modeling. A comparison with the results of two-component (electrons and Xe{sup +} ions) plasma modeling showed that the presence of the Xe{sub 2}{sup +} dimer ions and excited Xe* atoms in the plasma affects the plasma parameters (density, potential, and ion fluxes toward the cathode). The influence of Xe{sub 2}{sup +} ions and Xe* atoms on the plasma sheath parameters, such as thickness and the ion velocity at the sheath edge, is analyzed.

  10. Influence of nuclear interactions in polyethylene range compensators for carbon-ion radiotherapy

    SciTech Connect

    Kanematsu, Nobuyuki Koba, Yusuke; Ogata, Risa; Himukai, Takeshi

    2014-07-15

    Purpose: A recent study revealed that polyethylene (PE) would cause extra carbon-ion attenuation per range shift by 0.45%/cm due to compositional differences in nuclear interactions. The present study aims to assess the influence of PE range compensators on tumor dose in carbon-ion radiotherapy. Methods: Carbon-ion radiation was modeled to be composed of primary carbon ions and secondary particles, for each of which the dose and the relative biological effectiveness (RBE) were estimated at a tumor depth in the middle of spread-out Bragg peak. Assuming exponential behavior for attenuation and yield of these components with depth, the PE effect on dose was calculated for clinical carbon-ion beams and was partly tested by experiment. The two-component model was integrated into a treatment-planning system and the PE effect was estimated in two clinical cases. Results: The attenuation per range shift by PE was 0.1%–0.3%/cm in dose and 0.2%–0.4%/cm in RBE-weighted dose, depending on energy and range-modulation width. This translates into reduction of RBE-weighted dose by up to 3% in extreme cases. In the treatment-planning study, however, the effect on RBE-weighted dose to tumor was typically within 1% reduction. Conclusions: The extra attenuation of primary carbon ions in PE was partly compensated by increased secondary particles for tumor dose. In practical situations, the PE range compensators would normally cause only marginal errors as compared to intrinsic uncertainties in treatment planning, patient setup, beam delivery, and clinical response.

  11. The influence of negative ions in helium-oxygen barrier discharges: I. Laser photodetachment experiment

    NASA Astrophysics Data System (ADS)

    Tschiersch, R.; Nemschokmichal, S.; Meichsner, J.

    2016-04-01

    This work is the experimental part of a comprehensive study that aims to understand the influence of negative ions on the development of atmospheric pressure barrier discharges in electronegative systems. The investigations will be complemented by a 1D numerical fluid simulation. Laser photodetachment experiments were performed in a glow-like barrier discharge operated in helium with admixtures of oxygen up to 1 vol.% at a gas pressure of 500 mbar. The discharge gap between the glass-coated electrodes was 3 mm. The discharge properties were characterized by electrical measurements and optical emission spectroscopy. Laser photodetachment of {{\\text{O}}-} , {\\text{O}}2- , and {\\text{O}}3- was studied using the fundamental and second harmonic wavelength of a Nd-YAG laser. The laser photodetachment of negative ions influences the breakdown characteristics when the laser is fired during the prephase of the discharge only. The breakdown voltage is reduced, which indicates an enhanced pre-ionization initiated by the detached electrons. Systematic variations in the laser pulse in time, the axial laser beam position, the laser pulse energy, and the laser wavelength provided detailed knowledge on this process. The investigation underlines the importance of the discharge prephase in general and aims to differentiate between the negative ion species {{\\text{O}}-} , {\\text{O}}2- , and {\\text{O}}3- .

  12. Influence of several metal ions on the gelation activation energy of silicon tetraethoxide

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    1990-01-01

    The effects of nine metal cations Li(+), Na(+), Mg(2+), Ca(2+), Sr(2+), Cu(2+), Al(3+), La(3+), and Y(3+) on silica gel formation has been investigated by studying the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) in the presence of metal nitrates. The influence of water:TEOS mole ratio, metal ion concentration, and the reaction temperature has been investigated. The overall activation energy for gel formation has been determined from the temperature dependence of the time of gelation for each system. The activation energy for -Si-O-Si- network formation is found to be 54.5 kJ/mol. The gel formation time as well as the activation energy sharply increase in the presence of Cu(2+), Al(3+), La(3+) and Y(3+). In contrast, the presence of Li(+), Na(+), Mg(2+), Ca(2+), or Sr(2+) lowers the gelation time, but has no appreciable effect on the activation energy. This difference may be attributed to the participation or nonparticipation of the metal ions in the formation of the three-dimensional polymeric network during the polycondensation step. The concentration of metal ion Mg(2+), Ca(2+), Y(3+) or the water:TEOS mole ratio had no appreaciable effect on the gelation activation energy. A simple test has been proposed to determine whether a metal ion would act as a network intermediate or modifier in silica and other glassy networks.

  13. Influence of several metal ions on the gelation activation energy of silicon tetraethoxide

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    1988-01-01

    The effects of nine metal cations (Li(+), Na(+), Mg(2+), Ca(2+), Sr(2+), Cu(2+), Al(3+), La(3+), and Y(3+) on silica gel formation has been investigated by studying the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) in the presence of metal nitrates. The influence of water: TEOS mole ratio, metal ion concentration, and the reaction temperature has been investigated. The overall activation energy for gel formation has been determined from the temperature dependence of the time of gelation for each system. The activation energy for -Si-O-Si- network formation is found to be 54.5 kJ/mol. The gel formation time as well as the activation energy sharply increase in the presence of Cu(2+), Al(3+), La(3+) and Y(3+). In contrast, the presence of Li(+), Na(+), Mg(2+), Ca(2+), or, Sr(2+) lowers the gelation time, but has no appreciable effect on the activation energy. This difference may be attributed to the participation or nonparticipation of the metal ions in the formation of the three-dimensional polymeric network during the polycondensation step. The concentration of metal ion (Mg(2+), Ca(2+), Y(3+) or the water: TEOS mole ratio had no appreciable effect on the gelation activation energy. A simple test has been proposed to determine whether a metal ion would act as a network intermediate or modifier in silica and other glassy networks.

  14. Influence of ion/atom arrival ratio on structure and optical properties of AlN films by ion beam assisted deposition

    NASA Astrophysics Data System (ADS)

    Meng, Jian-ping; Fu, Zhi-qiang; Liu, Xiao-peng; Yue, Wen; Wang, Cheng-biao

    2014-10-01

    In order to improve the optical properties of AlN films, the influence of the ion/atom arrival ratio on the structure and optical characteristics of AlN films deposited by dual ion beam sputtering was studied by using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, spectroscopic ellipsometry and UV-vis spectroscopy. The films prepared at the ion/atom arrival ratio of 1.4 are amorphous while the crystalline quality is improved with the increase of the ion/atom arrival ratio. The films deposited at the ion/atom arrival ratio of no less than 1.8 have an approximately stoichiometric ratio and mainly consist of aluminum nitride with little aluminum oxynitride, while metallic aluminum component appears in the films deposited at the ion/atom arrival ratio of 1.4. When the ion/atom arrival ratio is not less than 1.8, films are smooth, high transmitting and dense. The films prepared with high ion/atom arrival ratio (≥1.8) display the characteristic of a dielectric. The films deposited at the ion/atom arrival ratio of 1.4 are coarse, opaque and show characteristic of cermet.

  15. Influence of crystal orientation on hardness and nanoindentation deformation in ion-irradiated stainless steels

    NASA Astrophysics Data System (ADS)

    Miura, Terumitsu; Fujii, Katsuhiko; Fukuya, Koji; Takashima, Keisuke

    2011-10-01

    The influence of crystal orientation on hardness and the range of plastic deformation caused by nanoindentation was investigated in a solution annealed type 316 stainless steel irradiated with Fe 2+ ions. The hardness was a function of grain orientation and was correlated with the Taylor factor averaged over three normal directions of the contact surface of the Berkovich indenter. The transmission electron microscope observations of the deformation microstructure under the indentations showed that the range of plastic deformation reached up to 10 times the indent depth for unirradiated material and depended on the orientation relation between the contact surface of the indenter and the slip directions. The range of plastic deformation decreased as the damage structure developed in ion irradiation.

  16. How the excluded volume architecture influences ion-mediated forces between proteins.

    PubMed

    Dahirel, V; Jardat, M; Dufrêche, J-F; Turq, P

    2007-10-01

    The effective interactions between model proteins of various shapes are computed by means of Monte Carlo simulations. In particular, we determine how the modification of the excluded volume architecture influences both entropic and purely electrostatic ion-mediated forces between proteins. We find that interprotein interactions are strongly affected by protein shape, which results in a high decrease of electrostatic screening for typical active site geometries. Effective interactions are then closer to the direct Coulombic interactions, and both affinity and selectivity are enhanced by several orders of magnitude. PMID:17994928

  17. Influence of positive ions on oscillatory processes in an electron beam with virtual cathode

    NASA Astrophysics Data System (ADS)

    Filatov, R. A.; Kalinin, Yu. A.; Khramov, A. E.; Trubetskov, D. I.

    2006-10-01

    We numerically simulate the influence of positive ions on characteristics of the microwave oscillations in a nonrelativistic electron beam with the virtual cathode formed in a decelerating field (low-voltage vircator). A numerical scheme allowing for ionization of a residual gas by an electron flow is proposed. It is shown that the residual-gas ionization in the operating chamber of a low-voltage vircator leads to a forcing of the virtual cathode out of the transit gap and to a cutoff of microwave oscillations. The obtained numerical data are confirmed by an experimental study using a low-voltage vircator model.

  18. Influence des melanges complexes organiques sur le sort des dioxines et furanes: Implications dans le developpement de facteurs de caracterisation en analyse du cycle de vie

    NASA Astrophysics Data System (ADS)

    Taing, Eric

    The environmental fate of dioxins and furans, or polychlorodibenzo-p-dioxins and -furans (PCDD/Fs), leaching from wood poles treated with pentachlorophenol (PCP) oil is modified by the presence of oil. Interactions between co-contaminants, which also exist for other pollutants within the mixtures, were shown in the specific context of risk analysis, but have never been taken into account for the generic context of life cycle assessment (LCA). This decision-making tool relies on characterization factors (CF) to estimate the potential impacts of an emitted amount of a pollutant in different impact categories such as aquatic ecotoxicity and human toxicity. For these two impact categories, CFs are calculated from a cause-effect chain that models the environmental fate, exposure and effects of the pollutant (represented by a matrix of fate FF, exposure XF and effect EF, respectively), meaning that a modification of PCDD/Fs fate induces a change in PCDD/Fs CFs. The research question is therefore as follows: In life cycle impact assessment (LCIA), to what extent would the potential impacts of PCDD/Fs on aquatic ecotoxicity and human toxicity change when taking into account the influence of a complex organic mixture on PCDD/Fs fate?. Thus, the main objective is to develop CFs of PCDD/Fs when their fate is influenced by PCP oil and compare them with the CFs of PCDD/Fs without oil for the aquatic ecotoxicity and human toxicity impact categories. A mathematic approach is established to determine the new environmental distribution of PCDD/Fs in the presence of oil and a new FF' matrix is calculated from this new distribution to obtain new CFs' integrating oil influence. FF' and CF' are then compared to FF and CF of PCDD/Fs without the oil. Finally, potential (eco)toxic impacts of the PCDD/F Canadian emissions are calculated with the new CFs' of PCDD/Fs in presence of oil. By only focusing on the results for an emission into air, freshwater and natural soil on a continental

  19. Study of the Influence Between Barium Ions and Calcium Ions on Morphology and Size of Coprecipitation in Microemulsion

    NASA Astrophysics Data System (ADS)

    Wang, Nong; Meng, Qing Luo

    2015-03-01

    In this paper, we systematically drew a series of inverse-microemulsion quasi-ternary system phase diagrams of OP-10+C8H17OH+C6H12+brine (CaCl2/BaCl2) by adjusting the ratio of CaCl2 and BaCl2. On this basis, microemulsions have been prepared with seven different molar ratios of Ca2+/Ba2+, and calcium carbonate and barium carbonate coprecipitation products were obtained by reaction with an equimolar amount of sodium carbonate. The influence of barium ion to morphology and composition of nanometer calcium carbonate were studied. These samples were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The SEM photographs indicated that when the content of Ca2+ was higher, some incomplete large cube of coprecipitation particles were formed in solution, but with the content of Ba2+ increased gradually, they formed a large number of small spherical particles, with the further increase of Ba2+ concentration, the particles mainly had structures of irregular polyhedron eventually. The measurement results of FTIR and XRD indicated that CaCO3 coprecipitation products gradually changed from calcite to the vaterite, eventually turned into being aragonite with the further increase of Ba2+ concentration.

  20. Etude de l'influence de la temperature et de l'humidite sur les proprietes mecaniques en traction des fibres de chanvre et de coco

    NASA Astrophysics Data System (ADS)

    Ho Thi, Thu Nga

    L'objectif de cette etude fut d'etablir l'effet de l'humidite et de la temperature sur la resistance en traction et le module elastique des fibres de chanvre et de coco. Deux etudes ont ete realisees afin d'atteindre cet objectif. La premiere vise l'absorption de l'humidite dans ces fibres en exposition dans l'air (de 0%RH a 80%RH) ainsi que l'absorption de l'eau dans ces fibres immergees dans l'eau aux differentes temperatures. La deuxieme consiste a mesurer la resistance en traction et le module elastique de ces fibres sous differentes conditions d'humidite et de temperature. En basant sur les resultats experimentaux obtenus, les methodes semi empiriques et de reseaux de neurones ont ete utilisees pour but de predire les proprietes en traction (resistance et module d'elasticite) des fibres de chanvre et de coco sous l'influence de l'humidite et de la temperature.

  1. Influence of crystal orientation and ion bombardment on the nitrogen diffusivity in single-crystalline austenitic stainless steel

    SciTech Connect

    Martinavicius, A.; Abrasonis, G.; Moeller, W.

    2011-10-01

    The nitrogen diffusivity in single-crystalline AISI 316L austenitic stainless steel (ASS) during ion nitriding has been investigated at different crystal orientations ((001), (110), (111)) under variations of ion flux (0.3-0.7 mA cm{sup -2}), ion energy (0.5-1.2 keV), and temperature (370-430 deg. C). The nitrogen depth profiles obtained from nuclear reaction analysis are in excellent agreement with fits using the model of diffusion under the influence of traps, from which diffusion coefficients were extracted. At fixed ion energy and flux, the diffusivity varies by a factor up to 2.5 at different crystal orientations. At (100) orientation, it increases linearly with increasing ion flux or energy. The findings are discussed on the basis of atomistic mechanisms of interstitial diffusion, potential lattice distortions, local decomposition, and ion-induced lattice vibrational excitations.

  2. Influence of crystal orientation and ion bombardment on the nitrogen diffusivity in single-crystalline austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Martinavičius, A.; Abrasonis, G.; Möller, W.

    2011-10-01

    The nitrogen diffusivity in single-crystalline AISI 316L austenitic stainless steel (ASS) during ion nitriding has been investigated at different crystal orientations ((001), (110), (111)) under variations of ion flux (0.3-0.7 mA cm-2), ion energy (0.5-1.2 keV), and temperature (370-430 °C). The nitrogen depth profiles obtained from nuclear reaction analysis are in excellent agreement with fits using the model of diffusion under the influence of traps, from which diffusion coefficients were extracted. At fixed ion energy and flux, the diffusivity varies by a factor up to 2.5 at different crystal orientations. At (100) orientation, it increases linearly with increasing ion flux or energy. The findings are discussed on the basis of atomistic mechanisms of interstitial diffusion, potential lattice distortions, local decomposition, and ion-induced lattice vibrational excitations.

  3. The influence of inner-shell electron promotion on charge exchange processes in low energy ion scattering from surfaces

    NASA Astrophysics Data System (ADS)

    Ting Li; MacDonald, R. J.

    1997-11-01

    The influence of inner-shell electron promotion on charge exchange in low energy (1-7 keV) Ne + ions scattered from the Cu (1 0 0), Ni (1 0 0) and Fe (1 1 0) surfaces has been studied systematically. The yield of Ne + ion scattered from these surfaces has been measured as a function of incident ion energy under various scattering geometries. The relative Ne + ion fraction, which is proportional to the normalised ion yield divided by the differential scattering cross section, is studied and an empirical formula for relative ion fraction has been extracted. The formula combines the charge exchanges along the incoming trajectory, during the close encounter, and along the outgoing trajectory into one simple expression. It can be concluded that inner-shell electron excitations during close encounters contribute significantly to the charge exchange in the scattering systems studied in this work.

  4. Ionic liquid lubrication: influence of ion structure, surface potential and sliding velocity.

    PubMed

    Li, Hua; Rutland, Mark W; Atkin, Rob

    2013-09-21

    Colloid probe atomic force microscopy (AFM) has been employed to investigate the nanotribology of the ionic liquid (IL)-Au(111) interface. Data is presented for four ILs, 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([EMIM] FAP), 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([BMIM] FAP), 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM] FAP) and 1-butyl-3-methylimidazolium iodide ([BMIM] I), at different Au(111) surface potentials. Lateral forces vary as a function of applied surface potential and ion structure because the composition of the confined ion layer changes from cation-enriched (at negative potentials) to mixed (at 0 V), and to anion-enriched (at positive potentials). ILs with FAP(-) anions all exhibit similar nanotribology: low friction at negative potentials and higher friction at positive potentials. [BMIM] I displays the opposite behaviour, as an I(-) anion-enriched layer is more lubricating than either the [BMIM](+) or FAP(-) layers. The effect of cation charged group (charge-delocalised versus charged-localised) was investigated by comparing [BMIM] FAP with 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate ([Py(1,4)] FAP). [BMIM] FAP is less lubricating at negative potentials, but more lubricating at positive potentials. This indicated that even at positive potentials the cation concentration in the boundary layer is sufficiently high to influence lubricity. The influence of sliding velocity on lateral force was investigated for the [EMIM] FAP-Au(111) system. At neutral potentials the behaviour is consistent with a discontinuous sliding process. When a positive or negative potential bias is applied, this effect is less pronounced as the colloid probe slides along a better defined ion plane. PMID:23836254

  5. In vitro behavior of human intestinal mucosa. The influence of acetyl choline on ion transport.

    PubMed Central

    Isaacs, P E; Corbett, C L; Riley, A K; Hawker, P C; Turnberg, L A

    1976-01-01

    The possibility that the autonomic nervous system may influence the function of intestinal mucosa was investigated by assessing the effect of acetyl choline on ion transport in human intestine. Isolated pieces of stripped ileal mucosa were mounted in Perspex flux-chambers and bathed in isotonic glucose Ringer's solution. Acetyl choline caused a rise in mean potential difference (8.8-12.3 mV, P less than 0.002) and short circuit current (287.7-417.2 muA-cm-2, P less than 0.01) (n = 12), observable at a concentration of 0.01 mM and maximal at 0.1 mM. This effect was enhanced by neostigmine and blocked by atropine. Isotopic flux determinations revealed a change from a small mean net Cl absorption (58) to a net Cl secretion (-4.3mueq-cm-2-h-1P less than 0.001) due predominantly to an increase in the serosal to mucosal unidirectional flux of Cl (10.63-14.35 mueq-cm-2-h-1P less than 0.05) and a smaller reduction in the mucosal to serosal flux (11.22 to 10.02 mueq-cm-2-h-1P less than 0.05). Unidirectional and net Na transport was unaffected. A similar electrical and ion transport response was observed in a single study of two pieces of jejunal mucosa. In the absence of glucose net chloride secretion was produced and again an insignificant effect on net sodium transport was noted. Acetyl choline did not provoke a sustained effect on mucosal cyclic adenine nucleotide levels although a short-lived cyclic adenine nucleotide response was seen in some tissues 20-30 s after drug addition. These studies demonstrate that acetyl choline does influence human intestinal ion transport by stimulating chloride secretion and suggest a possible mechanism by which the parasympathetic nervous system could be concerned in the control of ion transport. Images PMID:182722

  6. Soft Landing of Mass-Selected Gold Clusters: Influence of Ion and Ligand on Charge Retention and Reactivity

    SciTech Connect

    Johnson, Grant E.; Laskin, Julia

    2015-02-01

    Herein, we employ a combination of reduction synthesis in solution, soft landing of mass-selected precursor and product ions, and in situ time-of-flight secondary ion mass spectrometry (TOF-SIMS) to examine the influence of ion and the length of diphosphine ligands on the charge retention and reactivity of ligated gold clusters deposited onto self-assembled monolayer surfaces (SAMs). Product ions (Au10L42+, (10,4)2+, L = 1,3-bis(diphenyl-phosphino)propane, DPPP) were prepared through in-source collision induced dissociation (CID) and precursor ions [(8,4)2+, L = 1,6-bis(diphenylphosphino)hexane, DPPH] were synthesized in solution for comparison to (11,5)3+ precursor ions ligated with DPPP investigated previously (ACS Nano 2012, 6, 573 and J. Phys. Chem. C. 2012, 116, 24977). Similar to (11,5)3+ precursor ions, the (10,4)2+ product ions are shown to retain charge on 1H,1H,2H,2H-perfluorodecanethiol monolayers (FSAMs). Additional abundant peaks at higher m/z indicative of reactivity are observed in the TOF-SIMS spectrum of (10,4)2+ product ions that are not seen for (11,5)3+ precursor ions. The abundance of (10,4)2+ on 16-mercaptohexadecanoic acid (COOH-SAMs) is demonstrated to be lower than on FSAMs, consistent with partial reduction of charge. The (10,4)2+ product ion on 1-dodecanethiol (HSAMs) exhibits peaks similar to those seen on the COOH-SAM. On the HSAM, higher m/z peaks indicative of reactivity are observed similar to those on the FSAM. The (8,4)2+ DPPH precursor ions are shown to retain charge on FSAMs similar to (11,5)3+ precursor ions prepared with DPPP. An additional peak corresponding to attachment of one gold atom to (8,4)2+ is observed at higher m/z for DPPH-ligated clusters. On the COOH-SAM, (8,4)2+ is less abundant than on the FSAM consistent with partial neutralization. The results indicate that although retention of charge by product ions generated by CID is similar to precursor ions their reactivity during analysis with SIMS is different

  7. The influence of metal artefacts on the range of ion beams

    NASA Astrophysics Data System (ADS)

    Jäkel, Oliver; Reiss, Petra

    2007-02-01

    The influence of artefacts due to metal implants on the range of ion beams is investigated, using a geometrically well-defined head and pelvic phantom together with inserts from steel, titanium and tungsten. The ranges along various beam paths including artefacts were calculated from the TPS and compared to known calculations for phantoms without any insert. In the head phantom, beams intersecting the streak artefacts lead to errors in the range of around or below 1%, which is mainly due to a cancellation of various effects. Beams through the metal or close to it show an underestimation of 3.5% of the range for tungsten. For the pelvic phantom, a large underestimation of the range is observed for a lateral path through the metal insert. In the case of tungsten and steel, range errors of -5% and -18% are observed, respectively. Such beam paths are typically used for pelvic tumours in radiotherapy with ion beams. For beams in the anterior-posterior direction through the inserts, an overestimation of ion ranges of up to 3% for titanium and 8% for steel is expected, respectively. Beam paths outside the metal insert show a large cancellation for the lateral beams (leading to errors of around 1% only) and somewhat higher errors for anterior-posterior beams (around 3% for titanium and 6% for steel). The analysis of CT data of patients with dental implants of gold as compared to patients with healthy teeth also showed a significant effect of the artefacts on the distribution of HU in the data, namely a redistribution of HU to higher and lower values as compared to patients with healthy teeth. The corresponding mean range variation was a 2.5% reduction in the data with artefacts as compared to the data without artefacts. It is concluded that beam paths through metal implants should generally be avoided in proton and ion therapy. In this case, the underestimation of ion range due to artefacts alone may amount to 3% for dental fillings and up to 5% and 18% for hip prosthesis

  8. Heavy-ion inertial fusion: influence of target gain on accelerator parameters for vacuum-propagation regimes in reaction chambers

    SciTech Connect

    Mark, J.W.K.; Bangerter, R.O.; Barletta, W.A.; Fawley, W.M.; Judd, D.L.

    1982-03-04

    Target physics imposes requirements on the design of inertial fusion drivers. The influence of beam propagation in near vacuum fusion reaction chambers is evaluated for the relation between target gain and the phase-space requirements of heavy-ion accelerators. Initial results suggest that neutralization of the ion beam has a much greater positive effect than the deleterious one of beam stripping provided that the fusion chamber pressure is < 10/sup -3/ torr (of Li vapor or equivalent).

  9. Cathodically induced antimony for rechargeable Li-ion and Na-ion batteries: The influences of hexagonal and amorphous phase

    NASA Astrophysics Data System (ADS)

    Yang, Yingchang; Yang, Xuming; Zhang, Yan; Hou, Hongshuai; Jing, Mingjun; Zhu, Yirong; Fang, Laibing; Chen, Qiyuan; Ji, Xiaobo

    2015-05-01

    Cathodic corrosion, a green electrochemical method, has been employed to obtain Sb nanomaterials utilized as anode material for lithium-ion batteries and sodium-ion batteries. Interestingly, two different corrosion mechanisms are found, coming from the impact of electrolyte, resulting in the formation of hexagonal and amorphous Sb in aqueous and organic solution, respectively. With the help of water-soluble carboxymethyl cellulose binder and the electrolyte additive fluoroethylene carbonate, both hexagonal and amorphous Sb electrodes exhibit good cycling stability when utilized as anode materials for lithium-ion batteries and sodium-ion batteries. Additionally, both the hexagonal and amorphous Sb electrodes show very good rate capability in lithium-ion batteries. Even at high current density (2000 mA g-1), the hexagonal and amorphous Sb give reversible capacities of 422 and 379 mA h g-1, respectively. Surprisingly, when used as anode materials for sodium-ion batteries, the hexagonal Sb electrode exhibits a good rate performance of 632, 625, 569, 515 and 426 mA h g-1 at a current density of 100, 200, 500, 1000, and 2000 mA g-1, respectively. However, limited rate performance is observed from the amorphous Sb electrode in case of sodium-ion battery due to the large impedance.

  10. The Influence of Contact Adsorbed Ions on the Photoelectrochemical Behaviour of α-HgS

    NASA Astrophysics Data System (ADS)

    Repenning, D.; Schumawcher, R.; Schindler, R. N.

    1982-04-01

    Results are reported to describe the influence of additives on the photoelectrochemical properties of the liquid junction α-HgS/electrolyte. The semiconductor electrodes were prepared by sublimation of α-HgS on Au substrates. The electrolyte was modified by additives such as Cl-, Br-, J-, and CN- ions. It was found that these anions play an important role in determining the flat band Vfb and the transition potential Vtr. Generally, both the nature and the concentration of the additives affect Vfb and Vtr.The results are interpreted in terms of contact adsorption of the used anions. It is further indicated that the adsorptive properties can be correlated to a possible chemical reaction of mercury cations with halide anions to form insoluble layers at the surface.

  11. Ion channel modifying agents influence the electrical activity generated by canine intrinsic cardiac neurons in situ.

    PubMed

    Thompson, G W; Horackova, M; Armour, J A

    2000-04-01

    This study was designed to establish whether agents known to modify neuronal ion channels influence the behavior of mammalian intrinsic cardiac neurons in situ and, if so, in a manner consistent with that found previously in vitro. The activity generated by right atrial neurons was recorded extracellularly in varying numbers of anesthetized dogs before and during continuous local arterial infusion of several neuronal ion channel modifying agents. Veratridine (7.5 microM), the specific modifier of Na+-selective channels, increased neuronal activity (95% above control) in 80% of dogs tested (n = 25). The membrane depolarizing agent potassium chloride (40 mM) reduced neuronal activity (43% below control) in 84% of dogs tested (n = 19). The inhibitor of voltage-sensitive K+ channels, tetraethylammonium (10 mM), decreased neuronal activity (42% below control) in 73% of dogs tested (n = 11). The nonspecific potassium channel inhibitor barium chloride (5 mM) excited neurons (47% above control) in 13 of 19 animals tested. Cadmium chloride (200 microM), which inhibits Ca2+-selective channels and Ca2+-dependent K+ channels, increased neuronal activity (65% above control) in 79% of dogs tested (n = 14). The specific L-type Ca2+ channel blocking agent nifedipine (5 microM) reduced neuronal activity (52% blow control in 72% of 11 dogs tested), as did the nonspecific inhibitor of L-type Ca2+ channels, nickel chloride (5 mM) (36% below control in 69% of 13 dogs tested). Each agent induced either excitatory or inhibitory responses, depending on the agent tested. It is concluded that specific ion channels (I(Na), I(CaL), I(Kv), and I(KCa)) that have been associated with intrinsic cardiac neurons in vitro are involved in their capacity to generate action potentials in situ. PMID:10772056

  12. Influence of chemical microstructure of single-ion polymeric electrolyte membranes on performance of lithium-ion batteries.

    PubMed

    Zhang, Yunfeng; Rohan, Rupesh; Cai, Weiwei; Xu, Guodong; Sun, Yubao; Lin, An; Cheng, Hansong

    2014-10-22

    A novel protocol to generate and control porosity in polymeric structures is presented for fabrication of single ion polymer electrolyte (SIPE) membranes for lithium ion batteries. A series of SIPEs with varying ratios of aliphatic and aromatic segments was successfully synthesized and subsequently blended with PVDF-HFP to fabricate membranes of various sizes of pores. The membranes were characterized using techniques including SEM, solvent uptake capacity measurement and ionic conductivity. We demonstrate that appropriate membrane porosity enhances ionic conductivity, reduces interfacial resistance between electrodes and electrolyte and ultimately boosts performance of Li-ion batteries. The implication of the structure-performance relationship for battery design is discussed. PMID:25225970

  13. The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon.

    PubMed

    Khara, Galvin S; Murphy, Samuel T; Daraszewicz, Szymon L; Duffy, Dorothy M

    2016-10-01

    The swift heavy ion (SHI) irradiation of materials is often modelled using the two-temperature model. While the model has been successful in describing SHI damage in metals, it fails to account for the presence of a bandgap in semiconductors and insulators. Here we explore the potential to overcome this limitation by explicitly incorporating the influence of the bandgap in the parameterisation of the electronic specific heat for Si. The specific heat as a function of electronic temperature is calculated using finite temperature density functional theory with three different exchange correlation functionals, each with a characteristic bandgap. These electronic temperature dependent specific heats are employed with two-temperature molecular dynamics to model ion track creation in Si. The results obtained using a specific heat derived from density functional theory showed dramatically reduced defect creation compared to models that used the free electron gas specific heat. As a consequence, the track radii are smaller and in much better agreement with experimental observations. We also observe a correlation between the width of the band gap and the track radius, arising due to the variation in the temperature dependence of the electronic specific heat. PMID:27501917

  14. The influence of microstructure on blistering and bubble formation by He ion irradiation in Al alloys

    NASA Astrophysics Data System (ADS)

    Soria, S. R.; Tolley, A.; Sánchez, E. A.

    2015-12-01

    The influence of microstructure and composition on the effects of ion irradiation in Al alloys was studied combining Atomic Force Microscopy, Scanning Electron Microscopy and Transmission Electron Microscopy. For this purpose, irradiation experiments with 20 keV He+ ions at room temperature were carried out in Al, an Al-4Cu (wt%) supersaturated solid solution, and an Al-5.6Cu-0.5Si-0.5Ge (wt.%) alloy with a very high density of precipitates, and the results were compared. In Al and Al-4Cu, He bubbles were found with an average size in between 1 nm and 2 nm that was independent of fluence. The critical fluence for bubble formation was higher in Al-4Cu than in Al. He bubbles were also observed below the critical fluence after post irradiation annealing in Al-4Cu. The incoherent interfaces between the equilibrium θ phase and the Al matrix were found to be favorable sites for the formation of He bubbles. Instead, no bubbles were observed in the precipitate rich Al-5.6Cu-0.5Si-0.5Ge alloy. In all alloys, blistering was observed, leading to surface erosion by exfoliation. The blistering effects were more severe in the Al-5.6Cu-0.5Si-0.5Ge alloy, and they were enhanced by increasing the fluence rate.

  15. Influence of bicarbonate and carbonate ions on sonochemical degradation of Rhodamine B in aqueous phase.

    PubMed

    Merouani, Slimane; Hamdaoui, Oualid; Saoudi, Fethi; Chiha, Mahdi; Pétrier, Christian

    2010-03-15

    The influence of bicarbonate and carbonate ions on sonolytic degradation of cationic dye, Rhodamine B (RhB), in water was investigated. As a consequence of ultrasonic cavitation that generates .OH radicals, carbonate radicals were secondary products of water sonochemistry when it contains dissolved bicarbonate or carbonate ions. The results clearly demonstrated the significant intensification of sonolytic destruction of RhB in the presence of bicarbonate and carbonate, especially at lower dye concentrations. Degradation intensification occurs because carbonate radicals sonochemically formed undergo radical-radical recombination at a lesser extent than hydroxyl radicals. The generated carbonate radicals are likely able to migrate far from the cavitation bubbles towards the solution bulk and are suitable for degradation of an organic dye such as RhB. Therefore, at low dye concentrations, carbonate radical presents a more selective reactivity towards RhB molecules than hydroxyl radical. In the presence of bicarbonate, degradation rate reached a maximum at 3 g L(-1) bicarbonate, but subsequent addition retards the destruction process. In RhB solutions containing carbonate, the oxidation rate gradually increased with increasing carbonate concentration up to 10 g L(-1) and slightly decreased afterward. Carbonate radicals sonochemically generated are suitable for total removal of COD of sonicated RhB solutions. PMID:19910116

  16. Influence of irradiation with swift heavy ions on multilayer Si/SiO{sub 2} heterostructures

    SciTech Connect

    Kachurin, G. A. Cherkova, S. G.; Marin, D. V.; Volodin, V. A.; Cherkov, A. G.; Antonenko, A. Kh.; Kamaev, G. N.; Skuratov, V. A.

    2013-03-15

    The influence of Xe ions with an energy of 167 MeV and a dose in the range 10{sup 12}-3 Multiplication-Sign 10{sup 13} cm{sup -2} on heterostructures consisting of six pairs of Si/SiO{sub 2} layers with the thicknesses {approx}8 and {approx}10 nm, correspondingly, is studied. As follows from electron microscopy data, the irradiation breaks down the integrity of the layers. At the same time, Raman studies give evidence for the enhancement of scattering in amorphous silicon. In addition, a yellow-orange band inherent to small-size Si clusters released from SiO{sub 2} appears in the photoluminescence spectra. Annealing at 800 Degree-Sign C recovers the SiO{sub 2} network, whereas annealing at 1100 Degree-Sign C brings about the appearance of a more intense photoluminescence peak at {approx}780 nm typical of Si nanocrystals. The 780-nm-peak intensity increases, as the irradiation dose is increased. It is thought that irradiation produces nuclei, which promote Si-nanocrystal formation upon subsequent annealing. The processes occur within the tracks due to strong heating because of ionization losses of the ions.

  17. Influence of material removal programming on ion beam figuring of high-precision optical surfaces

    NASA Astrophysics Data System (ADS)

    Liao, Wenlin; Dai, Yifan; Xie, Xuhui

    2014-09-01

    Ion beam figuring (IBF) provides a nanometer/subnanometer precision fabrication technology for optical components, where the surface materials on highlands are gradually removed by the physical sputtering effect. In this deterministic method, the figuring process is usually divided into several iterations and the sum of the removed material in each iteration is expected to approach the ideally removed material as nearly as possible. However, we find that the material removal programming in each iteration would influence the surface error convergence of the figuring process. The influence of material removal programming on the surface error evolution is investigated through the comparative study of the contour removal method (CRM) and the geometric proportion removal method (PRM). The research results indicate that the PRM can maintenance the smoothness of the surface topography during the whole figuring process, which would benefit the stable operation of the machine tool and avoid the production of mid-to-high spatial frequency surface errors. Additionally, the CRM only has the corrective effect on the area above the contour line in each iteration, which would result in the nonuniform convergence of the surface errors in various areas. All these advantages distinguish PRM as an appropriate material removal method for ultraprecision optical surfaces.

  18. The Influence of Drift Gas Composition on the Separation Mechanism in Traveling Wave Ion Mobility Spectrometry: Insight from Electrodynamic Simulations

    PubMed Central

    May, Jody C.; McLean, John A.

    2013-01-01

    The influence of three different drift gases (helium, nitrogen, and argon) on the separation mechanism in traveling wave ion mobility spectrometry is explored through ion trajectory simulations which include considerations for ion diffusion based on kinetic theory and the electrodynamic traveling wave potential. The model developed for this work is an accurate depiction of a second-generation commercial traveling wave instrument. Three ion systems (cocaine, MDMA, and amphetamine) whose reduced mobility values have previously been measured in different drift gases are represented in the simulation model. The simulation results presented here provide a fundamental understanding of the separation mechanism in traveling wave, which is characterized by three regions of ion motion: (1) ions surfing on a single wave, (2) ions exhibiting intermittent roll-over onto subsequent waves, and (3) ions experiencing a steady state roll-over which repeats every few wave cycles. These regions of ion motion are accessed through changes in the gas pressure, wave amplitude, and wave velocity. Resolving power values extracted from simulated arrival times suggest that momentum transfer in helium gas is generally insufficient to access regions (2) and (3) where ion mobility separations occur. Ion mobility separations by traveling wave are predicted to be effectual for both nitrogen and argon, with slightly lower resolving power values observed for argon as a result of band-broadening due to collisional scattering. For the simulation conditions studied here, the resolving power in traveling wave plateaus between regions (2) and (3), with further increases in wave velocity contributing only minor improvements in separations. PMID:23888124

  19. Effet de l'énergie du faisceau d'ions servant à l'assistance du dépôt de matériaux organiques utilisés pour réaliser des diodes électroluminescentes

    NASA Astrophysics Data System (ADS)

    Antony, R.; Moliton, A.; Ratier, B.

    1998-06-01

    Light emitting diode based on the structure ITO/Alq3/Ca-Al lead to enhanced quantum efficiency when the Alq3 active layer is obtained by IBAD (Ion Beam Assisted Deposition): with Iodine ions, the optimization (quantum efficiency multiplied by a factor10) is obtained for an ion energy equal to 100eV. La réalisation de diodes électroluminescentes basées sur la structure ITO/Alq3/Ca-Al conduit à des performances améliorées lorsque le dépôt de la couche active Alq3 est effectué avec l'assistance d'un faisceau d'ions; l'optimisation (rendement quantique interne accru d'un ordre de grandeur) correspond à des ions Iode d'énergie 100eV.

  20. Influence of Atmospheric Solar Radiation Absorption on Photodestruction of Ions at D-Region Altitudes of the Ionosphere

    NASA Astrophysics Data System (ADS)

    Pavlov, A. V.

    2016-04-01

    The influence of atmospheric solar radiation absorption on the photodetachment, dissociative photodetachment, and photodissociation rate coefficients (photodestruction rate coefficients) of O-, Cl-, O2 -, O3 -, OH-, NO2 -, NO3 -, O4 -, OH-(H2O), CO3 -, CO4 -, ONOO-, HCO3 -, CO3 -(H2O), NO3 -(H2O), O2 +(H2O), O4 +, N4 +, NO+(H2O), NO+(H2O)2, H+(H2O) n for n = 2-4, NO+(N2), and NO+(CO2) at D-region altitudes of the ionosphere is studied. A numerical one-dimensional time-dependent neutral atmospheric composition model has been developed to estimate this influence. The model simulations are carried out for the geomagnetically quiet time period of 15 October 1998 at moderate solar activity over the Boulder ozonesonde. If the solar zenith angle is not more than 90° then the strongest influence of atmospheric solar radiation absorption on photodestruction of ions is found for photodissociation of CO4 - ions when CO3 - ions are formed. It follows from the calculations that decreases in the photodestruction rate coefficients of ions under consideration caused by this influence are less than 2 % at 70 km altitude and above this altitude if the solar zenith angle does not exceed 90°.

  1. Influence of Atmospheric Solar Radiation Absorption on Photodestruction of Ions at D-Region Altitudes of the Ionosphere

    NASA Astrophysics Data System (ADS)

    Pavlov, A. V.

    2016-07-01

    The influence of atmospheric solar radiation absorption on the photodetachment, dissociative photodetachment, and photodissociation rate coefficients (photodestruction rate coefficients) of O-, Cl-, O2 -, O3 -, OH-, NO2 -, NO3 -, O4 -, OH-(H2O), CO3 -, CO4 -, ONOO-, HCO3 -, CO3 -(H2O), NO3 -(H2O), O2 +(H2O), O4 +, N4 +, NO+(H2O), NO+(H2O)2, H+(H2O) n for n = 2-4, NO+(N2), and NO+(CO2) at D-region altitudes of the ionosphere is studied. A numerical one-dimensional time-dependent neutral atmospheric composition model has been developed to estimate this influence. The model simulations are carried out for the geomagnetically quiet time period of 15 October 1998 at moderate solar activity over the Boulder ozonesonde. If the solar zenith angle is not more than 90° then the strongest influence of atmospheric solar radiation absorption on photodestruction of ions is found for photodissociation of CO4 - ions when CO3 - ions are formed. It follows from the calculations that decreases in the photodestruction rate coefficients of ions under consideration caused by this influence are less than 2 % at 70 km altitude and above this altitude if the solar zenith angle does not exceed 90°.

  2. Irradiation influence on Mylar and Makrofol induced by argon ions in a plasma immersion ion implantation system

    NASA Astrophysics Data System (ADS)

    Hassan, A.; El-Saftawy, A. A.; Aal, S. A. Abd El; Ghazaly, M. El

    2015-08-01

    Mylar and Makrofol polycarbonate polymers were irradiated by Ar ions in a plasma immersion ion implantation (PIII) system. The surface wettability of both polymers was investigated by employing the contact angle method. The measured contact angles were found to depend on the surface layer properties. Good wetting surfaces were found to depend not only on surface roughness but also on its chemistry that analyzed by Fourier transform infrared (FTIR) spectroscopy. Surfaces topography and roughness was investigated and correlated to their surface energy which studied with the aid of acid-base model for evaluating the improvement of surface wettability after irradiation. PIII improves polymers surface properties efficiently in a controllable way.

  3. Stress influenced trapping processes in Si based multi-quantum well structures and heavy ions implanted Si

    SciTech Connect

    Ciurea, Magdalena Lidia Lazanu, Sorina

    2014-10-06

    Multi-quantum well structures and Si wafers implanted with heavy iodine and bismuth ions are studied in order to evaluate the influence of stress on the parameters of trapping centers. The experimental method of thermostimullatedcurrents without applied bias is used, and the trapping centers are filled by illumination. By modeling the discharge curves, we found in multilayered structures the parameters of both 'normal' traps and 'stress-induced' ones, the last having a Gaussian-shaped temperature dependence of the cross section. The stress field due to the presence of stopped heavy ions implanted into Si was modeled by a permanent electric field. The increase of the strain from the neighborhood of I ions to the neighborhood of Bi ions produces the broadening of some energy levels and also a temperature dependence of the cross sections for all levels.

  4. Selective Permeability of Uranyl Peroxide Nanocages to Different Alkali Ions: Influences from Surface Pores and Hydration Shells

    NASA Astrophysics Data System (ADS)

    Gao, Yunyi; Szymanowski, Jennifer; Burns, Peter; Liu, Tianbo

    The precise guidance to different ions across the biological channels is essential for many biological processes. An artificial nanopore system will facilitate the study of ion transport mechanism through nanosized channels and offer new views for designing nanodevices. Here we reveal that a 2.5-nm-size, fullerene-shaped molecular cluster Li48+mK12(OH)m[UO2(O2) (OH)]60-(H2O)n (m ~20 and n ~310) (U60) shows selective permeability to different alkali ions. The sub-nanometer pores on the water-ligand-rich surface of U60 are able to block Rb+ and Cs+ ions from passing through, while allow Na+ and K+ ions, which possess larger hydrated sizes, to enter the interior space of U60. An interestingly high entropy gain during the binding process between U60 and alkali ions suggest that the hydration shells of Na+i/K+ and U60 are damaged during the interaction. The ion selectivity of U60 is greatly influenced by both the morphologies of surface nanopores and the dynamics of the hydration shells. This material is based upon work supported as part of the Materials Science of Actinides Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001089.

  5. The calculation of electron chemical potential and ion charge state and their influence on plasma conductivity in electrical explosion of metal wire

    SciTech Connect

    Shi, Zongqian; Wang, Kun; Li, Yao; Shi, Yuanjie; Wu, Jian; Jia, Shenli

    2014-03-15

    The electron chemical potential and ion charge state (average ion charge and ion distribution) are important parameters in calculating plasma conductivity in electrical explosion of metal wire. In this paper, the calculating method of electron chemical potential and ion charge state is discussed at first. For the calculation of electron chemical potential, the ideal free electron gas model and Thomas-Fermi model are compared and analyzed in terms of the coupling constant of plasma. The Thomas-Fermi ionization model, which is used to calculate ion charge state, is compared with the method based on Saha equation. Furthermore, the influence of electron degenerated energy levels and ion excited states in Saha equation on the ion charge state is also analyzed. Then the influence of different calculating methods of electron chemical potential and ion charge state on plasma conductivity is discussed by applying them in the Lee-More conductivity model.

  6. Influence of sugar cane burning on aerosol soluble ion composition in Southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Allen, A. G.; Cardoso, A. A.; da Rocha, G. O.

    2004-09-01

    Seasonal variability in the major soluble ion composition of atmospheric particulate matter in the principal sugar cane growing region of central São Paulo State indicates that pre-harvest burning of sugar cane plants is an important influence on the regional scale aerosol chemistry. Samples of particulate matter were collected between April 1999 and February 2001 in coarse (> 3.5 μm) and fine (< 3.5 μm) fractions, and analysed for HCOO-, CH3COO-, C2O42- , SO42-, NO3-, Cl-, Na+, K+, NH4+, Mg2+ and Ca2+. Results indicated that the principal sources of the aerosols investigated were local or regional in nature (scale of tens to a few hundreds of km), and that differences between air masses of varying origins were small. Fine particles were typically acidic, containing secondary nitrates, sulphates and organic species. Coarse fraction concentrations were mainly influenced by physical parameters (wind speed, movement of vehicles and surface condition) affecting rates of re-suspension, although secondary nitrate and sulphate were also present in the larger particles. Concentrations of all measured species except sodium and chloride were higher during the burning season. Although concentrations were lower than often found in polluted urban environments, the massive increases during much of the year, due to a single anthropogenic activity (sugar cane burning) are indicative of a very large perturbation of the lower troposphere in the region relative to the natural condition. These aerosols are suspected of promoting respiratory disease. They also represent an important mechanism for the tropospheric transport of species relevant to surface acidification (sulphates, nitrates, ammonium and organic acids) and soil nutrient status (potassium, nitrogen, ammonium, calcium), so their impact on fragile natural ecosystems (following deposition) needs to be considered.

  7. Needle-like ion-doped hydroxyapatite crystals influence osteogenic properties of PCL composite scaffolds.

    PubMed

    Guarino, V; Veronesi, F; Marrese, M; Giavaresi, G; Ronca, A; Sandri, M; Tampieri, A; Fini, M; Ambrosio, Luigi

    2016-02-01

    Surface topography and chemistry both play a crucial role on influencing cell response in 3D porous scaffolds in terms of osteogenesis. Inorganic materials with peculiar morphology and chemical functionalities may be proficiently used to improve scaffold properties-in the bulk and along pore surface-promoting in vitro and in vivo osseous tissue in-growth. The present study is aimed at investigating how bone regenerative properties of composite scaffolds made of poly(Ɛ-caprolactone) (PCL) can be augmented by the peculiar properties of Mg(2+) ion doped hydroxyapatite (dHA) crystals, mainly emphasizing the role of crystal shape on cell activities mediated by microstructural properties. At the first stage, the study of mechanical response by crossing experimental compression tests and theoretical simulation via empirical models, allow recognizing a significant contribution of dHA shape factor on scaffold elastic moduli variation as a function of the relative volume fraction. Secondly, the peculiar needle-like shape of dHA crystals also influences microscopic (i.e. crystallinity, adhesion forces) and macroscopic (i.e. roughness) properties with relevant effects on biological response of the composite scaffold: differential scanning calorimetry (DSC) analyses clearly indicate a reduction of crystallization heat-from 66.75 to 43.05 J g(-1)-while atomic force microscopy (AFM) ones show a significant increase of roughness-from (78.15  ±  32.71) to (136.13  ±  63.21) nm-and of pull-off forces-from 33.7% to 48.7%. Accordingly, experimental studies with MG-63 osteoblast-like cells show a more efficient in vitro secretion of alkaline phosphatase (ALP) and collagen I and a more copious in vivo formation of new bone trabeculae, thus suggesting a relevant role of dHA to support the main mechanisms involved in bone regeneration. PMID:26928781

  8. Endogenous minerals have influences on surface electrochemistry and ion exchange properties of biochar.

    PubMed

    Zhao, Ling; Cao, Xinde; Zheng, Wei; Wang, Qun; Yang, Fan

    2015-10-01

    The feedstocks for biochar production are diverse and many of them contain various minerals in addition to being rich in carbon. Twelve types of biomass classified into 2 categories: plant-based and municipal waste, were employed to produce biochars under 350 °C and 500 °C. Their pH, point of zero net charge (PZNC), zeta potential, cation and anion exchange capacity (CEC and AEC) were analyzed. The municipal waste-based biochars (MW-BC) had higher mineral levels than the plant-based biochars (PB-BC). However, the water soluble mineral levels were lower in the MW-BCs due to the dominant presence of less soluble minerals, such as CaCO3 and (Ca,Mg)3(PO4)2. The higher total minerals in MW-BCs accounted for the higher PZNC (5.47-9.95) than in PB-BCs (1.91-8.18), though the PZNCs of the PB-BCs increased more than that of the MW-BCs as the production temperature rose. The minerals had influence on the zeta potentials via affecting the negative charges of biochars and the ionic strength of solution. The organic functional groups in PB-BCs such as -COOH and -OH had a greater effect on the CEC and AEC, while the minerals had a greater effect on that of MW-BCs. The measured CEC and AEC values had a strong positive correlation with the total amount of soluble cations and anions, respectively. Results indicated that biochar surface charges depend not only on the organic functional groups, but also on the minerals present and to some extent, minerals have more influences on the surface electrochemistry and ion exchange properties of biochar. PMID:25974107

  9. Influence of the ion irradiation on the properties of β-FeSi 2 layers prepared by ion beam assisted deposition

    NASA Astrophysics Data System (ADS)

    Barradas, N. P.; Panknin, D.; Wieser, E.; Schmidt, B.; Betzl, M.; Mücklich, A.; Skorupa, W.

    1997-05-01

    β-FeSi 2 layers on Si substrates were produced by ion beam assisted deposition (IBAD). The influence of the deposition parameters on the structure was studied by Rutherford backscattering, X-ray diffraction, cross-section transmission electron microscopy, and scanning electron microscopy. The layers grow in a columnar way with pin-holes and their surface is rough. An IBAD process with low Ar energy ( EAr = 200 eV) and low Ar ion to Fe atom ratio ( {I Ar}/{A Fe} = 0.15 ) improves the layer structure in comparison to samples prepared without Ar irradiation. Less pin-holes are formed, and the roughness shows a minimum. The roughness increases for larger values of EAr or {I Ar}/{A Fe}. All samples are polycrystalline but with a pronounced texture. The preferential orientation FeSi 2(110,101)∥Si(001), with a few degrees misorientation, is found. This preferred grain orientation is also enhanced by the IBAD process. Hall effect measurements were done and the I-V characteristics of the samples were measured. The results are discussed in relation with the influence of the ion beam.

  10. Influence of proline position upon the ion channel activity of alamethicin.

    PubMed Central

    Kaduk, C; Duclohier, H; Dathe, M; Wenschuh, H; Beyermann, M; Molle, G; Bienert, M

    1997-01-01

    Alamethicin, a 20-residue peptaibol, induces voltage-dependent ion channels in lipid bilayers according to the barrel-stave model. To study relationships between the proline-14-induced kink region and the channel-forming behavior of the peptide, a set of alamethicin analogs with proline incorporated at positions 11, 12, 13, 14, 15, 16, and 17, respectively, as well as an analog with alanine instead of proline at position 14 were synthesized. Macroscopic conductance experiments show that the voltage dependence of the peptides is conserved although slightly influenced, but the apparent mean number of monomers forming the channels is significantly reduced when proline is not located at position 14. This is confirmed in single-channel experiments. The analogs with proline next to position 14 (i.e., 13, 15, 16) show stable conductance levels, but of reduced number, which follows the order Alam-P14 > Alam-P15 > Alam-P16 > Alam-P13. This reduction in the number of levels is connected with changes in the lifetime of the channels. Analogs with proline at position 11, 12, or 17 produce erratic, extremely short-lived current events that could not be resolved. The changes in functional properties are related to structural properties as probed by circular dichroism. The results indicate that proline at position 14 results in optimal channel activity, whereas channels formed by the analogs bearing proline at different positions are considerably less stable. PMID:9129817

  11. Influences of specific ions in groundwater on concrete degradation in subsurface engineered barrier system.

    PubMed

    Lin, Wen-Sheng; Liu, Chen-Wuing; Li, Ming-Hsu

    2016-01-01

    Many disposal concepts currently show that concrete is an effective confinement material used in engineered barrier systems (EBS) at a number of low-level radioactive waste (LLW) disposal sites. Cement-based materials have properties for the encapsulation, isolation, or retardation of a variety of hazardous contaminants. The reactive chemical transport model of HYDROGEOCHEM 5.0 was applied to simulate the effect of hydrogeochemical processes on concrete barrier degradation in an EBS which has been proposed to use in the LLW disposal site in Taiwan. The simulated results indicated that the main processes that are responsible for concrete degradation are the species induced from hydrogen ion, sulfate, and chloride. The EBS with the side ditch drainage system effectively discharges the infiltrated water and lowers the solute concentrations that may induce concrete degradation. The redox processes markedly influence the formations of the degradation materials. The reductive environment in the EBS reduces the formation of ettringite in concrete degradation processes. Moreover, the chemical conditions in the concrete barriers maintain an alkaline condition after 300 years in the proposed LLW repository. This study provides a detailed picture of the long-term evolution of the hydrogeochemical environment in the proposed LLW disposal site in Taiwan. PMID:27376013

  12. Automated Potentiometric Titrations in KCl/Water-Saturated Octanol: Method for Quantifying Factors Influencing Ion-Pair Partitioning

    PubMed Central

    2009-01-01

    The knowledge base of factors influencing ion pair partitioning is very sparse, primarily because of the difficulty in determining accurate log PI values of desirable low molecular weight (MW) reference compounds. We have developed a potentiometric titration procedure in KCl/water-saturated octanol that provides a link to log PI through the thermodynamic cycle of ionization and partitioning. These titrations have the advantage of being independent of the magnitude of log P, while maintaining a reproducibility of a few hundredths of a log P in the calculated difference between log P neutral and log P ion pair (diff (log PN − I)). Simple model compounds can be used. The titration procedure is described in detail, along with a program for calculating pKa′′ values incorporating the ionization of water in octanol. Hydrogen bonding and steric factors have a greater influence on ion pairs than they do on neutral species, yet these factors are missing from current programs used to calculate log PI and log D. In contrast to the common assumption that diff (log PN − I) is the same for all amines, they can actually vary more than 3 log units, as in our examples. A major factor affecting log PI is the ability of water and the counterion to approach the charge center. Bulky substituents near the charge center have a negative influence on log PI. On the other hand, hydrogen bonding groups near the charge center have the opposite effect by lowering the free energy of the ion pair. The use of this titration method to determine substituent ion pair stabilization values (IPS) should bring about more accurate log D calculations and encourage species-specific QSAR involving log DN and log DI. This work also brings attention to the fascinating world of nature’s highly stabilized ion pairs. PMID:19265385

  13. Influence of the Piping-material-originated Metal-ion on Cell Degradation of Polymer Electrolyte Fuel Cell

    NASA Astrophysics Data System (ADS)

    Amitani, Chieko; Ishikawa, Masahiko; Mori, Kouya; Tanaka, Kenji; Hori, Michio

    Influences of metal-ion adulterations into Polymer Electrolyte Fuel Cells (PEFC) were examined on PEFC generation characteristics and structural changes. Cupper and aluminun, novel candidate materials for forthcoming PEFC system, were introduced into polymer electrolyte membranes (PEM) by ion-exchange method as contaminants, and ca. 500-hour generation tests of PEFC cells with these PEMs were conducted in this study. Introduced metal ions were to be combined to sulfonic acid groups in PEMs by electrostatic forces. For the cell containing cupric ions (Cu2+) equivalent to 1000 pmm of supfonic acid groups in PEM, a decrease in deteriorating rate of cell voltage was observed to be 83 mV/kh during 500-hour generation, in comparison with the cell without metal-ion comtamination showing 154 mV/kh. On the other hand, an increase in deteriorating rates were observed for the cells containing 10 % Cu2+ or 1000 ppm aluminum ions (Al3+). Al3+ adulteration in PEFC set off increases in activation overpotential and fluoride ion release rate (FRR) with proceeding genaration test. An increase in activation overpotentials was supressed in 1000 ppm Cu2+-adulterated cell and the reverse was observed in 10 % Cu2+-adulterated one, though Cu2+ adulterations suppressed growths of platinum catalyst particles in size and FRR regardless of Cu2+ concentration. Restriction effect of 1000 ppm Cu2+-adulteration into PEM on PEFC voltage deterioration has found to be the unprecedented knoledge with respect to PEFC degradation phenomena. Mechanisms of those influences were also discussed.

  14. Influence of gallium ion beam acceleration voltage on the bend angle of amorphous silicon cantilevers

    NASA Astrophysics Data System (ADS)

    Kozeki, Takahiro; Phan, Hoang-Phuong; Viet Dao, Dzung; Inoue, Shozo; Namazu, Takahiro

    2016-06-01

    This paper describes a plastic reshaping technique for Si thin membranes by using focused ion beam (FIB) processing. FIB is used to locally pattern and implant Ga ions into the membranes. The combination of Ga ion doping and alkali wet etching enables us to fabricate nanometer-thick Ga-ion-doped amorphous Si membranes, which can be bent upward at arbitrary angle by controlling the FIB beam irradiation condition. The bending mechanism is discussed in the light of Ga ions implanted depth from the membrane surface. By using this technique, a micrometer-sized chute structure with several different angles is produced.

  15. Influence of target requirements on the production, acceleration, transport, and focusing of ion beams

    SciTech Connect

    Bangerter, R.O.; Mark, J.W.K.; Meeker, D.J.; Judd, D.L.

    1981-01-01

    We have calculated the energy gain of ion-driven fusion targets as a function of input energy, ion range, and focal spot radius. For heavy-ion drivers a given target gain, together with final-lens properties, determines a 6-D phase space volume which must exceed that occupied by the ion beam. Because of Liouville's theorem and the inevitability of some phase space dilutions, the beams's 6-D volume will increase between the ion source and the target. This imposes important requirements on accelerators and on transport and focusing systems.

  16. Influence of ion energies on the structure, composition, and properties of multilayer Ti-Al-Si-N ion-plasma-deposited coatings

    NASA Astrophysics Data System (ADS)

    Blinkov, I. V.; Volkhonskii, A. O.; Belov, D. S.; Sergevnin, V. S.; Chernogor, A. V.

    2016-05-01

    It is established that the energy of deposited particles influences the structure, composition, and properties of multilayer nitride coatings consisting of alternating layers of nanocrystalline TiN and amorphous Si3N4 phases with inclusions of nanocrystalline hexagonal AlN formed at energies of titanium, aluminum, and silicon ions exceeding ~317 × 10-19, 267 × 10-19, and 230 × 10-19 J, respectively. As the energy of titanium ions bombarding the substrate increases above ~512 × 10-19 J, the phase transition from disordered TiN x to Ti3N2 and the appearance of 2- to 3-nm-thick sublayers in 15-nm-thick nanocrystalline TiN x layers take place in the coating. The maximum hardness of such coatings reaches a level of ~54 GPa.

  17. Influence of nuclear interactions in body tissues on tumor dose in carbon-ion radiotherapy

    SciTech Connect

    Inaniwa, T. Kanematsu, N.; Tsuji, H.; Kamada, T.

    2015-12-15

    Purpose: In carbon-ion radiotherapy treatment planning, the planar integrated dose (PID) measured in water is applied to the patient dose calculation with density scaling using the stopping power ratio. Since body tissues are chemically different from water, this dose calculation can be subject to errors, particularly due to differences in inelastic nuclear interactions. In recent studies, the authors proposed and validated a PID correction method for these errors. In the present study, the authors used this correction method to assess the influence of these nuclear interactions in body tissues on tumor dose in various clinical cases. Methods: Using 10–20 cases each of prostate, head and neck (HN), bone and soft tissue (BS), lung, liver, pancreas, and uterine neoplasms, the authors first used treatment plans for carbon-ion radiotherapy without nuclear interaction correction to derive uncorrected dose distributions. The authors then compared these distributions with recalculated distributions using the nuclear interaction correction (corrected dose distributions). Results: Median (25%/75% quartiles) differences between the target mean uncorrected doses and corrected doses were 0.2% (0.1%/0.2%), 0.0% (0.0%/0.0%), −0.3% (−0.4%/−0.2%), −0.1% (−0.2%/−0.1%), −0.1% (−0.2%/0.0%), −0.4% (−0.5%/−0.1%), and −0.3% (−0.4%/0.0%) for the prostate, HN, BS, lung, liver, pancreas, and uterine cases, respectively. The largest difference of −1.6% in target mean and −2.5% at maximum were observed in a uterine case. Conclusions: For most clinical cases, dose calculation errors due to the water nonequivalence of the tissues in nuclear interactions would be marginal compared to intrinsic uncertainties in treatment planning, patient setup, beam delivery, and clinical response. In some extreme cases, however, these errors can be substantial. Accordingly, this correction method should be routinely applied to treatment planning in clinical practice.

  18. Influence of N+ ions on bandgap and electrical resistivity of TiN thin films

    NASA Astrophysics Data System (ADS)

    Singh, Omveer; Dahiya, Raj P.; Malik, Hitendra K.

    2016-05-01

    In the present work, nitrogen ions are embedded into Ti thin films (200 nm) using low energy ion beam implantation (70 keV) by varying ions fluence from 4×1015 ions/cm2 to 2×1016 ions/cm2. For this, Ti films were grown using DC magnetron sputtering in Ar environment (power 200 W). TiN films were then characterized using versatile techniques for estimating the band gap and electrical resistivity. X-ray diffraction pattern shows shift in peaks towards higher angle with increase in nitrogen fluence that confirms the introduction of strain in Ti films. UV-Vis spectra show that band gap is reduced from 3.75 eV to 1.7 eV with increase in fluence from 4×1015 ions/cm2 to 2×1016 ions/cm2. Furthermore, electrical resistivity also decreases from 2.67×10-4 Ω.cm to 2.31×10-4 Ωcm with nitrogen ion fluence. Based on these results, it can be inferred that ion implantation is an effective approach for uniform distribution of N ions in host matrix and tuning of optical and electrical properties.

  19. Influence of the chemical nature of implanted ions on the structure of a silicon layer damaged by implantation

    SciTech Connect

    Shcherbachev, K. D. Voronova, M. I.; Bublik, V. T.; Mordkovich, V. N. Pazhin, D. M.; Zinenko, V. I.; Agafonov, Yu. A.

    2013-12-15

    The influence of the implantation of silicon single crystals by fluorine, nitrogen, oxygen, and neon ions on the distribution of strain and the static Debye-Waller factor in the crystal lattice over the implanted-layer depth has been investigated by high-resolution X-ray diffraction. The density depth distribution in the surface layer of native oxide has been measured by X-ray reflectometry. Room-temperature implantation conditions have ensured the equality of the suggested ranges of ions of different masses and the energies transferred by them to the target. It is convincingly shown that the change in the structural parameters of the radiation-damaged silicon layer and the native oxide layer depend on the chemical activity of the implanted ions.

  20. The influence of ferrous/ferric ions on the efficiency of photocatalytic oxidation of pollutants in groundwater.

    PubMed

    Klauson, D; Preis, S; Portjanskaja, E; Kachina, A; Krichevskaya, M; Kallas, J

    2005-06-01

    The complex influence of ferrous/ferric ions on the efficiency of aqueous photocatalytic oxidation (PCO) of 2-ethoxyethanol (2-EE), methyl tert-butyl ether (MTBE) and humic substances (HS) was established. A drastic efficiency increase at lower concentration of ferrous/ferric ions was observed to change to a sharp decrease at higher concentrations for 2-EE and MTBE, whereas for HS only an inhibitive effect of Fe2+/3+ on the PCO efficiency was noticed. The authors proposed an explanation for the observed phenomena based on the different sensitivities of pollutants towards radical-oxidation reactions and the competitive adsorption of metallic ions and pollutants on the TiO2 surface. PMID:16035658

  1. Des Moines.

    ERIC Educational Resources Information Center

    Gore, Deborah, Ed.

    1988-01-01

    This document, intended for elementary students, contains articles and activities designed to acquaint young people with the history of Des Moines, Iowa. The articles are short, and new or difficult words are highlighted and defined for young readers. "The Raccoon River Indian Agency" discusses the archeological exploration of the indian…

  2. The quantum mechanics of ion-enhanced field emission and how it influences microscale gas breakdown

    SciTech Connect

    Li, Yingjie; Go, David B.

    2014-09-14

    The presence of a positive gas ion can enhance cold electron field emission by deforming the potential barrier and increasing the tunneling probability of electrons—a process known as ion-enhanced field emission. In microscale gas discharges, ion-enhanced field emission produces additional emission from the cathode and effectively reduces the voltage required to breakdown a gaseous medium at the microscale (<10 μm). In this work, we enhance classic field emission theory by determining the impact of a gaseous ion on electron tunneling and compute the effect of ion-enhanced field emission on the breakdown voltage. We reveal that the current density for ion-enhanced field emission retains the same scaling as vacuum cold field emission and that this leads to deviations from traditional breakdown theory at microscale dimensions.

  3. Study of coagulation processes of selected humic acids under copper ions influence*

    NASA Astrophysics Data System (ADS)

    Boguta, Patrycja; Sokolowska, Zofia

    2013-04-01

    Humic acids have limited sorption capacity and big dose of metal or other mineral component which can be sorbed on humic acids, can cause saturation of negative, surface charge of humic acids leading to destabilization of dissolved humic acids compounds. Destabilisation can be observed as coagulation and floculation proces of humic acids. However there are a lot of mechanisms which causing precipitation of humic acids. Thereby, in order to full description of coagulation process, different methods should be applied. Ordinarily, humic acids coagulation is studied by measurement of absorbance, transmittance or carbon loss in solution. Meanwhile, very significant information is also variation of metal content in soil solution and information whether metal goes to precipitate together with humic acids or stays in dissolved form in solution. So, that, from one side, processes of stronger accumulation of metal can lead to soil degradation and micronutrient deficiency for plants. However, there is also possibility to stay metal in solution in toxic and bioavailable form for plants. Main aim of this paper was to study coagulation process of different humic acids extracted from mucking peats under copper ions influence at adjusted pH to 5. In order to this, four peaty-muck soils were taken from selected places in east part of Poland (meadows and river valleys). These soils differed by humification degree, secondary transformation, density and pH. At next step, humic acids were extracted from soils using sodium hydroxide (NaOH) extractant. After exact purification by washing with HF-HCl mixture and water, humic acids were liofilized. Solutions of humic acids were prepared at concentration 40 mg/dm3 with addition of different amount of copper ions to obtain final concentration of Cu(II) ranged from 0-40mg/dm3. After 24 hours solutions were investigated using measurements of absorbance at 470nm (UV-VIS spectrometer Jasco V-530), measurements of organic carbon in solution

  4. Fe(2+) substrate transport through ferritin protein cage ion channels influences enzyme activity and biomineralization.

    PubMed

    Behera, Rabindra K; Torres, Rodrigo; Tosha, Takehiko; Bradley, Justin M; Goulding, Celia W; Theil, Elizabeth C

    2015-09-01

    Ferritins, complex protein nanocages, form internal iron-oxy minerals (Fe2O3·H2O), by moving cytoplasmic Fe(2+) through intracage ion channels to cage-embedded enzyme (2Fe(2+)/O2 oxidoreductase) sites where ferritin biomineralization is initiated. The products of ferritin enzyme activity are diferric oxy complexes that are mineral precursors. Conserved, carboxylate amino acid side chains of D127 from each of three cage subunits project into ferritin ion channels near the interior ion channel exits and, thus, could direct Fe(2+) movement to the internal enzyme sites. Ferritin D127E was designed and analyzed to probe properties of ion channel size and carboxylate crowding near the internal ion channel opening. Glu side chains are chemically equivalent to, but longer by one -CH2 than Asp, side chains. Ferritin D127E assembled into normal protein cages, but diferric peroxo formation (enzyme activity) was not observed, when measured at 650 nm (DFP λ max). The caged biomineral formation, measured at 350 nm in the middle of the broad, nonspecific Fe(3+)-O absorption band, was slower. Structural differences (protein X-ray crystallography), between ion channels in wild type and ferritin D127E, which correlate with the inhibition of ferritin D127E enzyme activity include: (1) narrower interior ion channel openings/pores; (2) increased numbers of ion channel protein-metal binding sites, and (3) a change in ion channel electrostatics due to carboxylate crowding. The contributions of ion channel size and structure to ferritin activity reflect metal ion transport in ion channels are precisely regulated both in ferritin protein nanocages and membranes of living cells. PMID:26202907

  5. The influence of electron irradiation on electron holography of focused ion beam milled GaAs p-n junctions

    SciTech Connect

    Cooper, David; Twitchett-Harrison, Alison C.; Midgley, Paul A.; Dunin-Borkowski, Rafal E.

    2007-05-01

    Electron beam irradiation is shown to significantly influence phase images recorded from focused ion beam milled GaAs p-n junction specimens examined using off-axis electron holography in the transmission electron microscope. Our results show that the use of improved electrical connections to the specimen overcomes this problem, and may allow the correct built in potential across the junction to be recovered.

  6. Complexes of sulfur-containing ligands. I. Factors influencing complex formation between D-penicillamine and copper (II) ion.

    PubMed

    Gergely, A; Sóvágó, I

    1978-07-01

    Complex formation and redox reactions between copper (II) ion and D-penicillamine were studied in detail as functions of the metal/-ligand ratio and the concentration of halide ions. It was established that a copper (I)- D-penicillamine polymeric complex of amphoteric character is formed when excess D-penicillamine is present. When the D-penicillamine/copper (II) ratio = 1.45 in the starting reaction mixture, a mixed valence complex with an intense red-violet color is formed. The formation of this compound, which contains 44% copper (II) ion, is greatly influenced by the experimental conditions, primarily by the concentration of halide ions. The main chemical and physical characteristics of the mixed valence complex were determined via magnetic and spectroscopic measurements. It was further established that a very intense blue complex is formed when the D-penicillamine/copper (II) ratio = 2 and halide ions are present. On the basis of the nature of the products formed under various conditions it was concluded that the copper (II)-D-penicillamine system may serve as a good model for studying the binding sites of copper-containing proteins. PMID:210846

  7. The load and release characteristics on a strong cationic ion-exchange fiber: kinetics, thermodynamics, and influences

    PubMed Central

    Yuan, Jing; Gao, Yanan; Wang, Xinyu; Liu, Hongzhuo; Che, Xin; Xu, Lu; Yang, Yang; Wang, Qifang; Wang, Yan; Li, Sanming

    2014-01-01

    Ion-exchange fibers were different from conventional ion-exchange resins in their non-cross-linked structure. The exchange was located on the surface of the framework, and the transport resistance reduced significantly, which might mean that the exchange is controlled by an ionic reaction instead of diffusion. Therefore, this work aimed to investigate the load and release characteristics of five model drugs with the strong cationic ion-exchange fiber ZB-1. Drugs were loaded using a batch process and released in United States Pharmacopoeia (USP) dissolution apparatus 2. Opposing exchange kinetics, suitable for the special structure of the fiber, were developed for describing the exchange process with the help of thermodynamics, which illustrated that the load was controlled by an ionic reaction. The molecular weight was the most important factor to influence the drug load and release rate. Strong alkalinity and rings in the molecular structures made the affinity between the drug and fiber strong, while logP did not cause any profound differences. The drug–fiber complexes exhibited sustained release. Different kinds and concentrations of counter ions or different amounts of drug–fiber complexes in the release medium affected the release behavior, while the pH value was independent of it. The groundwork for in-depth exploration and further application of ion-exchange fibers has been laid. PMID:25114504

  8. Surface Modification Energized by Focused Ion Beam: The Influence of Etch Rates & Aspect Ratio on Ripple Wavelengths.

    SciTech Connect

    MoberlyChan, W J

    2006-11-15

    Ion beams have been used to modify surface topography, producing nanometer-scale modulations (and even subnanometer ripples in this work) that have potential uses ranging from designing self-assembly structures, to controlling stiction of micromachined surfaces, to providing imprint templates for patterned media. Modern computer-controlled Focused Ion Beam tools enable alternating submicron patterned zones of such ion-eroded surfaces, as well as dramatically increasing the rate of ion beam processing. The DualBeam FIB/SEM also expedites process development while minimizing the use of materials that may be precious (Diamond) and/or produce hazardous byproducts (Beryllium). A FIB engineer can prototype a 3-by-3-by-3 matrix of variables in tens of minutes and consume as little as zeptoliters of material; whereas traditional ion beam processing would require tens of days and tens of precious wafers. Saturation wavelengths have been reported for ripples on materials such as single crystal silicon or diamond ({approx}200nm); however this work achieves wavelengths >400nm on natural diamond. Conversely, Be can provide a stable and ordered 2-dimensional array of <40nm periodicity; and ripples <0.4nm are also fabricated on carbon surfaces and quantified by HR-TEM and electron diffraction. Rippling is a function of material, ion beam, and angle; but is also controlled by chemical environment, redeposition, and aspect ratio. Ideally a material exhibits a constant yield (atoms sputtered off per incident ion); however, pragmatic FIB processes, coupled with the direct metrological feedback in a DualBeam tool, reveal etch rates do not remain constant for nanometer-scale processing. Control of rippling requires controlled metrology, and robust software tools are developed to enhance metrology. In situ monitoring of the influence of aspect ratio and redeposition at the micron scale correlates to the rippling fundamentals that occur at the nanometer scale and are controlled by the

  9. The influence of projectile ion induced chemistry on surface pattern formation

    NASA Astrophysics Data System (ADS)

    Karmakar, Prasanta; Satpati, Biswarup

    2016-07-01

    We report the critical role of projectile induced chemical inhomogeneity on surface nanostructure formation. Experimental inconsistency is common for low energy ion beam induced nanostructure formation in the presence of uncontrolled and complex contamination. To explore the precise role of contamination on such structure formation during low energy ion bombardment, a simple and clean experimental study is performed by selecting mono-element semiconductors as the target and chemically inert or reactive ion beams as the projectile as well as the source of controlled contamination. It is shown by Atomic Force Microscopy, Cross-sectional Transmission Electron Microscopy, and Electron Energy Loss Spectroscopy measurements that bombardment of nitrogen-like reactive ions on Silicon and Germanium surfaces forms a chemical compound at impact zones. Continuous bombardment of the same ions generates surface instability due to unequal sputtering and non-uniform re-arrangement of the elemental atom and compound. This instability leads to ripple formation during ion bombardment. For Argon-like chemically inert ion bombardment, the chemical inhomogeneity induced boost is absent; as a result, no ripples are observed in the same ion energy and fluence.

  10. Influence of Cr-ions on the magnetic behaviour of FeCo film

    NASA Astrophysics Data System (ADS)

    Gupta, Ratnesh; Ansari, Raisa; Khandelwal, Ashish; Fassbender, J.; Gupta, Ajay

    2008-04-01

    Implantation of Cr-ions in Fe70Co30 thin film have been performed to modify its structural and magnetic properties. From the XRD results, the lattice constant as well as the grain size of the film is increasing with the ion fluence. Cr-ions (1 × 1017 ions/cm2) reduces the coercivity of the film from 140(3) Oe to 44(3) Oe. Coercivity of the film follows the exponential decay as a function of Cr-ions fluence. 35 keV (projectile range 13.5 nm) and 100 keV Cr-ions (projectile range 34.3 nm) have been used to understand the effects of magnetic Cr-ions and the effects of ballistic collision cascade on the MOKE signal. Similar changes on the coercivity behaviour of the film implanted with these two energies have been observed. It appears that the implantation process creates a solid solution of Cr in FeCo without any other additional treatment in the film. After 5 × 1016 Cr-ions, film exhibit four fold magnetic anisotropy.

  11. Influence of ion bombardment on the photoluminescence response of embedded CdS nanoparticles

    NASA Astrophysics Data System (ADS)

    Mohanta, Dambarudhar; Singh, Fouran; Avasthi, D. K.; Choudhury, Amarjyoti

    2006-06-01

    Semiconductor nanoparticles (CdS) were fabricated by an inexpensive chemical route using polyvinyl alcohol (PVA) as the dielectric host matrix. Nano-CdS in PVA were subjected to ion irradiation (using oxygen, chlorine and gold) in the medium energy range (80 100 MeV) and under fluence variation of 1011 1013 ions/cm2. The nature of light emission was found to be drastically different in each of the three cases. Photoluminescence spectra of oxygen irradiated samples exhibit band edge emission (2.8 eV) as well as trap related emission (1.76 eV) whereas band edge emission is found to be bleached out for chlorine ion irradiated nano-CdS. The intense broad PL peaks, noticeable in the case of gold ion irradiated samples suggest superposition of the two peaks — namely, band edge emission and trap related emission. Furthermore, in the case of gold ion irradiated nano-CdS, energy shift in the PL spectra reveals variation in size distribution caused by the extra pressure effect of heavy gold ion beams. The mechanism of such a difference as a result of ion irradiation-type and ion-fluence is discussed in detail.

  12. Influence of ion bombardment on the photoluminescence response of embedded CdS nanoparticles

    NASA Astrophysics Data System (ADS)

    Mohanta, Dambarudhar; Singh, Fouran; Avasthi, D.; Choudhury, Amarjyoti

    2006-06-01

    Semiconductor nanoparticles (CdS) were fabricated by an inexpensive chemical route using polyvinyl alcohol (PVA) as the dielectric host matrix. Nano-CdS in PVA were subjected to ion irradiation (using oxygen, chlorine and gold) in the medium energy range (80-100 MeV) and under fluence variation of 1011-1013 ions/cm2. The nature of light emission was found to be drastically different in each of the three cases. Photoluminescence spectra of oxygen irradiated samples exhibit band edge emission (2.8 eV) as well as trap related emission (1.76 eV) whereas band edge emission is found to be bleached out for chlorine ion irradiated nano-CdS. The intense broad PL peaks, noticeable in the case of gold ion irradiated samples suggest superposition of the two peaks — namely, band edge emission and trap related emission. Furthermore, in the case of gold ion irradiated nano-CdS, energy shift in the PL spectra reveals variation in size distribution caused by the extra pressure effect of heavy gold ion beams. The mechanism of such a difference as a result of ion irradiation-type and ion-fluence is discussed in detail.

  13. Influence of radiation reaction force on ultraintense laser-driven ion acceleration.

    PubMed

    Capdessus, R; McKenna, P

    2015-05-01

    The role of the radiation reaction force in ultraintense laser-driven ion acceleration is investigated. For laser intensities ∼10(23)W/cm(2), the action of this force on electrons is demonstrated in relativistic particle-in-cell simulations to significantly enhance the energy transfer to ions in relativistically transparent targets, but strongly reduce the ion energy in dense plasma targets. An expression is derived for the revised piston velocity, and hence ion energy, taking account of energy loses to synchrotron radiation generated by electrons accelerated in the laser field. Ion mass is demonstrated to be important by comparing results obtained with proton and deuteron plasma. The results can be verified in experiments with cryogenic hydrogen and deuterium targets. PMID:26066270

  14. Influence of Ionic Liquids on the Selectivity of Ion Exchange-Based Polymer Membrane Sensing Layers

    PubMed Central

    Mendecki, Lukasz; Callan, Nicole; Ahern, Meghan; Schazmann, Benjamin; Radu, Aleksandar

    2016-01-01

    The applicability of ion exchange membranes is mainly defined by their permselectivity towards specific ions. For instance, the needed selectivity can be sought by modifying some of the components required for the preparation of such membranes. In this study, a new class of materials –trihexyl(tetradecyl)phosphonium based ionic liquids (ILs) were used to modify the properties of ion exchange membranes. We determined selectivity coefficients for iodide as model ion utilizing six phosphonium-based ILs and compared the selectivity with two classical plasticizers. The dielectric properties of membranes plasticized with ionic liquids and their response characteristics towards ten different anions were investigated using potentiometric and impedance measurements. In this large set of data, deviations of obtained selectivity coefficients from the well-established Hofmeister series were observed on many occasions thus indicating a multitude of applications for these ion-exchanging systems. PMID:27438837

  15. Influence of Ionic Liquids on the Selectivity of Ion Exchange-Based Polymer Membrane Sensing Layers.

    PubMed

    Mendecki, Lukasz; Callan, Nicole; Ahern, Meghan; Schazmann, Benjamin; Radu, Aleksandar

    2016-01-01

    The applicability of ion exchange membranes is mainly defined by their permselectivity towards specific ions. For instance, the needed selectivity can be sought by modifying some of the components required for the preparation of such membranes. In this study, a new class of materials -trihexyl(tetradecyl)phosphonium based ionic liquids (ILs) were used to modify the properties of ion exchange membranes. We determined selectivity coefficients for iodide as model ion utilizing six phosphonium-based ILs and compared the selectivity with two classical plasticizers. The dielectric properties of membranes plasticized with ionic liquids and their response characteristics towards ten different anions were investigated using potentiometric and impedance measurements. In this large set of data, deviations of obtained selectivity coefficients from the well-established Hofmeister series were observed on many occasions thus indicating a multitude of applications for these ion-exchanging systems. PMID:27438837

  16. Influence of high energy ion irradiation on the field emission characteristics of CVD diamond films

    NASA Astrophysics Data System (ADS)

    Koinkar, P. M.; Khairnar, R. S.; Khan, S. A.; Gupta, R. P.; Avasthi, D. K.; More, M. A.

    2006-03-01

    The field emission characteristics of ion-irradiated CVD diamond thin film deposited on silicon substrate has been studied. The diamond thin films, synthesized by hot filament chemical vapor deposition (HFCVD) method, were irradiated by high energy (100 MeV) silver ion (107Ag+ with charge state 9) in the fluence range of 3 × 1011-1 × 1013 ions/cm2. The CVD diamond films were characterized by Raman spectroscopy. The Raman spectra of irradiated samples clearly reveal structural damage due to ion irradiation, which is observed to be fluence dependent. However complete graphitization is not observed. The field emission current-voltage (I-V) characteristics were recorded in 'diode' configuration at base pressure ∼1 × 10-8 mbar. Upon ion irradiation the field emission current is observed to increase with the reduction in the threshold voltage, required to draw 1 μA current. The results indicate that ion irradiation leads to better emission characteristics and the structural damage caused by ion irradiation plays a significant role in emission behavior of CVD diamond films.

  17. Influence of ion implantation on the magnetic properties of thin FeCo films

    SciTech Connect

    Gupta, Ratnesh; Han, K.-H.; Lieb, K.P.; Mueller, G.A.; Schaaf, P.; Zhang, K.

    2005-04-01

    Modifications of 73-nm-thick polycrystalline FeCo films by magnetic-field-assisted implantation of Ne, Xe, and Au ions have been investigated. For magnetic characterization, the longitudinal magneto-optic Kerr effect and magnetic force microscopy (MFM) in the remanent state have been used, while structural information has been gained from glancing-angle x-ray diffraction and Rutherford backscattering spectroscopy. The irradiated films show a soft-magnetic behavior with large magnetic anisotropy. The Ne ions initially induce an increasing coercivity, possibly due to radiation defects accumulated during the ion implantation, while higher Ne fluences anneal out the defects and reduce the coercivity. For the heavy ions the deposited energy density is high enough to reduce the coercivity at small fluences and then to increase it slightly for increasing fluence. Correlations between the magnetic anisotropy, coercivity and the ion species and fluence have been established. The MFM pictures feature the largest changes in the case of Au ions. The magnetic anisotropy reflects the interplay between magnetocrystalline and magnetostrictive forces. For heavier ions and large fluences, the direction of the in-plane magnetic easy axis follows the orientation of the external magnetic field present during implantation.

  18. The Influence of the Martian Bow Shock on Heavy Planetary Ions

    NASA Astrophysics Data System (ADS)

    Johnson, B. C.; Liemohn, M. W.; Stenberg, G.; Nilsson, H.; Ramstad, R.; Fraenz, M.

    2014-12-01

    Due to the extent of Mars' exosphere and the large gyroradii of some heavy planetary ions, it is expected that some atmospheric ions will encounter the bow shock. However, the effect that the bow shock has on these heavy ions is relatively unstudied. Mars Express (MEX) ion data is examined to determine whether significant differences exist in the velocity space distributions of energetic planetary ions inside and outside of the shock. To allow for determination of the solar wind motional electric field (Esw) using Mars Global Surveyor (MGS) magnetometer data, the study is focused on the time interval from early 2004 to late 2006 when MEX and MGS overlapped. For each 192 second measurement, an average velocity is assigned to heavy ions at high energies (> 2 keV). The possibility that there is turbulence in the magnetosheath altering the paths of heavy pickup ions will be tested by comparing flight directions relative to the direction of Esw in the magnetosheath to flight directions relative to the Esw direction upstream of the bow shock.

  19. The Influence of Solar Extreme Ultraviolet Radiation on Ring Current Ion Composition: Polar and CRRES Observations

    NASA Astrophysics Data System (ADS)

    Roeder, J. L.; Fennell, J. F.; Pulkkinen, T. I.; Turner, N. E.; Grande, M.

    2001-05-01

    The ion composition observations by the Polar spacecraft from the last solar minimum to the present are compared to similar observations by CRRES in the previous cycle. The Magnetospheric Ion Composition Spectrometer (MICS) was onboard CRRES and is part of the Polar CAMMICE experiment. The MICS sensor provided mass and charge state composition data for the energetic (1-425 keV/q) ions including H+, He+, He++, and O+. The 5-minute average number densities for each species are computed by mapping the MICS fluxes down to the magnetic equator using the measured pitch angle distributions and integrating the equatorial spectrum over the energy range 1-200 keV/q. Approximately 3.5 years of the Polar mission in the rising part of the solar cycle are used for the database. The densities are analyzed statistically with the solar EUV index F10.7 and various geomagnetic indices such as Kp and Dst. The results are compared with a similar study of the ion composition in the energy range 0.9-15.9 keV/q measured by the GEOS 2 satellite during geomagnetically quiet periods [Young et al., 1982], and with the recent survey of the relative composition measured by Polar averaged over all times [Pulkkinen et al., 2000]. It is found that ion densities at L ~ 6-7 during relatively quiet intervals show correlations to the EUV and geomagnetic activity similar to the results of Young et al. [1992]. At lower L the correlation of the ion density with the EUV and activity levels increases substantially, due in part to the extremely low energetic ion densities during the quiet intervals of solar minimum. This may be interpreted as a combination of the solar cycle effects on 1) the ring current source population; and 2) the processes which transport the ions to lower L. The behavior of the ion composition during geomagnetic stormtime is also investigated by restricting the density database to those intervals with the Dst index below a threshold value. Paradoxically, the Polar data shows that the

  20. Graphene oxides prepared by Hummers', Hofmann's, and Staudenmaier's methods: dramatic influences on heavy-metal-ion adsorption.

    PubMed

    Moo, James Guo Sheng; Khezri, Bahareh; Webster, Richard D; Pumera, Martin

    2014-10-01

    Graphene oxide (GO), an up-and-coming material rich in oxygenated groups, shows much promise in pollution management. GO is synthesised using several synthetic routes, and the adsorption behaviour of GO is investigated to establish its ability to remove the heavy-metal pollutants of lead and cadmium ions. The GO is synthesised by Hummers' (HU), Hofmann's (HO) and Staudenmaier's (ST) methodologies. Characterisation of GO is performed before and after adsorption experiments to investigate the structure-function relationship by using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Scanning electron microscopy coupled with elemental detection spectroscopy is used to investigate morphological changes and heavy-metal content in the adsorbed GO. The filtrate, collected after adsorption, is analysed by inductively coupled plasma mass spectrometry, through which the efficiency and adsorption capacity of each GO for heavy-metal-ion removal is obtained. Spectroscopic analysis and characterisation reveal that the three types of GO have different compositions of oxygenated carbon functionalities. The trend in the affinity towards both Pb(II) and Cd(II) is HU GO>HO GO>ST GO. A direct correlation between the number of carboxyl groups present and the amount of heavy-metal ions adsorbed is established. The highest efficiency and highest adsorption capacity of heavy-metal ions is achieved with HU, in which the relative abundance of carboxyl groups is highest. The embedded systematic study reveals that carboxyl groups are the principal functionality responsible for heavy-metal-ion removal in GO. The choice of synthesis methodology for GO has a profound influence on heavy-metal-ion adsorption. A further enrichment of the carboxyl groups in GO will serve to enhance the role of GO as an adsorbent for environmental clean-up. PMID:25044516

  1. Influence of precipitating energetic ions caused by EMIC waves on the subauroral ionospheric E region during a geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Yuan, Zhigang; Xiong, Ying; Li, Haimeng; Huang, Shiyong; Qiao, Zheng; Wang, Zhenzhen; Zhou, Meng; Wang, Dedong; Deng, Xiaohua; Raita, Tero; Wang, Jingfang

    2014-10-01

    In this paper, we have presented the influence of precipitating energetic ions caused by electromagnetic ion cyclotron (EMIC) waves on the subauroral ionospheric E region during a geomagnetic storm on 8 March 2008 with observations of the Meteorological Operational (METOP-02) of the Polar Orbiting Environmental Satellites (POES), a GPS receiver in Vaasa of Finland and Finnish network of search coil magnetometers. Conjugate observations of the POES METOP-02 satellite and Finnish network of search coil magnetometers have demonstrated that enhancements of the precipitating energetic ion flux within the proton anisotropic zone are attributed to the interaction between ring current (RC) ions and EMIC waves. With enhancements of the intensity of Pc1 waves observed by search coil magnetometers, the total electron content observed by the GPS receiver accordingly increased, meaning that the enhancement of the ionospheric electron density is attributed to the precipitation of RC ions caused by EMIC waves. The electron density profiles derived by the International Reference Ionosphere (IRI-2007) model and with precipitating energetic protons observed by the POES METOP-02 satellite show that the energetic proton precipitation can cause the E layer peak electron density to increase from 1.62 × 109 m-3 to 5.05 × 1011 m-3 by 2.49 orders of magnitude. In comparison with the height-integrated conductivities derived by the IRI-2007 model, the height-integrated Pedersen and Hall conductivities derived with precipitating energetic protons increase by 2.4 and 2.34 orders of magnitude, respectively. Our result suggests that precipitating energetic ions caused by EMIC waves can lead to an obvious enhancement of the electron density and conductivities in the subauroral ionospheric E region during geomagnetic storms.

  2. Influence of persulfate ions on the removal of phenol in aqueous solution using electron beam irradiation.

    PubMed

    Boukari, Sahidou O B; Pellizzari, Fabien; Karpel Vel Leitner, Nathalie

    2011-01-30

    The removal of phenol (Co = 100 μM) during electron beam irradiation was studied in pure water and in the presence of HCO(3)(-) and Br(-) ions. It was found that the introduction of S(2)O(8)(2-) ions (1mM), by generating SO(4)(-) radicals increases the radiation yield of phenol removal. 90% removal of phenol was obtained with radiation doses 600 and 1200 Gy with and without S(2)O(8)(2-) ions respectively. This system induced smaller oxygen consumption with smaller concentration of catechol and hydroquinone found in the solution. HCO(3)(-) and Br(-) have an inhibiting effect in the presence as in the absence of S(2)O(8)(2-). In most cases, the introduction of S(2)O(8)(2-) ions in water radiolysis system can advantageously increase the yield of organic compounds removal by oxidation. PMID:21093981

  3. Influence of Si ion implantation on structure and morphology of g-C3N4

    NASA Astrophysics Data System (ADS)

    Varalakshmi, B.; Sreenivasulu, K. V.; Asokan, K.; Srikanth, V. V. S. S.

    2016-07-01

    Effect of Si ion implantation on structural and morphological features of graphite-like carbon nitride (g-C3N4) was investigated. g-C3N4 was prepared by using a simple atmospheric thermal decomposition process. The g-C3N4 pellets were irradiated with a Si ion beam of energy 200 keV with different fluencies. Structural, morphological and elemental, and phase analysis of the implanted samples in comparison with the pristine samples was carried out by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) with energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) techniques, respectively. The observations revealed that Si ion implantation results in a negligible change in the crystallite size and alteration of the network-like to the sheet-like morphology of g-C3N4 and Si ions in the g-C3N4 network.

  4. Removal of heavy metal ions by biogenic hydroxyapatite: Morphology influence and mechanism study

    NASA Astrophysics Data System (ADS)

    Wang, Dandan; Guan, Xiaomei; Huang, Fangzhi; Li, Shikuo; Shen, Yuhua; Chen, Jun; Long, Haibo

    2016-08-01

    Based on the synthesis of hydroxyapatite (HA) with different morphologies, such as nanorod-like, flower-like and sphere-like assembled HA nanorods, a new strategy has been developed for the removal of heavy metal ions such as Pb2+, Cu2+, Mn2+, Zn2+. The dependence of removal efficiency on the morphology and the suspended concentration of trapping agent, the removal time and selectivity were evaluated and discussed. The experimental results proved that the removal capacity of flower-like assembled HA nanorods (NAFL-HA) was the best, and the maximum removal ratio for Pb2+ ion was 99.97%. The mechanism of Pb2+ removal was studied in detail, noting that some metal ions were completely incorporated into hydroxyapatitie to produce Pb-HA. It reveals that the metal ions capture by HA is mainly controlled by sample surface adsorption and co-precipitation, which are directly controlled by sample morphology.

  5. Influence of Temperature on Nitrogen Ion Implantation of Ti6Al4V Alloy

    NASA Astrophysics Data System (ADS)

    Zhao, Qing; Zheng, Yong-zhen; Mo, Zhi-tao; Tang, De-li; Tong, Hong-hui; Geng, Man

    2001-04-01

    In order to achieve increased layer thickness, and wearing resistance, enhanced ion implantation with nitrogen has been carried out at temperatures of 100, 200, 400, and 600°C with a dose of 4×1018 ions cm-2. Using the Plasma Source Ion Implantation (PSII) device, specimens of Ti6Al4V alloy were implanted at elevated temperatures, using the ion flux as the heating source. Auger Electron Spectroscopy (AES), Scanning Electron Microscopy (SEM), x-ray Diffraction (XRD), micro-hardness measurements and pin-on-disk wearing tester were utilized to evaluate the surface property improvements. The thickness of the implanted layer increased by about an order of magnitude when the temperature was elevated from 100 to 600°C. Higher surface hardness and wearing resistance was also obtained in implantation under higher temperature. XRD image showed the presence of titanium nitrides on the implanted surface.

  6. Influence of laser pulse duration on extreme ultraviolet and ion emission features from tin plasmas

    SciTech Connect

    Roy, A. E-mail: aroy@barc.gov.in; Harilal, S. S.; Polek, M. P.; Hassan, S. M.; Hassanein, A.; Endo, A.

    2014-03-15

    We investigated the role of laser pulse duration and intensity on extreme ultraviolet (EUV) generation and ion emission from a laser produced Sn plasma. For producing plasmas, planar slabs of pure Sn were irradiated with 1064 nm Nd:YAG laser pulses with varying pulse duration (5–20 ns) and intensity. Experimental results performed at CMUXE indicate that the conversion efficiency (CE) of the EUV radiation strongly depend on laser pulse width and intensity, with a maximum CE of ∼2.0% measured for the shortest laser pulse width used (5 ns). Faraday Cup ion analysis of Sn plasma showed that the ion flux kinetic profiles are shifted to higher energy side with the reduction in laser pulse duration and narrower ion kinetic profiles are obtained for the longest pulse width used. However, our initial results showed that at a constant laser energy, the ion flux is more or less constant regardless of the excitation laser pulse width. The enhanced EUV emission obtained at shortest laser pulse duration studied is related to efficient laser-plasma reheating supported by presence of higher energy ions at these pulse durations.

  7. Influence of ion source configuration and its operation parameters on the target sputtering and implantation process.

    PubMed

    Shalnov, K V; Kukhta, V R; Uemura, K; Ito, Y

    2012-06-01

    In the work, investigation of the features and operation regimes of sputter enhanced ion-plasma source are presented. The source is based on the target sputtering with the dense plasma formed in the crossed electric and magnetic fields. It allows operation with noble or reactive gases at low pressure discharge regimes, and, the resulting ion beam is the mixture of ions from the working gas and sputtering target. Any conductive material, such as metals, alloys, or compounds, can be used as the sputtering target. Effectiveness of target sputtering process with the plasma was investigated dependently on the gun geometry, plasma parameters, and the target bias voltage. With the applied accelerating voltage from 0 to 20 kV, the source can be operated in regimes of thin film deposition, ion-beam mixing, and ion implantation. Multi-component ion beam implantation was applied to α-Fe, which leads to the surface hardness increasing from 2 GPa in the initial condition up to 3.5 GPa in case of combined N(2)-C implantation. Projected range of the implanted elements is up to 20 nm with the implantation energy 20 keV that was obtained with XPS depth profiling. PMID:22755619

  8. Influence of ion source configuration and its operation parameters on the target sputtering and implantation process

    SciTech Connect

    Shalnov, K. V.; Kukhta, V. R.; Uemura, K.; Ito, Y.

    2012-06-15

    In the work, investigation of the features and operation regimes of sputter enhanced ion-plasma source are presented. The source is based on the target sputtering with the dense plasma formed in the crossed electric and magnetic fields. It allows operation with noble or reactive gases at low pressure discharge regimes, and, the resulting ion beam is the mixture of ions from the working gas and sputtering target. Any conductive material, such as metals, alloys, or compounds, can be used as the sputtering target. Effectiveness of target sputtering process with the plasma was investigated dependently on the gun geometry, plasma parameters, and the target bias voltage. With the applied accelerating voltage from 0 to 20 kV, the source can be operated in regimes of thin film deposition, ion-beam mixing, and ion implantation. Multi-component ion beam implantation was applied to {alpha}-Fe, which leads to the surface hardness increasing from 2 GPa in the initial condition up to 3.5 GPa in case of combined N{sub 2}-C implantation. Projected range of the implanted elements is up to 20 nm with the implantation energy 20 keV that was obtained with XPS depth profiling.

  9. Stability Dust-Ion-Acoustic Wave In Dusty Plasmas With Stream -Influence Of Charge Fluctuation Of Dust Grains

    SciTech Connect

    Atamaniuk, Barbara; Zuchowski, Krzysztof

    2006-01-15

    There is a quickly increasing wealth of experimental data on so-called dusty plasmas i. e. ionized gases or usual plasmas that contain micron sized charged particles. Interest in these structures is driven both by their importance in many astrophysical as well as commercial situations. Among them are linear and nonlinear wave phenomena. We consider the influence of dust charge fluctuations on stability of the ion-acoustic waves when the stream of particles is present. It is assumed that all grains of dust have equal masses but charges are not constant in time-they may fluctuate in time. The dust charges are not really independent of the variations of the plasma potentials. All modes will influence the charging mechanism, and feedback will lead to several new interesting and unexpected phenomena. The charging of the grains depends on local plasma characteristics. If the waves disturb these characteristic, then charging of the grains is affected and the grain charge is modified, with a resulting feedback on the wave mode. In case considering here, when temperature of electrons is much greater then the temperature of the ions and temperature of electrons is not great enough for further ionization of the ions, we show that stability of the acoustic wave depends only one phenomenological coefficient.

  10. Influence of Amino Acid Composition and Phosphorylation on the Ion Yields of Peptides in MALDI-MS

    NASA Astrophysics Data System (ADS)

    Asakawa, Daiki; Moriguchi, Shohey; Takayama, Mitsuo

    2012-01-01

    The influence of arginine (Arg), lysine (Lys), and phenylalanine (Phe) residues and phosphorylation on the molecular ion yields of model peptides have been quantitatively studied using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry in both positive- and negative-ion mode. The results obtained from these experiments have been interpreted from the standpoint of two different components, namely, desorption and ionization, on the basis of the physicochemical properties of constituent amino acids of the model peptides. The presence of basic residues such as Arg and Lys enhanced the ion yields of protonated molecules [M + H]+. An N-terminal rather than a C-terminal Arg residue was advantageous for the formation of both [M + H]+ and [M - H]-. The presence of the Phe residue resulted in the increase of the ion yields of both [M + H]+ and [M - H]-. In contrast, the presence of phosphate group(s) contributed to the suppression of the yields of both [M + H]+ and [M - H]- due to the loss of phosphate group. The detection limits for both [M + H]+ and [M - H]- of model peptides have been evaluated.

  11. The influence of dose, dose-rate and particle fragmentation on cataract induction by energetic iron ions

    NASA Astrophysics Data System (ADS)

    Medvedovsky, C.; Worgul, B. V.; Huang, Y.; Brenner, D. J.; Tao, F.; Miller, J.; Zeitlin, C.; Ainsworth, E. J.

    1994-10-01

    Because activities in space necessarily involve chronic exposure to a heterogeneous charged particle radiation field it is important to assess the influence of dose-rate and the possible modulating role of heavy particle fragmentation on biological systems. Using the well-studied cataract model, mice were exposed to plateau 600 MeV/amu 56Fe ions either as acute or fractionated exposures at total doses of 5 - 504 cGy. Additional groups of mice received 20, 360 and 504 cGy behind 50 mm of polyethylene, which simulates body shielding. The reference radiation consisted of 60Co γ radiation. The animals were examined by slit lamp biomicroscopy over their three year life spans. In accordance with our previous observations with heavy particles, the cataractogenic potential of the 600 MeV/amu 56Fe ions was greater than for low-LET radiation and increased with decreasing dose relative to γ-rays. Fractionation of a given dose of 56Fe ions did not reduce the cataractogenicity of the radiation compared to the acute regimen. Fragmentation of the beam in the polyethylene did not alter the cataractotoxicity of the ions, either when administered singly or in fractions.

  12. The influence of dose, dose-rate and particle fragmentation on cataract induction by energetic iron ions

    NASA Technical Reports Server (NTRS)

    Medvedovsky, C.; Worgul, B. V.; Huang, Y.; Brenner, D. J.; Tao, F.; Miller, J.; Zeitlin, C.; Ainsworth, E. J.

    1994-01-01

    Because activities in space necessarily involve chronic exposure to a heterogeneous charged particle radiation field it is important to assess the influence of dose-rate and the possible modulating role of heavy particle fragmentation on biological systems. Using the well-studied cataract model, mice were exposed to plateau 600 MeV/amu Fe-56 ions either as acute or fractionated exposures at total doses of 5-504 cGy. Additional groups of mice received 20, 360 and 504 cGy behind 50 mm of polyethylene, which simulates body shielding. The reference radiation consisted of Co-60 gamma radiation. The animals were examined by slit lamp biomicroscopy over their three year life spans. In accordance with our previous observations with heavy particles, the cataractogenic potential of the 600 MeV/amu Fe-56 ions was greater than for low-Linear Energy Transfer (LET) radiation and increased with decreasing dose relative to gamma rays. Fractionation of a given dose of Fe-56 ions did not reduce the cataractogenicity of the radiation compared to the acute regimen. Fragmentation of the beam in the polyethylene did not alter the cataractotoxicity of the ions, either when administered singly or in fractions.

  13. Influence des paramètres de dépôt sur la morphologie de films minces de tétraborate de lithium obtenus par le procédé ``PYROSOL"

    NASA Astrophysics Data System (ADS)

    Bornand, V.; El Bouchikhi, A.; Papet, Ph.; Philippot, E.

    1997-04-01

    Li2B4O7 piezo-electric thin films were prepared by “PYROSOL" process which is a useful method for the elaboration of thin films. Morphological development and crystallization of thin films are very dependent on the experimental parameters like the substrate temperature, the concentration and the relative proportion of the precursors in methyl alcohol. The effect of these various parameters were studied in order to obtain homogeneous, crystallized and oriented thin films. La réalisation de couches minces de matériaux piézo-électriques de Li2B4O7 par le procédé “PYROSOL" révèle une grande diversité de conditions de dépôt. La température du substrat, la composition des solutions de précurseurs et leur concentration conditionnent la morphologie et l'état de cristallisation des films. En particulier, l'obtention de couches minces denses, homogènes et présentant une orientation préférentielle nécessite des températures de substrat supérieures à 620 ^{circ}C. L'influence de ces divers paramètres expérimentaux a été étudiée dans le but d'obtenir des dépôts homogènes, cristallisés et orientés.

  14. Influence of Ar + ion bombardment on the initial interaction of water vapour with polycrystalline magnesium surfaces

    NASA Astrophysics Data System (ADS)

    Splinter, S. J.; McIntyre, N. S.; Palumbo, G.

    1994-01-01

    The room temperature interaction of water vapour with magnesium surfaces irradiated with Ar + ions in the dose range θ = 10 to 2000 ions/surface atom and ion energy range 1 to 5 keV has been systematically studied by Auger electron spectroscopy (AES). The character of the kinetics of water interaction with irradiated surfaces has been found to be dependent upon the total ion bombardment dose and the ion energy and to change with the level of water exposure. The effect of ion bombardment was found to be most pronounced in the oxide nucleation and growth stage of the oxidation process. The dissociative chemisorption and final bulk thickening regimes were only weakly affected by prior irradiation. The results have been interpreted based on the assumption of competition between the effects of radiation defects (vacancies, vacancy clusters, dislocation loops) and implanted argon atoms on the oxidation process. The effect of vacancy-type defects was speculated to be the provision of adsorption sites of high sticking probability and nucleation sites of reduced activation energy for place exchange and subsequent island growth. The effect of implanted argon atoms was speculated to be the blocking of adsorption and nucleation sites and interference with oxide island ordering. At relatively high water exposures (20 L) there was enhanced penetration of oxygen into the magnesium lattice postulated to occur along dislocation emergence points. No such enhanced penetration was observed for shorter water exposures (0.3 L). The limiting thickness of the oxide layer formed on magnesium at room temperature was not found to be affected by the level of prior ion bombardment.

  15. Influence of tungsten microstructure and ion flux on deuterium plasma-induced surface modifications and deuterium retention

    NASA Astrophysics Data System (ADS)

    Buzi, L.; De Temmerman, G.; Unterberg, B.; Reinhart, M.; Dittmar, T.; Matveev, D.; Linsmeier, Ch.; Breuer, U.; Kreter, A.; Van Oost, G.

    2015-08-01

    The influence of surface temperature, particle flux density and material microstructure on the surface morphology and deuterium retention was studied by exposing tungsten targets (20 μm and 40 μm grain size) to deuterium plasma at the same particle fluence (1026 m-2) and incident ion energy (40 eV) to two different ion fluxes (low flux: 1022 m-2 s-1, high flux: 1024 m-2 s-1). The maximum of deuterium retention was observed at ∼630 K for low flux density and at ∼870 K for high flux density, as indicated from the thermal desorption spectroscopy data (TDS). Scanning electron microscopy observations revealed the presence of blisters with a diameter of up to 1 μm which were formed at high flux density and high temperature (1170 K) contrasting with previously reported surface modification results at such exposure conditions.

  16. Features of relief formation of the polycrystalline samples under the influence of a wide-aperture ion beam

    NASA Astrophysics Data System (ADS)

    Yashin, A. S.

    2016-04-01

    The results of investigation of the cylindrical surface state after influence of wide- aperture ion beam are presented in this paper. Experiments were carried out on the parts of cladding tubes from E110 alloy (Zr-1%Nb) up to 500 mm length. The outer surface of the tubes was treated by Ar+ ions with energy 0.1-1.0 keV up to doses (1-10)× 1018 cm-2 on the installation KVK-10. Due to design features of the installation, the angle of incidence of particles on the surface varied from 0 to 90°. It is found that as a result of treatment made, smoothed relief of the surface forms and uniformity of near-surface layer structure improves. The statistical method suggested allowed to reveal features of the polycrystalline samples surface state with random and regular components, based on the results of profilograms analysis.

  17. The influence of different metal ions on light scattering properties of pattern microbial fuel cells' bacteria Desulfuromonas acetoxidans

    NASA Astrophysics Data System (ADS)

    Vasyliv, Oresta M.; Bilyy, Olexsandr I.; Getman, Vasyl'B.; Ferensovyich, Yaroslav P.; Yaremyk, Roman Y.; Hnatush, Svitlana O.

    2011-09-01

    Microbial fuel cell (MFC) technologies represent the newest approach for generating electricity - bioelectricity generation from biomass using bacteria. Desulfuromonas acetoxidans are aquatic obligatory anaerobic sulfur-reducing bacteria that possess an ability to produce electric current in the processes of organic matter oxidation and Fe3+- or Mn4+- reduction. These are pattern objects for MFC systems. They could be applied as a highly effective and self-sustaining model of wastewater treatment which contains energy in the form of biodegradable organic matter. But wastewaters contain high concentrations of xenobiotics, such as different heavy metals that have a detrimental effect towards all living organisms. The influence of different concentrations of MnCl2×4H2O, FeSO4 CuSO4, CdSO4, ZnSO4 and PbNO3 on light scattering properties of aquatic D. acetoxidans bacteria on the base of their cells' size distribution and relative content has been investigated by the new method of measurement. The cell distribution curve was in the range of 0.4 - 1.4 μm. The most crucial changes of cell concentration dependences, compared with other investigated metal ions, have been observed under the influence of copper ions. The ability of D. acetoxidans bacteria to produce electric current upon the specific cultivation conditions and the influence of Fe2+ and Mn2+ has been verified.

  18. Investigations into the Influence of Heavy Ions on EMIC Wave Propagation in the Earth's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Keller, S.; Kim, E. H.; Johnson, J.

    2015-12-01

    Geomagnetic pulsations in the Pc1 frequency range (0.2 to 5.0 Hz), which are known as electromagnetic ion cyclotron (EMIC) waves, are often observed at magnetically conjugate locations by spacecraft in the equatorial magnetosphere and ground-based stations. One difficulty in linking the propagation of detected radiation between these regions is the presence of stop bands near the heavy ion cyclotron resonance locations. Recent full wave calculations (Kim and Johnson, Full wave modeling of EMIC waves in the Earth's magnetosphere, 2015 AGU fall meeting) demonstrate how EMIC waves propagate to higher magnetic latitudes in an electron-proton-He+ plasma. However, while the heavy ion concentration can be large during the solar maximum and geomagnetic storms, they adopted a 5% He+ plasma. In this study, we explore the roles of heavy ion (He+ and O+) concentrations on the levels of EMIC wave energy that reach lower altitudes using a two-dimensional, finite element, full wave model. The Poynting flux and polarization of the emissions are used to monitor the propagation and absorption of wave energy, as well as mode coupling between left- and right-hand circularly polarized modes. Due to the increase in heavy ion populations in the magnetosphere, the consequences that geomagnetic storms have on EMIC wave propagation are also discussed.

  19. Influence of hot beam ions on MHD ballooning modes in tokamaks

    SciTech Connect

    Rewoldt, G.; Tang, W.M.

    1984-07-01

    It has recently been proposed that the presence of high energy ions from neutral beam injection can have a strong stabilizing effect on kinetically-modified ideal MHD ballooning modes in tokamaks. In order to assess realistically the importance of such effects, a comprehensive kinetic stability analysis, which takes into account the integral equation nature of the basic problem, has been applied to this investigation. In the collisionless limit, the effect of adding small fractions of hot beam ions is indeed found to be strongly stabilizing. On the other hand, for somewhat larger fractions of hot ions, a new beam-driven mode is found to occur with a growth rate comparable in magnitude to the growth rate of the MHD ballooning mode in the absence of hot ions. This implies that there should be an optimal density of hot particles which minimizes the strength of the relevant instabilities. Employing non-Maxwellian equilibrium distribution functions to model the beam species makes a quantitative, but not qualitative, difference in the results. Adding collisions to the calculation tends to reduce considerably the stabilizing effect of the hot ions.

  20. Influence of irradiation spectrum and implanted ions on the amorphization of ceramics

    SciTech Connect

    Zinkle, S.J.; Snead, L.L.

    1996-04-01

    Amorphization cannot be tolerated in ceramics proposed for fusion energy applications due to the accompanying large volume change ({approx} 15% in SiC) and loss of strength. Ion beam irradiations at temperatures between 200 K and 450 K were used to examine the likelihood of amorphization in ceramics being considered for the structure (SiC) and numerous diagnostic and plasma heating systems (MgAl{sub 2}O{sub 4}, Al{sub 2}O{sub 3}, MgO, Si{sub 3}N{sub 4}) in fusion energy systems. The microstructures were examined following irradiation using cross-section transmission electron microscopy. The materials in this study included ceramics with predominantly covalent bonding (SiC, Si{sub 3}N{sub 4}) and predominantely ionic bonding (MgAl{sub 2}O{sub 4}, Al{sub 2}O{sub 3}, MgO). The samples were irradiated with a variety of ion beams (including some simultaneous dual ion beam irradiations) in order to investigate possible irradiation spectrum effects. The ion energies were >0.5 MeV in all cases, so that the displacement damage effects could be examined in regions well separated from the implanted ion region.

  1. Influence of electronic energy deposition on the structural modification of swift heavy-ion-irradiated amorphous germanium layers

    SciTech Connect

    Steinbach, T.; Schnohr, C. S.; Wesch, W.; Kluth, P.; Giulian, R.; Araujo, L. L.; Sprouster, D. J.; Ridgway, M. C.

    2011-02-01

    Swift heavy-ion (SHI) irradiation of amorphous germanium (a-Ge) layers leads to a strong volume expansion accompanied by a nonsaturating irreversible plastic deformation (ion hammering), which are consequences of the high local electronic energy deposition within the region of the a-Ge layer. We present a detailed study of the influence of SHI irradiation parameters on the effect of plastic deformation and structural modification. Specially prepared a-Ge layers were irradiated using two SHI energies and different angles of incidence, thus resulting in a variation of the electronic energy deposition per depth {epsilon}{sub e} between 14.0 and 38.6 keV nm{sup -1}. For all irradiation parameters used a strong swelling of the irradiated material was observed, which is caused by the formation and growth of randomly distributed voids, leading to a gradual transformation of the amorphous layer into a sponge-like porous structure as established by cross-section scanning electron microscopy investigations. The swelling depends linearly on the ion fluence and on the value of {epsilon}{sub e}, thus clearly demonstrating that the structural changes are determined solely by the electronic energy deposited within the amorphous layer. Plastic deformation shows a superlinear dependence on the ion fluence due to the simultaneous volume expansion. This influence of structural modification on plastic deformation is described by a simple approach, thus allowing estimation of the deformation yield. With these results the threshold values of the electronic energy deposition for the onset of both structural modification and plastic deformation due to SHI irradiation are determined. Furthermore, based on these results, the longstanding question concerning the reason for the structural modification observed in SHI-irradiated crystalline Ge is answered.

  2. Influence of argon and oxygen on charge-state-resolved ion energydistributions of filtered aluminum arcs

    SciTech Connect

    Rosen, Johanna; Anders, Andre; Mraz, Stanislav; Atiser, Adil; Schneider, Jochen M.

    2006-03-23

    The charge-state-resolved ion energy distributions (IEDs) in filtered aluminum vacuum arc plasmas were measured and analyzed at different oxygen and argon pressures in the range 0.5 8.0 mTorr. A significant reduction of the ion energy was detected as the pressure was increased, most pronounced in an argon environment and for the higher charge states. The corresponding average charge state decreased from 1.87 to 1.0 with increasing pressure. The IEDs of all metal ions in oxygen were fitted with shifted Maxwellian distributions. The results show that it is possible to obtain a plasma composition with a narrow charge-state distribution as well as a narrow IED. These data may enable tailoring thin-film properties through selecting growth conditions that are characterized by predefined charge state and energy distributions.

  3. Influence of air ions on brain activity induced by electrical stimulation in the rat

    NASA Astrophysics Data System (ADS)

    Olivereau, J. M.; Lambert, J. F.; Truong-Ngoc, A.

    1981-03-01

    The brain induced activity was studied in 18 rats wearing chronically skull implanted electrodes. The stimulating factor was various electrical stimulations of the mesencephalic reticular activating formation, given during the slow wave state of sleep. The results of 300 stimulations were measured by amplitude and frequency changes in the EEG simultaneously recorded. Animals previously exposed to positive air ions (3 weeks 80,000 ions/ml) exhibited lowered excitability of the reticulocortical system. Significantly higher stimulations were necessary to induce arousal. Negative air ions induced more intricate effects: brain excitability was lowered when tested with weak stimulations, but normal when evaluated with medium high level stimilations. Sleep seems first more stable but as stimulation increases, arousal is soon as effective as in controls. These results are in agreement with others findings in behavioral fields and partly explains them.

  4. Theory of Resonance Influence of Sawtooth Crashes on Ions with Large Orbit Width

    SciTech Connect

    R.B. White; V.V. Lutsenko; Y.I. Kolesnichenko; Y.V. Yakovenko

    1998-02-01

    The role of resonances in the sawtooth-crash-induced redistribution of fast ions is investigated. In particular, the conditions of wave-particle resonant interaction in the presence of the equilibrium electric field and the mode rotation are obtained, and effects of sawteeth on the resonant particles with arbitrary width of non-perturbed orbits are studied. It is found that resonances play the dominant role in the transport of ions having sufficiently high energy. It is shown that the resonance regions may overlap, in which case the resonant particles may constitute the main fraction of the fast ion population in the sawtooth mixing region. The behavior of the resonant particles is studied both by constructing a Poincaré map and analytically, by means of the adiabatic invariant derived in this paper and calculation of the characteristic frequencies of the particle motion.

  5. Study of the influence of surface carbon on the tribological properties of ion-treated steels

    NASA Astrophysics Data System (ADS)

    Benyagoub, Abdenacer; Faussemagne, Arielle

    1999-01-01

    Samples of 100Cr6 steel were treated by different ion beams in order to study the evolution of their tribological properties. A strong correlation was found between the amount of surface carbon, whatever its origin (contamination, direct C implantation or ion-beam mixing of a deposited carbon layer), and the reduction of the friction coefficient as well as the improvement of the wear resistance. These results are discussed in the framework of a recent statistical model founded on the asperity concept and describing the tribological behaviour of bilayer systems.

  6. Influence of annular magnet on discharge characteristics in enhanced glow discharge plasma immersion ion implantation

    SciTech Connect

    Li Liuhe; Wang Zhuo; Lu Qiuyuan; Fu, Ricky K. Y.; Chu, Paul K.; Pang Enjing; Dun Dandan; He Fushun; Li Fen

    2011-01-10

    A permanent annular magnet positioned at the grounded anode alters the discharge characteristics in enhanced glow discharge plasma immersion ion implantation (EGD-PIII). The nonuniform magnetic field increases the electron path length and confines electron motion due to the magnetic mirror effect and electron-neutral collisions thus occur more frequently. The plasma potential and ion density measured by a Langmuir probe corroborate that ionization is improved near the grounded anode. This hybrid magnetic field EGD-PIII method is suitable for implantation of gases with low ionization rates.

  7. Influence of ageing on Raman spectra and the conductivity of monolayer graphene samples irradiated by heavy and light ions

    NASA Astrophysics Data System (ADS)

    Butenko, A.; Zion, E.; Kaganovskii, Yu.; Wolfson, L.; Richter, V.; Sharoni, A.; Kogan, E.; Kaveh, M.; Shlimak, I.

    2016-07-01

    The influence of long-term ageing (about one year) on the Raman scattering (RS) spectra and the temperature dependence of conductivity has been studied in two series of monolayer graphene samples irradiated by different doses of C+ and Xe+ ions. It is shown that the main result of ageing consists of changes in the intensity and position of D- and G- and 2D-lines in RS spectra and in an increase of the conductivity. The observed effects are explained in terms of an increase of the radius of the "activated" area around structural defects.

  8. Nd{sup 3+} and Am{sup 3+} ion interactions with sulfate ion and their influence on NdPO{sub 4}(c) solubility

    SciTech Connect

    Rai, D.; Felmy, A.R.; Fulton, R.W.

    1995-09-01

    The effects of Nd(III)/Am(III) complexation with sulfate were studied by (1) re-examining existing data for the Am-SO{sub 4} system using more advanced aqueous electrolyte models valid to high concentration to obtain reliable thermodynamic data for SO{sub 4}{sup 2{minus}} complexes or ion interactions with Nd{sup 3+} and Am{sup 3+} and (2) conducting experimental solubility studies of NdPO{sub 4}(c), an analog phase of AmPO{sub 4}(c), a possibly important phase in high level nuclear wastes, in the presence of SO{sub 4}{sup 2{minus}} to test the newly developed thermodynamic model and show the possible influence of sulfate in a repository environment. The data showed that the increase in the solubility of NdPO{sub 4}(c) resulted primarily from the increase in ionic strength. Slightly higher observed Nd concentrations in the presence of sulfate, as compared with concentrations predicted at the experimental ionic strengths, resulted from the weak complexes or ion interactions involving Nd{sup 3+}-SO{sub 4}{sup 2{minus}}. The Pitzer ion interaction parameters, applicable to 0.5m sulfate, were obtained for Am{sup 3+}-SO{sub 4}{sup 2{minus}} from a reinterpretation of known solvent extraction data. These parameters are also consistent with literature data for Am{sup 3+}/Na{sup +} exchange and solvent extraction in the presence of sulfate. When used for the analogous Nd{sup 3+}-SO{sub 4}{sup 2{minus}} system to predict NdPO{sub 4}(c) solubility in the presence of sulfate, they provided excellent agreement between the predicted and the observed solubilities, indicating that they can be reliably used to determine Nd{sup 3+} or Am{sup 3+} ion interactions with SO{sub 4}{sup 2-} in all ground waters where SO{sub 4}{sup 2{minus}} is less than 0.5 m.

  9. Constantes de stabilité de complexes organo-minéraux. Interactions des ions plombeux avec les composés organiques hydrosolubles des eaux gravitaires de podzol

    NASA Astrophysics Data System (ADS)

    Bizri, Y.; Cromer, M.; Scharff, J. P.; Guillet, B.; Rouiller, J.

    1984-02-01

    The complexation of lead(II) ions by water-soluble soil organic matter as ligand (recovered by percolating water through a A2 horizon of a podzolic soil) has been studied by potentiometric methods at 25°C in 0.1 M NaClO 4 medium. The total acidity of these solutions was resolved into strong, weak and very weak acidity. During the alkali titration, the dissociation of humic samples was characterized by an α coefficient that may be determined according to a procedure derived from Irving-Rossotti's method. The so-called Henderson-Hasselbalch equation was used to obtain pK A values for each of the two weak acidities ( pKA = 4.80 (COOH) and pKA = 8.85 (OH)). For the determination of stability constants of metal-humate complexes (HA) in the acidic range, three methods have been investigated: - an approach using only pH measurements. - direct estimation of the free metal ion concentrations from ISE determinations. - application of Marinsky's method accounting for complications arising from the electric field at the surface of the polyelectrolyte which determines the effective concentration [A]. In these experiments typical values used for total lead(II) ion concentrations and total ligand concentrations are respectively in the range 4.10 -5 M to 4.10 -4 M and 0,33 to 0,57 meq·1 -1. All results agree with the existence of mono and bis-complexes PbA and PbA 2 with stability constants (protometric determinations): logK1 = 4.2 and logK2 = 3.7. The values obtained by direct estimation of free lead(II) concentration are slightly lower. An increase in stability constants was observed with increase in pH and also with decrease in total metal ion concentration (at constant pH). Ligand conformational properties are expected to be of great importance in the complexation phenomena.

  10. Modeling the Influence of Ion Channels on Neuron Dynamics in Drosophila

    PubMed Central

    Berger, Sandra D.; Crook, Sharon M.

    2015-01-01

    Voltage gated ion channels play a major role in determining a neuron's firing behavior, resulting in the specific processing of synaptic input patterns. Drosophila and other invertebrates provide valuable model systems for investigating ion channel kinetics and their impact on firing properties. Despite the increasing importance of Drosophila as a model system, few computational models of its ion channel kinetics have been developed. In this study, experimentally observed biophysical properties of voltage gated ion channels from the fruitfly Drosophila melanogaster are used to develop a minimal, conductance based neuron model. We investigate the impact of the densities of these channels on the excitability of the model neuron. Changing the channel densities reproduces different in situ observed firing patterns and induces a switch from integrator to resonator properties. Further, we analyze the preference to input frequency and how it depends on the channel densities and the resulting bifurcation type the system undergoes. An extension to a three dimensional model demonstrates that the inactivation kinetics of the sodium channels play an important role, allowing for firing patterns with a delayed first spike and subsequent high frequency firing as often observed in invertebrates, without altering the kinetics of the delayed rectifier current. PMID:26635592

  11. INFLUENCE OF EXPERIMENTAL CONDITIONS ON THE LIQUID SECONDARY ION MASS SPECTRA OF SULFONATED AZO DYES

    EPA Science Inventory

    Two monosulfonated and eight disulfonated azo dyes of varying relative molecular mass were examined by liquid secondary ion mass spectrometry (LSIMS). he effects of matrix, concentration, primary beam energy, and mode of operation were addressed in order to optimize sample ioniza...

  12. Influence of ion implantation on dielectric charging in capacitive RF MEMS switches

    NASA Astrophysics Data System (ADS)

    Li, Gang; Zhan, Linxian; San, Haisheng; Xu, Peng; Chen, Xuyuan

    2008-03-01

    Dielectric charging is one of the main problems leading to failure of capacitive RF MEMS switches. In this work phosphorus or boron ions were implanted into dielectric layer by ion implantation. After dielectric layer modification by ion implantation, we focus on investigation of the mechanisms of the charge accumulation and recombination after the sample electrically stressed with 80 V for 30 seconds. A Metal-Insulator-Semiconductor (MIS) capacitor structure is used for such an investigation. Silicon nitride films as the insulator in MIS structure were deposited by LPCVD process. The space charge accumulation in the silicon nitride film can be characterized by Capacitance-Voltage (C-V) measurement. Because of the ionization of the gas in the operating environment of the switch, ion injection by actuation voltage during the operation of the RF MEMS switch will play the role to enhance the charge accumulation in the dielectric layer. Our work offers a principle to understand the effect of the operating environment to the lifetime and reliability of the RF capacitive MEMS switches.

  13. Influence of defects and displacements in sapphire doped with Ag+ ions

    NASA Astrophysics Data System (ADS)

    Chen, Hua-jian; Wang, Yu-hua; Zhang, Xiao-jian; Zheng, Li-rong

    2015-12-01

    The Ag:Al2O3 composites are prepared by Ag+ ions implantation with the acceleration voltage of 35 kV. The formation of silver nanoparticle and the surface plasma resonance (SPR) effect are studied. The appearance of absorption bands demonstrates the formation of silver nanoparticles in Al2O3. Long-time sputtering due to the high fluency removes the surface layer, and the embedded Ag NPs appear on the surface though the majorities are in the deeper area. The fluorescence spectrum of Ag:Al2O3 evaluated by Gaussian fitting consists of three peaks: 365 nm, 403 nm and 471 nm. These bands should be attributed to defects produced by the matrix and embedded Ag+ ions. In addition, a strong peak at 693 nm is supposed to be R line for Al2O3 in the emission spectrum (VUV spectrum). The crystal structure and optical properties of ion implanted sapphire have been changed after ion implantation and it is analyzed by defects and displacements. Eventually, the SRIM program is used to simulate the growth of nanoparticles with four stages.

  14. Single discharge of the matrix source of negative hydrogen ions: Influence of the neutral particle dynamics

    SciTech Connect

    Paunska, Ts.; Todorov, D. Shivarova, A.; Tarnev, Kh.

    2015-04-08

    The study presents two-dimensional (2D) fluid-plasma-model description of a planar-coil inductively-driven discharge, considered as a single element of a matrix source of volume-produced negative hydrogen ions. Whereas the models developed up to now have been directed towards description of the charged particle behavior in the discharge, including that of the negative ions, this model stresses on the role of the neutral particle dynamics and of the surface processes in the formation of the discharge structure. The latter is discussed based on comparison of results obtained for discharges in a flowing gas and at a constant gas pressure as well as for different values of the coefficient of atom recombination on the walls. The conclusions are that the main plasma parameters – electron density and temperature and plasma potential – determining the gas discharge regime stay stable, regardless of changes in the redistribution of the densities of the neutral particles and of the positive ions. With regards to the volume production of the ions, which requires high density of (vibrationally excited) molecules, the impact on the degree of dissociation of the coefficient of atom recombination on the wall is discussed.

  15. Influence of ion bombardment induced patterning of exchange bias in pinned artificial ferrimagnets on the interlayer exchange coupling

    SciTech Connect

    Hoeink, V.; Schmalhorst, J.; Reiss, G.; Weis, T.; Lengemann, D.; Engel, D.; Ehresmann, A.

    2008-06-15

    Artificial ferrimagnets have many applications as, e.g., pinned reference electrodes in magnetic tunnel junctions. It is known that the application of ion bombardment (IB) induced patterning of the exchange bias coupling of a single layer reference electrode in magnetic tunnel junctions with He ions is possible. For applications as, e.g., special types of magnetic logic, a combination of the IB induced patterning of the exchange bias coupling and the implementation of an artificial ferrimagnet as reference electrode is desirable. Here, investigations for a pinned artificial ferrimagnet with a Ru interlayer, which is frequently used in magnetic tunnel junctions, are presented. It is shown that in this kind of samples the exchange bias can be increased or rotated by IB induced magnetic patterning with 10 keV He ions without a destruction of the antiferromagnetic interlayer exchange coupling. An IrMn/Py/Co/Cu/Co stack turned out to be more sensitive to the influence of IB than the Ru based artificial ferrimagnet.

  16. Influence of steering effects on strain detection in AlGaInN/GaN heterostructures by ion channelling

    NASA Astrophysics Data System (ADS)

    Redondo-Cubero, A.; Lorenz, K.; Franco, N.; Fernández-Garrido, S.; Gago, R.; Smulders, P. J. M.; Muñoz, E.; Calleja, E.; Alves, E.

    2009-03-01

    Ion steering effects in the interface of heterostructures can strongly influence the shape and position of angular channelling scans leading to considerable error in the determination of strain by ion channelling. As an example, this paper presents channelling measurements on a near-lattice-matched AlGaInN/GaN heterostructure which show no shift between the angular scans from the quaternary layer and the underlying GaN substrate although high resolution x-ray diffraction data confirm the presence of strain in the layer. Such 'anomalous' behaviour was studied by means of Monte Carlo simulations for nitride ternary and quaternary films in the whole composition range. The simulations show that the thickness, magnitude of the distortion of the strained lattice and energy of the probing beam are critical parameters controlling the impact of steering. Three composition/strain regions were established for a typical beam of 2 MeV alpha particles corresponding to different intensities of the steering potential and in which strain measurements by ion channelling are (a) correct, (b) possible but require corrections and (c) not possible due to steering effects.

  17. Effets des electrons secondaires sur l'ADN

    NASA Astrophysics Data System (ADS)

    Boudaiffa, Badia

    Les interactions des electrons de basse energie (EBE) representent un element important en sciences des radiations, particulierement, les sequences se produisant immediatement apres l'interaction de la radiation ionisante avec le milieu biologique. Il est bien connu que lorsque ces radiations deposent leur energie dans la cellule, elles produisent un grand nombre d'electrons secondaires (4 x 104/MeV), qui sont crees le long de la trace avec des energies cinetiques initiales bien inferieures a 20 eV. Cependant, il n'y a jamais eu de mesures directes demontrant l'interaction de ces electrons de tres basse energie avec l'ADN, du principalement aux difficultes experimentales imposees par la complexite du milieu biologique. Dans notre laboratoire, les dernieres annees ont ete consacrees a l'etude des phenomenes fondamentaux induits par impact des EBE sur differentes molecules simples (e.g., N2, CO, O2, H2O, NO, C2H 4, C6H6, C2H12) et quelques molecules complexes dans leur phase solide. D'autres travaux effectues recemment sur des bases de l'ADN et des oligonucleotides ont montre que les EBE produisent des bris moleculaires sur les biomolecules. Ces travaux nous ont permis d'elaborer des techniques pour mettre en evidence et comprendre les interactions fondamentales des EBE avec des molecules d'interet biologique, afin d'atteindre notre objectif majeur d'etudier l'effet direct de ces particules sur la molecule d'ADN. Les techniques de sciences des surfaces developpees et utilisees dans les etudes precitees peuvent etre etendues et combinees avec des methodes classiques de biologie pour etudier les dommages de l'ADN induits par l'impact des EBE. Nos experiences ont montre l'efficacite des electrons de 3--20 eV a induire des coupures simple et double brins dans l'ADN. Pour des energies inferieures a 15 eV, ces coupures sont induites par la localisation temporaire d'un electron sur une unite moleculaire de l'ADN, ce qui engendre la formation d'un ion negatif transitoire

  18. The Influence of C-Ions and X-rays on Human Umbilical Vein Endothelial Cells.

    PubMed

    Helm, Alexander; Lee, Ryonfa; Durante, Marco; Ritter, Sylvia

    2016-01-01

    Damage to the endothelium of blood vessels, which may occur during radiotherapy, is discussed as a potential precursor to the development of cardiovascular disease. We thus chose human umbilical vein endothelial cells as a model system to examine the effect of low- and high-linear energy transfer (LET) radiation. Cells were exposed to 250 kV X-rays or carbon ions (C-ions) with the energies of either 9.8 MeV/u (LET = 170 keV/μm) or 91 MeV/u (LET = 28 keV/μm). Subculture of cells was performed regularly up to 46 days (~22 population doublings) post-irradiation. Immediately after exposure, cells were seeded for the colony forming assay. Additionally, at regular intervals, mitochondrial membrane potential (MMP) (JC-1 staining) and cellular senescence (senescence-associated β-galactosidase staining) were assessed. Cytogenetic damage was investigated by the micronucleus assay and the high-resolution multiplex fluorescence in situ hybridization (mFISH) technique. Analysis of radiation-induced damage shortly after exposure showed that C-ions are more effective than X-rays with respect to cell inactivation or the induction of cytogenetic damage (micronucleus assay) as observed in other cell systems. For 9.8 and 91 MeV/u C-ions, relative biological effectiveness values of 2.4 and 1.5 were obtained for cell inactivation. At the subsequent time points, the number of micronucleated cells decreased to the control level. Analysis of chromosomal damage by mFISH technique revealed aberrations frequently involving chromosome 13 irrespective of dose or radiation quality. Disruption of the MMP was seen only a few days after exposure to X-rays or C-ions. Cellular senescence was not altered by radiation at any time point investigated. Altogether, our data indicate that shortly after exposure C-ions were more effective in damaging endothelial cells than X-rays. However, late damage to endothelial cells was not found for the applied conditions and endpoints. PMID

  19. The Influence of C-Ions and X-rays on Human Umbilical Vein Endothelial Cells

    PubMed Central

    Helm, Alexander; Lee, Ryonfa; Durante, Marco; Ritter, Sylvia

    2016-01-01

    Damage to the endothelium of blood vessels, which may occur during radiotherapy, is discussed as a potential precursor to the development of cardiovascular disease. We thus chose human umbilical vein endothelial cells as a model system to examine the effect of low- and high-linear energy transfer (LET) radiation. Cells were exposed to 250 kV X-rays or carbon ions (C-ions) with the energies of either 9.8 MeV/u (LET = 170 keV/μm) or 91 MeV/u (LET = 28 keV/μm). Subculture of cells was performed regularly up to 46 days (~22 population doublings) post-irradiation. Immediately after exposure, cells were seeded for the colony forming assay. Additionally, at regular intervals, mitochondrial membrane potential (MMP) (JC-1 staining) and cellular senescence (senescence-associated β-galactosidase staining) were assessed. Cytogenetic damage was investigated by the micronucleus assay and the high-resolution multiplex fluorescence in situ hybridization (mFISH) technique. Analysis of radiation-induced damage shortly after exposure showed that C-ions are more effective than X-rays with respect to cell inactivation or the induction of cytogenetic damage (micronucleus assay) as observed in other cell systems. For 9.8 and 91 MeV/u C-ions, relative biological effectiveness values of 2.4 and 1.5 were obtained for cell inactivation. At the subsequent time points, the number of micronucleated cells decreased to the control level. Analysis of chromosomal damage by mFISH technique revealed aberrations frequently involving chromosome 13 irrespective of dose or radiation quality. Disruption of the MMP was seen only a few days after exposure to X-rays or C-ions. Cellular senescence was not altered by radiation at any time point investigated. Altogether, our data indicate that shortly after exposure C-ions were more effective in damaging endothelial cells than X-rays. However, late damage to endothelial cells was not found for the applied conditions and endpoints. PMID

  20. The influence of ion gratings on rotational wavepacket dynamics inH2

    SciTech Connect

    Stavros, Vasilios G.; Leone, Stephen R.

    2007-11-24

    We generalize earlier work [V.G. Stavros, E. Harel, S.R.Leone, J. Chem. Phys. 122 (2005) 064301]by illustrating the plausiblerole ofion gratings in time-dependent degenerate four-wave mixing(TD-DFWM) experiments in H2. We postulate that at high laserintensities(1014 1015 W/cm2), H2+/H+ ions generate a static ion grating,it s signature manifested in the transformation from homodyne- toheterodyne-detection of the TD-DFWM signal, depending on laser intensity.The change in signal detection agrees with the calculated intensity forbarrier suppression ionization (BSI) in H2 and the reported onset ofsaturation for H2+ and H+, pointing towards the likely role of iongratings in intense laser field, FWM experiments.

  1. Influence of ions on genome packaging and ejection: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Ali, I.; Marenduzzo, D.

    2011-09-01

    We, theoretically, investigate the effect of ions on the packing and ejection dynamics of flexible and semiflexible polymers from spherical viral capsids. We find that when the polymer charge is less screened, or the Debye length increases (corresponding to a buffer with low concentration of a monovalent salt, such as Na+), the packing becomes more difficult and it may stop midway. Ejection, instead, proceeds more easily if the electrostatic screening is small. On the other hand, more screening (corresponding, for example, to the addition of divalent ions such as Mg2 +) results in easier packing and slower ejection. We interpret this as resulting from electrostatic forces among the various polymer sections, which can be tuned with the type of salt present in the solution. We also discuss how the DNA structure inside the capsid changes due to screened electrostatic interactions.

  2. The dynamics of a neoclassical tearing mode (NTM) influenced by energetic ions on EAST

    NASA Astrophysics Data System (ADS)

    Li, Erzhong; Igochine, V.; Xu, L.; Shi, T.; Zhao, H.; Liu, Y.; Ti, A.; White, R.; Zhang, J.; Zhu, Y.; Huang, J.; Shen, B.; Lin, S.; Qian, J.; Gong, X.; Hu, L.; Contributors, EAST

    2016-04-01

    In the 2014 year’s campaign of experimental advanced superconducting tokamak (EAST), a series of Magnetohydrodynamics (MHD) instabilities were observed as the launching of Neutral Beam Injection (NBI), the most interesting one of which is the neoclassical tearing mode (NTM). Evidence clearly shows that a kink mode present after a strong sawtooth-like (ST-like) crash leaves a perturbation near the location of the magnetic island, providing the initial seed. The interaction of energetic ions makes the magnetic island oscillate both in island width and in rotation frequency. Analysis indicates that the bulk plasma still dominates the dynamics of NTM, and the orbit excursion of energetic ions induces a polarization current and modifies the width and rotation frequency of the neoclassical magnetic island.

  3. Influence of land use on total suspended solid and dissolved ion concentrations: Baton Rouge, Louisiana area

    NASA Astrophysics Data System (ADS)

    Carlson, D.

    2015-03-01

    Past studies in the Baton Rouge, Louisiana area considered streamwater quality during storm events but ignored water quality during low flow periods. This study includes determination of streamwater quality during low flow time periods for none watersheds in East Baton Rouge Parish, Louisiana. These samples were collected during dry-low flow periods as indicated by water levels at USGS stream gauging sites for each stream. Chemical analysis for ions was completed using colorimeters and gravimetric analysis for total dissolved solids (TDS) and total suspended solids (TSS). Land use appears to impact concentrations of ions, TDS and TSS in a variety of ways during periods of low flow. The two most rural watersheds, which are mainly underdeveloped, have higher concentrations of Fe and Mn. By contrast the three most urban watersheds, that are mainly commercial, industrial or residential, have higher concentrations of Si, SO4 and TDS.

  4. The Influence of Trapped Ions and Non-equilibrium EDF on Dust Particle Charging

    SciTech Connect

    Sukhinin, G. I.; Fedoseev, A. V.; Antipov, S. N.; Petrov, O. F.; Fortov, V. E.

    2008-09-07

    Dust particles charging in a low-pressure glow discharge was investigated theoretically with the help of model for trapped and free ions coupled with the self-consistent solution of Poisson equation for electric potential. Non-equilibrium (non-Maxwellian) character of electron energy distribution function depending on gas pressure and electric field was also taken into account on the basis of the solution of kinetic Boltzmann equation. The results were compared with the experimental measurements of dust particle charge depending on gas pressure. It was shown that the calculated effective charge, i.e. the difference of the dust particle charge and trapped ion charge, is in a fairly good agreement with the experimental data.

  5. Influence of Fe ions on structural, optical and thermal properties of SnO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Ahmed, Ateeq; Tripathi, P.; Khan, Wasi; Dar, Abid Ahmed; Ali, Tinku

    2016-05-01

    In the present work, Fe doped SnO2 nanoparticles with the composition Sn1-xFexO2 (x = 0, 0.02, 0.04 and 0.06) have been successfully synthesized using sol-gel auto combustion technique. The samples are characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Ultraviolet (UV-Visible) absorption spectroscopy and thermal gravimetric analysis (TGA). The XRD study shows that all the samples have been found in tetragonal rutile structure without any extra phase and average crystallite size which lies in the range of 6-17 nm. The EDAX spectrum confirmed the doping of Fe ion into tin oxide nanomaterial. The optical band gap of doped SnO2 is found to decrease with increasing Fe ion concentration, which is due to the formation of donor energy levels in the actual band gap of SnO2.

  6. The influence of erythrocyte maturity on ion transport and membrane lipid composition in the rat.

    PubMed

    Vokurková, M; Rauchová, H; Dobešová, Z; Loukotová, J; Nováková, O; Kuneš, J; Zicha, J

    2016-01-01

    Significant relationships between ion transport and membrane lipid composition (cholesterol, total phospholipids and sphingomyelins) were found in erythrocytes of salt hypertensive Dahl rats. In these animals mean cellular hemoglobin content correlated negatively with Na(+)-K(+) pump activity and Na(+) leak but positively with Na(+)-K(+) cotransport activity. Immature erythrocytes exhibit lower mean cellular hemoglobin content (MCHC) than mature ones. The aim of the present study was to find a relationship between erythrocyte maturity, membrane lipid composition and ion transport activity in Wistar rats aged three months which were subjected to repeated hemorrhage (blood loss 2 ml/day for 6 days) to enrich circulating erythrocytes with immature forms. Immature and mature erythrocyte fractions in control and hemorrhaged rats were separated by repeated centrifugation. Hemorrhaged rats had increased number of reticulocytes but reduced hematocrit and MCHC compared to control rats. Immature erythrocytes of hemorrhaged rats differed from mature ones of control animals by elevated Na(+)-K(+) pump activity, reduced Na(+)-K(+) cotransport activity and increased Rb(+) leak. These ion transport changes in immature erythrocytes were accompanied by higher concentration of total phospholipids in their cell membranes. Membrane phospholipid content correlated positively with Na(+)-K(+) pump activity and cation leaks but negatively with Na(+)-K(+) cotransport activity. Moreover, they were also negatively related with MCHC which correlated negatively with Na(+)-K(+) pump activity and Rb(+) leak but positively with Na(+)-K(+) cotransport activity. Thus certain abnormalities of erythrocyte ion transport and membrane lipid composition detected in hypertensive animals might be caused by higher incidence of immature cells. PMID:26988297

  7. Influence of yttrium content on the location of rare earth ions in LYSO:Ce crystals

    SciTech Connect

    Ding, Dongzhou; Weng, Linhong; Yang, Jianhua; Ren, Guohao; Wu, Yuntao

    2014-01-15

    Single-crystal X-ray diffraction (SCD), X-ray fluorescence (XRF), inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray excited luminescence (XEL) measurements were performed to investigate structure details and segregation coefficients of (Lu{sub 1−x}Y{sub x}){sub 2}SiO{sub 5}:Ce (x=0 at%, 8.7 at%, 25.7 at%, 44.7 at%, 65.7 at%, 87.9 at% and 100 at%). Y{sup 3+} cations were found to have a preferential occupation for RE1 site (7-oxygen-coordinated) over RE2 site (6-oxygen-coordinated), which results in a greater increase of cell parameter c than that of a with increase in Y content due to LYSO's microstructure characteristics. Results presented here revealed that the less the difference in electronegativity and effective ionic radius between the two ions, the easier substitution of one ion by the other, and hence the higher segregation coefficients. Besides, the contribution of luminescence of Ce1 and Ce2 in the whole XEL was evaluated, and the location of Ce{sup 3+} ion was discussed. - Graphical abstract: Segregation coefficients of (Lu{sub 1−x}Y{sub x}){sub 2}SiO{sub 5}:Cce:italic> at RT/ce:italic>. Display Omitted.

  8. Influence of electrolyte ion-solvent interactions on the performances of supercapacitors porous carbon electrodes

    NASA Astrophysics Data System (ADS)

    Decaux, C.; Matei Ghimbeu, C.; Dahbi, M.; Anouti, M.; Lemordant, D.; Béguin, F.; Vix-Guterl, C.; Raymundo-Piñero, E.

    2014-10-01

    The development of advanced and safe electrochemical supercapacitors or hybrid supercapacitors combining a battery electrode material such as graphite and a porous carbon electrode implies the use of new electrolytes containing a tetra-alkylammonium or lithium salt dissolved preferentially in a safe and environmentally friendly solvent such as alkylcarbonates. In those systems, the carbon porosity of the activated carbon electrode controls the electrochemical behavior of the whole device. In this work, it is demonstrated that electrolytes containing highly polarizing ions such as Li+ dissolved in polar solvents such as alkylcarbonates do not completely loss their solvation shell at the opposite of what is observed for poorly solvated cations like TEABF4. As a consequence, the optimal carbon pore size for obtaining the largest energy density, while keeping a high power density, is wider when strongly solvated cations, like Li+ are used than for conventional organic electrolytes using acetonitrile as solvent and TEA+ as salt cations. TEA+ cations are easily desolvated and hence are able to penetrate in small pores matching the dimensions of bare ions. The dissimilarity of behavior of alkylcarbonates and acetonitrile based electrolytes highlights the importance of ion-solvent interactions when searching the optimal porous texture for the electrode material.

  9. Influence of phosphate ions on buffer capacity of soil humic acids

    NASA Astrophysics Data System (ADS)

    Boguta, P.; Sokołowska, Z.

    2012-02-01

    The object of this study was to determine change of natural buffer capacity of humic acids by strong buffering agents, which were phosphate ions. Studies were carried out on the humic acids extracted from peat soils. Additional information was obtained by determination of water holding capacity, density, ash and pH for peats and optical parameter Q4/6 for humic acids. Humic acid suspensions exhibited the highest buffer properties at low pH and reached maximum at pH ~ 4. Phosphates possessed buffer properties in the pH range from 4.5 to 8.0. The maximum of buffering was at pH~6.8 and increased proportionally with an increase in the concentration of phosphate ions. The study indicated that the presence of phosphate ions may strongly change natural buffer capacity of humic acids by shifting buffering maximum toward higher pH values. Significant correlations were found for the degree of the secondary transformation with both the buffer capacity and the titrant volume used during titration.

  10. Quantum chemical study of the photolysis mechanisms of sulfachloropyridazine and the influence of selected divalent metal ions.

    PubMed

    Shah, Shaheen; Zhang, Heming; Song, Xuedan; Hao, Ce

    2015-11-01

    Sulfonamides have been found in aquatic environments. Degradation of sulfachloropyridazine (SCP) mainly proceeds through direct and indirect photolysis in the aquatic environment. However, the mechanisms underlying the triplet photolysis of SCP and the influence of metal ions on the photolysis mechanism have not yet been fully explained. In this study, we elucidated the triplet photolysis mechanisms of SCP and the effects of three selected metal ions (Zn(2+), Ca(2+), and Cu(2+)) on the SCP photolysis mechanisms using quantum chemical calculation. Optimization of molecular structures and reaction pathways analysis of SCP were carried out at the B3LYP/6-31+G(d,p) level of theory. Two minimum energy pathways were investigated in the triplet photolysis of SCP. In Step 2 of Path-I, the photolysis product of SCP is a sulfur dioxide extrusion product, (4-(3-chloro-6-iminopyridazine-1(6H)-yl)aniline). The estimated activation energies of Step 2 and Step 3 of Path-I were much higher than in Path-II. Therefore, Path-II was found as the lowest energy pathway to obtain the SCP photoproducts, and Step 2 of Path-II was confirmed as the rate-determining step (RDS) in the photolysis mechanism of SCP. For the RDS of Path-II, computations with the three metal ions complexes (IM1-Cu(2+), IM1-Ca(2+), and IM1-Zn(2+)) show that the metal ions Cu(2+) and Ca(2+) promote triplet-sensitized photolysis of SCP by reducing the activation energy of RDS of Path-II, whereas Zn(2+) showed an inhibitory effect in photolysis of SCP by increasing the activation energy. PMID:26291757

  11. Reticulation des fibres lignocellulosiques

    NASA Astrophysics Data System (ADS)

    Landrevy, Christel

    Pour faire face à la crise économique la conception de papier à valeur ajoutée est développée par les industries papetières. Le but de se projet est l'amélioration des techniques actuelles de réticulation des fibres lignocellulosiques de la pâte à papier visant à produire un papier plus résistant. En effet, lors des réactions de réticulation traditionnelles, de nombreuses liaisons intra-fibres se forment ce qui affecte négativement l'amélioration anticipée des propriétés physiques du papier ou du matériau produit. Pour éviter la formation de ces liaisons intra-fibres, un greffage sur les fibres de groupements ne pouvant pas réagir entre eux est nécessaire. La réticulation des fibres par une réaction de « click chemistry » appelée cycloaddition de Huisgen entre un azide et un alcyne vrai, catalysée par du cuivre (CuAAC) a été l'une des solutions trouvée pour remédier à ce problème. De plus, une adaptation de cette réaction en milieux aqueux pourrait favoriser son utilisation en milieu industriel. L'étude que nous désirons entreprendre lors de ce projet vise à optimiser la réaction de CuAAC et les réactions intermédiaires (propargylation, tosylation et azidation) sur la pâte kraft, en milieu aqueux. Pour cela, les réactions ont été adaptées en milieu aqueux sur la cellulose microcristalline afin de vérifier sa faisabilité, puis transférée à la pâte kraft et l'influence de différents paramètres comme le temps de réaction ou la quantité de réactifs utilisée a été étudiée. Dans un second temps, une étude des différentes propriétés conférées au papier par les réactions a été réalisée à partir d'une série de tests papetiers optiques et physiques. Mots Clés Click chemistry, Huisgen, CuAAC, propargylation, tosylation, azidation, cellulose, pâte kraft, milieu aqueux, papier.

  12. The influence of the conditions of ion exchange in CuSO4:Na2SO4 melt on the optical properties of surface layers of silicate glass

    NASA Astrophysics Data System (ADS)

    Demichev, I. A.; Sidorov, A. I.; Nikonorov, N. V.

    2015-08-01

    The influence of the temperature and duration of ion exchange in BK7 silicate glass in CuSO4:Na2SO4 melt on the optical properties of the glass surface layers has been investigated. It is shown that ion exchange occurs from the melt according to the Cu2+ ↔ 2Na+ scheme. Cu2+ ions penetrate the sample to a depth of about 1 µm. Reduction of Cu2+ ions near the glass surface gives rise to the Cu+ ↔ Na+ ion exchange in the glass. Measurements of refractive index profiles in the glass sample subjected to ion exchange have revealed the formation of two waveguides in the sample: near the surface and at a depth of more than 3 µm; the second waveguide is formed by Cu+ ions. It is shown that relatively low temperatures and short durations of ion exchange lead to the formation of copper molecular clusters Cu n in glass. An increase of ion exchange temperature and duration leads to decomposition of molecular clusters with formation of Cu2+ ions.

  13. Influence of heavy ions on cell survival, cytogenetic damage and mitochondrial function of human endothelial cells

    NASA Astrophysics Data System (ADS)

    Ritter, Sylvia; Helm, Alexander; Lee, Ryonfa; Pollet, Dieter; Durante, Marco

    There is increasing evidence that there is an elevated risk of cardiovascular disease among atomic bomb survivors and radiotherapy patients, typically developing with a long latency. However, essentially no information is available on the potential cardiovascular risks associated with space radiation, in particular heavy ions. To address this issue, we have chosen human umbilical vein endothelial cells (HUVEC) as a model system. Cells at an early passage number were irradiated with 0.1 to 4 Gy of either 9.8 MeV/u C-ions (LET=170 keV/µm), 91 MeV/u C-ions (LET=29 keV/µm) or 250 kV X-rays. Cells were regularly subcultured up to 40 days (20 population doublings) post-irradiation. Immediately after exposure cell inactivation was deter-mined by the colony forming assay. Furthermore, at selected time-points cytogenetic damage (formation of micronuclei in binucleated cells) and the mitochondrial membrane potential ΨM (flow cytometric analysis following JC-1 staining) were assessed. Measurement of the directly induced radiation damage showed that 9.8 MeV/u and 91 MeV/u C-ions were more effective than X-rays (i.e. about 3 and 2 times, respectively) with respect to cell inactivation or the in-duction of cytogenetic damage. At the subsequent days in the irradiated cultures the number of cells with micronuclei declined to the control level (3-5Altogether our data indicate that under the applied radiation conditions the integrity of mitochondria which play a significant role in the regulation of cardiovascular cell function is not impaired. With respect to directly induced genetic damage C-ions are more effective than X-rays as observed in other cell systems. If the effectiveness of charged particles for the occurrence of late chromosomal damage in endothelial cells is higher than that of sparsely ionizing radiation needs further clarification. The data obtained up to now indicate that sophisticated cytogenetic techniques have to be applied in order to draw any firm

  14. The temperature and carbonate ion influence on Pleistocene high latitude planktonic foraminiferal carbon isotopic records

    NASA Astrophysics Data System (ADS)

    Charles, C.; Foreman, A. D.; Munson, J.; Slowey, N. C.; Hodell, D. A.

    2014-12-01

    Establishing a credible record of the carbon isotopic composition of high latitude surface ocean DIC over ice ages has been an enormous challenge, because the possible archives of this important variable in deep sea sediments all incorporate complex effects of the biomineralization process. For example, culture experiments (by Spero and colleagues) demonstrate a strong temperature and carbonate ion effect on the carbon isotopic composition of G. bulloides--the taxon of planktonic foraminifera that is most abundant in the majority of subpolar sediment sequences. Here we capitalize on the fortuitous observation of exceptionally strong covariation between the oxygen and carbon isotopic composition of G. bulloides in multiple sediment sequences from the Benguela upwelling region. The covariation is most clear during Marine Isotopic Stage 3 (an interval when the isotopic composition of the seawater was least variable) and undoubtedly results from the precipitation of tests under variable conditions of temperature and carbonate ion. The unusually clear isotopic relationship in planktonic foraminifera observed off Namibia constitutes a field calibration of the biomineralization effects observed in culture, and we apply it to previously published high latitude carbon isotopic records throughout the Southern Ocean. We find that many of the excursions toward lower planktonic foraminiferal δ13C that have been interpreted previously as the upwelling of nutrient rich water during deglaciations are better explained as increases in upper ocean temperature and carbonate ion. Conversely, the excursions toward high δ13C during ice age intervals that have been interpreted previously as increased export production (purportedly stimulated by dust) are also better explained by temperature and carbonate ion variability. After removal of the inferred temperature and carbonate ion signal from the planktonic foraminiferal time series, the residual is essentially (but not exactly) the same

  15. The influence of redistribution ions in subphase at the properties Langmuir monolayer: physical and theoretical experiments

    NASA Astrophysics Data System (ADS)

    Chumakov, A. S.; Ermakov, A. V.; Gorbachev, I. A.; Kossovich, E. L.; Kletsov, A. A.; Glukhovskoy, E. G.

    2016-04-01

    The formation of a monolayer and its structure depend on many factors. One of the least studied factors is the influence of the electric field. In this regard, the purpose of this study is to investigate the influence of the direction and magnitude of the electric field on the properties of monolayer, formed on the surface of water. The experiments have revealed: the electric field exerts a significant influence on the formation of monolayers, in particular, during liquid phase formation. The second part of the isotherm (corresponding liquid phase) were significantly stretched. We explain the liquid phase extension by the fact of the charge increasing (and change pH) of the surface region. To confirm this assumption also we made computer modelling of process monolayer formation.

  16. Factors influencing charge capacity of vanadium pentoxide thin films during lithium ion intercalation/deintercalation cycles

    SciTech Connect

    Alamarguy, D.; Castle, J. E.; Ibris, N.; Salvi, A. M.

    2007-11-15

    The intercalation of vanadium pentoxide by lithium ions leads to a change in optical properties, a process that is of value in thin-film electrochromic devices. In this study, films of V{sub 2}O{sub 5}, deposited on indium tin oxide (ITO) glass coupons by a sol-gel process, were challenged by increasing numbers of charge-discharge cycles ranging from 72 to 589 full cycles. The samples were characterized by x-ray photoelectron spectroscopy (XPS) and then examined in the deintercalated state by time-of-flight secondary ion mass spectroscopy (SIMS). XPS enabled measurement of the thickness and composition of the solid-electrolyte interface and provided evidence of the residual V{sup 4+} concentration within the top few nanometers of the surface. The SIMS profile gave direct information on the thickness of the films and on the thickness loss caused by rinsing the samples after the electrochemical exposure. Determination, by SIMS, of the concentration of lithium ions has enabled a correction to be made for the amount of inactive material within the electrochemically active region of the film. The SIMS depth profiles for lithium in the four samples are similar, with a marked buildup of Li at the interface with the ITO. This interphase zone had a thickness of {approx}27 nm and was electrochemically inactive, enabling a further correction to be made. Thus, by means of the XPS and the SIMS results the chemistry and thickness of the films could be fully characterized. The remaining inconsistency between capacity (between 35% and 100% of the anticipated charge) and number of cycles is ascribed to edge effects arising from the method used for production of the coupons.

  17. Influence of Multiple Genetic Polymorphisms on Genitourinary Morbidity After Carbon Ion Radiotherapy for Prostate Cancer

    SciTech Connect

    Suga, Tomo; Iwakawa, Mayumi; Tsuji, Hiroshi; Ishikawa, Hitoshi; Oda, Eisei; Noda, Shuhei; Otsuka, Yoshimi; Ishikawa, Atsuko; Ishikawa, Ken-Ichi; Shimazaki, Jun; Mizoe, Jun-Etsu; Tsujii, Hirohiko; Imai, Takashi

    2008-11-01

    Purpose: To investigate the genetic risk of late urinary morbidity after carbon ion radiotherapy in prostate cancer patients. Methods and Materials: A total of 197 prostate cancer patients who had undergone carbon ion radiotherapy were evaluated for urinary morbidity. The distribution of patients with dysuria was as follows: Grade 0, 165; Grade 1, 28; and Grade 2, 4 patients. The patients were divided (2:1) consecutively into the training and test sets and then categorized into control (Grade 0) and case (Grade 1 or greater) groups. First, 450 single nucleotide polymorphisms (SNPs) in 118 candidate genes were genotyped in the training set. The associations between the SNP genotypes and urinary morbidity were assessed using Fisher's exact test. Then, various combinations of the markers were tested for their ability to maximize the area under the receiver operating characteristics (AUC-ROC) curve analysis results. Finally, the test set was validated for the selected markers. Results: When the SNP markers in the SART1, ID3, EPDR1, PAH, and XRCC6 genes in the training set were subjected to AUC-ROC curve analysis, the AUC-ROC curve reached a maximum of 0.86. The AUC-ROC curve of these markers in the test set was 0.77. The SNPs in these five genes were defined as 'risk genotypes.' Approximately 90% of patients in the case group (Grade 1 or greater) had three or more risk genotypes. Conclusions: Our results have shown that patients with late urinary morbidity after carbon ion radiotherapy can be stratified according to the total number of risk genotypes they harbor.

  18. Influence of temperature on luminescence of terbium ions in LiNbO{sub 3}

    SciTech Connect

    Ryba-Romanowski, W.; Golab, S.; Dominiak-Dzik, G.; Palatnikov, M. N.; Sidorov, N. V.

    2001-06-04

    Single crystals of LiNbO{sub 3} doped with terbium were grown by the Czochralski method and their optical properties were examined. It has been found that, in contrast to isostructural LiTaO{sub 3}:Tb, the terbium ions in LiNbO{sub 3} exhibit intense luminescence at low temperatures only, up to about 150 K. At this temperature, a luminescence quenching mechanism with activation energy of 0.22 eV is switched on. As a consequence, the luminescence of LiNbO{sub 3}:Tb is reduced to a negligible level at room temperature. {copyright} 2001 American Institute of Physics.

  19. Influence of Inorganic Ions and Aggregation and Adsorption Behaviors of Human Adenovirus

    EPA Science Inventory

    In this study, influence of solution chemistries to the transport properties (aggregation and attachment behavior) of human adenovirus (HAdV) was investigated. Results showed isoelectric point (IEP) of HAdV in different salt conditions varied minimally, and it ranged from pH 3.5 ...

  20. Influence and analysis on ion barrier film to the noise factor of micro-channel plate

    NASA Astrophysics Data System (ADS)

    Zhu, Yu-feng; Zhang, Fan; Zhang, Ni; Nie, Jing; Li, Dan; Zhang, Tai-min; Wang, Shu-fei; Liu, Xiao-jian; Liu, Zhao-lu

    2015-03-01

    The noise factor, which is the main factor affecting the noise performance of image intensifier and can accurately reflect the noise characteristics of the micro-channel plate(MCP), is the ratio of the input signal to noise ratio (SNR) and the output SNR. According to definition of noise factor of micro channel plate, noise mechanism and test principle, noise factor of filmed MCP test system is established in order to study the technical way to reduce noise factor of MCP. Because the input surface of the MCP is covered with ion barrier film to block the feedback ions, which have a great impact on the noise factor of the MCP. Hence, noise factor of filmed MCP and un-filmed MCP is measured respectively, and noise factors with different materials and different filmed thickness are measured too. Relationships between noise factor and filmed thickness, noise factor and output SNR of image intensifier have been obtained. That is valuable to reduce the noise of filmed MCP.

  1. Influence of the plasma environment on atomic structure using an ion-sphere model

    DOE PAGESBeta

    Belkhiri, Madeny Jean; Fontes, Christopher John; Poirier, Michel

    2015-09-03

    Plasma environment effects on atomic structure are analyzed using various atomic structure codes. To monitor the effect of high free-electron density or low temperatures, Fermi-Dirac and Maxwell-Boltzmann statistics are compared. After a discussion of the implementation of the Fermi-Dirac approach within the ion-sphere model, several applications are considered. In order to check the consistency of the modifications brought here to extant codes, calculations have been performed using the Los Alamos Cowan Atomic Structure (cats) code in its Hartree-Fock or Hartree-Fock-Slater form and the parametric potential Flexible Atomic Code (fac). The ground-state energy shifts due to the plasma effects for themore » six most ionized aluminum ions have been calculated using the fac and cats codes and fairly agree. For the intercombination resonance line in Fe22+, the plasma effect within the uniform electron gas model results in a positive shift that agrees with the MCDF value of B. Saha et al.« less

  2. pH-Dependent Metal Ion Toxicity Influences the Antibacterial Activity of Two Natural Mineral Mixtures

    PubMed Central

    Cunningham, Tanya M.; Koehl, Jennifer L.; Summers, Jack S.; Haydel, Shelley E.

    2010-01-01

    Background Recent studies have demonstrated that several mineral products sold for medicinal purposes demonstrate antimicrobial activity, but little is known about the physicochemical properties involved in antibacterial activity. Methodology/Principal Findings Using in vitro mineral suspension testing, we have identified two natural mineral mixtures, arbitrarily designated BY07 and CB07, with antibacterial activity against a broad-spectrum of bacterial pathogens. Mineral-derived aqueous leachates also exhibited antibacterial activity, revealing that chemical, not physical, mineral characteristics were responsible for the observed activity. The chemical properties essential for bactericidal activity against Escherichia coli were probed by testing antibacterial activity in the presence of metal chelators, the hydroxyl radical scavenger, thiourea, and varying pH levels. Chelation of the BY07 minerals with EDTA or desferrioxamine eliminated or reduced BY07 toxicity, respectively, suggesting a role of an acid-soluble metal species, particularly Fe3+ or other sequestered metal cations, in mineral toxicity. This conclusion was supported by NMR relaxation data, which indicated that BY07 and CB07 leachates contained higher concentrations of chemically accessible metal ions than leachates from non-bactericidal mineral samples. Conclusions/Significance We conclude that the acidic environment of the hydrated minerals significantly contributes to antibacterial activity by increasing the availability and toxicity of metal ions. These findings provide impetus for further investigation of the physiological effects of mineral products and their applications in complementary antibacterial therapies. PMID:20209160

  3. Influence of the plasma environment on atomic structure using an ion-sphere model

    SciTech Connect

    Belkhiri, Madeny Jean; Fontes, Christopher John; Poirier, Michel

    2015-09-03

    Plasma environment effects on atomic structure are analyzed using various atomic structure codes. To monitor the effect of high free-electron density or low temperatures, Fermi-Dirac and Maxwell-Boltzmann statistics are compared. After a discussion of the implementation of the Fermi-Dirac approach within the ion-sphere model, several applications are considered. In order to check the consistency of the modifications brought here to extant codes, calculations have been performed using the Los Alamos Cowan Atomic Structure (cats) code in its Hartree-Fock or Hartree-Fock-Slater form and the parametric potential Flexible Atomic Code (fac). The ground-state energy shifts due to the plasma effects for the six most ionized aluminum ions have been calculated using the fac and cats codes and fairly agree. For the intercombination resonance line in Fe22+, the plasma effect within the uniform electron gas model results in a positive shift that agrees with the MCDF value of B. Saha et al.

  4. Formation of NDMA and halogenated DBPs by chloramination of tertiary amines: the influence of bromide ion.

    PubMed

    Le Roux, Julien; Gallard, Hervé; Croué, Jean-Philippe

    2012-02-01

    The formation of NDMA and other DBPs (including THMs, HANs, and HKs) has been investigated by chloramination of several tertiary amines in the absence and presence of bromide ion. NDMA formation from the most reactive tertiary amines (e.g., dimethylaminomethylfurfuryl alcohol or DMP30) was enhanced in the presence of bromide due to the formation of brominated oxidant species such as bromochloramine (NHBrCl) and the hypothetical UDMH-Br as an intermediate. The formation of NDMA by chloramination of less reactive model compounds was inhibited in the presence of bromide. This can be explained by competitive reactions leading to the production of brominated DBPs (i.e., THMs). In the presence of bromide, the formation of brominated THMs during chloramination can be attributed to the presence of small amounts of HOBr produced by the decomposition of chloramines and bromamines. The results are of particular interest to understand NDMA formation mechanisms, especially during chloramination of wastewaters impacted by anthropogenic tertiary amines and containing bromide ion. PMID:22214364

  5. Production of high resistivity water by electrodialysis. Influence of ion-exchange textiles as conducting spacers

    SciTech Connect

    Laktionov, E.; Dejean, E.; Sandeaux, J.; Sandeaux, R.; Gavach, C.; Pourcelly, G.

    1999-01-01

    Production of high resistivity water was investigated by electrodialysis (ED) using either inert or conducting spacers. Ion-exchange textiles were used as conducting spacers. Experiments were performed on a preindustrial scale with a pilot consisting of nine two-compartment cells, each membrane having an effective area of 176 cm{sup 2}. Three configurations of the ED stack were investigated for the dilution compartment: EDIT-(2) with a 2-mm thick ion-exchange textile, and ED-(2) or ED-(0.4), with a 0.4-mm thick inert spacer inserted between 2 or 0.4 mm thick dilution compartments, respectively. The textile induces a moderate increase in the pressure drop between the inlet and outlet of the stack. The performances of the different processes were compared under various experimental conditions of pH, nitrogen bubbling throughout the feed solution, flow rate, and current density. The results show that for an inlet conductivity of 10--15 {micro}S/cm, a flow rate of 2.2 {times} 10{sup {minus}5} m{sup 3}/s, and an applied voltage of 80 V, an outlet conductivity of 0.4 {micro}S/cm was obtained with the EDIT process, while no value lower than 5 {micro}S/cm was obtained with the ED process using both stacks.

  6. Influence of the plasma environment on atomic structure using an ion-sphere model

    NASA Astrophysics Data System (ADS)

    Belkhiri, Madeny; Fontes, Christopher J.; Poirier, Michel

    2015-09-01

    Plasma environment effects on atomic structure are analyzed using various atomic structure codes. To monitor the effect of high free-electron density or low temperatures, Fermi-Dirac and Maxwell-Boltzmann statistics are compared. After a discussion of the implementation of the Fermi-Dirac approach within the ion-sphere model, several applications are considered. In order to check the consistency of the modifications brought here to extant codes, calculations have been performed using the Los Alamos Cowan Atomic Structure (cats) code in its Hartree-Fock or Hartree-Fock-Slater form and the parametric potential Flexible Atomic Code (fac). The ground-state energy shifts due to the plasma effects for the six most ionized aluminum ions have been calculated using the fac and cats codes and fairly agree. For the intercombination resonance line in Fe22 +, the plasma effect within the uniform electron gas model results in a positive shift that agrees with the multiconfiguration Dirac-Fock value of B. Saha and S. Fritzsche [J. Phys. B 40, 259 (2007), 10.1088/0953-4075/40/2/002]. Last, the present model is compared to experimental data in titanium measured on the terawatt Astra facility and provides values for electron temperature and density in agreement with the maria code.

  7. Influence of anions on methylpyridinium ion adsorption on the mercury electrode in aqueous solutions

    SciTech Connect

    Gerovich, V.M.; Damaskin, B.B.; Ermolin, V.B.

    1987-02-01

    The adsorption behavior of aromatic and heterocyclic cations is known to be determined by image forces on one hand and by pi-electron interaction on the other. The first factor is effective at the negatively charged surface of the mercury electrode whereas the second factor is effective at the positively charged surface where the forces of pi-electron interaction are in opposition to the electrostatic repulsion forces of the cations. The authors of this paper study the adsorption of methylpyridinium as the aromatic cation in combination with persulfate, chlorine, bromine, and iodine as the anions. The potential range studied was limited on the anodic side by a potential of -0.1 eV, since the values of interfacial tension were poorly reproducible at more positive potentials, and on the cathodic side by a potential of -1.1 eV, since methylpyridinium is reduced at more negative potentials. It is found that the halide ions, owing to the possible formation of charge transfer complexes, have an even stronger effect on the adsorption behavior of organic cations than that observed previously for tetraalkylammonium ions.

  8. Influence of the isotope effect on the charge exchange in slow collisions of Li, Be, and C ions with H, D, and T

    SciTech Connect

    Tolstikhina, Inga Yu.; Shevelko, V. P.; Kato, Daiji

    2011-07-15

    The influence of the isotope effect (mass dependence) on the charge-exchange process in low-energy collisions of light ions with hydrogen isotopes (H, D, and T) is studied using the adiabatic theory of transitions in slow collisions developed by E. Solov'ev [Sov. Phys. Usp. 32, 228 (1989)]. Results of the numerical calculations are presented for the charge-exchange probabilities and cross sections of Li, Be, and C ions colliding with hydrogen isotopes and for the inverse reactions.

  9. Influence of the Ion Coordination Number on Cation Exchange Reactions with Copper Telluride Nanocrystals.

    PubMed

    Tu, Renyong; Xie, Yi; Bertoni, Giovanni; Lak, Aidin; Gaspari, Roberto; Rapallo, Arnaldo; Cavalli, Andrea; Trizio, Luca De; Manna, Liberato

    2016-06-01

    Cu2-xTe nanocubes were used as starting seeds to access metal telluride nanocrystals by cation exchanges at room temperature. The coordination number of the entering cations was found to play an important role in dictating the reaction pathways. The exchanges with tetrahedrally coordinated cations (i.e., with coordination number 4), such as Cd(2+) or Hg(2+), yielded monocrystalline CdTe or HgTe nanocrystals with Cu2-xTe/CdTe or Cu2-xTe/HgTe Janus-like heterostructures as intermediates. The formation of Janus-like architectures was attributed to the high diffusion rate of the relatively small tetrahedrally coordinated cations, which could rapidly diffuse in the Cu2-xTe NCs and nucleate the CdTe (or HgTe) phase in a preferred region of the host structure. Also, with both Cd(2+) and Hg(2+) ions the exchange led to wurtzite CdTe and HgTe phases rather than the more stable zinc-blende ones, indicating that the anion framework of the starting Cu2-xTe particles could be more easily deformed to match the anion framework of the metastable wurtzite structures. As hexagonal HgTe had never been reported to date, this represents another case of metastable new phases that can only be accessed by cation exchange. On the other hand, the exchanges involving octahedrally coordinated ions (i.e., with coordination number 6), such as Pb(2+) or Sn(2+), yielded rock-salt polycrystalline PbTe or SnTe nanocrystals with Cu2-xTe@PbTe or Cu2-xTe@SnTe core@shell architectures at the early stages of the exchange process. In this case, the octahedrally coordinated ions are probably too large to diffuse easily through the Cu2-xTe structure: their limited diffusion rate restricts their initial reaction to the surface of the nanocrystals, where cation exchange is initiated unselectively, leading to core@shell architectures. Interestingly, these heterostructures were found to be metastable as they evolved to stable Janus-like architectures if annealed at 200 °C under vacuum. PMID:27177274

  10. Influence of astigmatism on the fabrication of diffractive structures by use of focused ion-beam milling

    NASA Astrophysics Data System (ADS)

    Fu, Yongqi; Bryan, Ngoi Kok Ann

    2004-08-01

    Astigmatism exists in a focused-ion-beam (FIB) system and causes the shape of a beam spot to change from a normal circle to an ellipse. This variation influences the fabrication of diffractive structures by use of programmable controlled milling of a FIB. It is analyzed combined with the fabrication of blazed gratings and Fresnel diffractive lenses. Fabrication errors caused by a beam spot with astigmatism is discussed in detail for four cases of the long axis of an ellipse (a) in accordance with the X axis, (b) in accordance with the Y axis, (c) at 45° with the X axis, and (d) at -45° with the X axis. Finally, a method is given for correction of the astigmatism and how to determine the circularity of the beam spot qualitatively.

  11. Antidiarrhoeal activity of loperamide: studies of its influence on ion transport across rabbit ileal mucosa in vitro.

    PubMed Central

    Hughes, S; Higgs, N B; Turnberg, L A

    1982-01-01

    Loperamide is a well-established antidiarrhoeal agent with effects on gastrointestinal motility. We have now shown that the drug influences ion transport. In isolated rabbit ileal mucosa loperamide caused a dose-related fall in potential difference and short-circuit current and reduced the serosa to mucosa flux of chloride. The electrical effects were inhibited by naloxone (10(-6)M) suggesting that they were mediated by opiate receptors. Loperamide (10(-6)M) inhibited secretion provoked by heat stable and heat labile E. coli toxins and by prostaglandin E2. We conclude that loperamide is able to inhibit secretion mediated by cAMP or cGNP, and that this may be relevant to its antidiarrhoeal properties. PMID:6751949

  12. Influence of albumin and inorganic ions on electrochemical corrosion behavior of plasma electrolytic oxidation coated magnesium for surgical implants

    NASA Astrophysics Data System (ADS)

    Wan, Peng; Lin, Xiao; Tan, LiLi; Li, Lugee; Li, WeiRong; Yang, Ke

    2013-10-01

    Magnesium and its alloys are of great interest for biodegradable metallic devices. However, the degradation behavior and mechanisms of magnesium treated with coating in physiological environment in the presence of organic compound such as albumin have not been elucidated. In this study, the plasma electrolytic oxidation coated magnesium immersed in four different simulated body fluids: NaCl, PBS and with the addition of albumin to investigate the influence of protein and inorganic ions on degradation behavior by electrochemical methods. The results of electrochemical tests showed that aggressive corrosion took place in 0.9 wt.% NaCl solution; whereas albumin can act as an inhibitor, its adsorption impeded further dissolution of the coating. The mechanism was attributed to the synergistic effect of protein adsorption and precipitation of insoluble salts.

  13. Influence of other rare earth ions on the optical refrigeration efficiency in Yb:YLF crystals.

    PubMed

    Di Lieto, Alberto; Sottile, Alberto; Volpi, Azzurra; Zhang, Zhonghan; Seletskiy, Denis V; Tonelli, Mauro

    2014-11-17

    We investigated the effect of rare earth impurities on the cooling efficiency of Yb³⁺:LiYF₄ (Yb:YLF). The refrigeration performance of two single crystals, doped with 5%-at. Yb and with identical history but with different amount of contaminations, have been compared by measuring the cooling efficiency curves. Spectroscopic and elemental analyses of the samples have been carried out to identify the contaminants, to quantify their concentrations and to understand their effect on the cooling efficiencies. A model of energy transfer processes between Yb and other rare earth ions is suggested, identifying Erbium and Holmium as elements that produce a detrimental effect on the cooling performance. PMID:25402099

  14. Influence of rare earth ions on microstructural and optical properties of ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Riyajuddin, Sk.; Naseem, Swaleha; Khan, Wasi; Ahmad, Shabbir; Faizan, M.; Naqvi, A. H.

    2016-05-01

    Pure and 3% rare earth ions (Nd3+ & Gd3+) doped ZnO samples were synthesized by sol-gel method, followed by annealing at temperature 450°C for 2hr. The samples were characterized by XRD, FTIR and UV-visible spectroscopy. XRD result confirmed single phase nature of all samples with crystalline structure. The average crystallite size of the doped samples found to be decreases as caculated using Debye-Scherrer's formula. FTIR spectra indicate absorption band centered at 464 cm-1 which is attributed to Zn-O lattice vibration. It confirms the formaton of compounds. UV-visible spectroscopy was used to study the optical properties and band gap of the synthesised materials using Tauc's relation.

  15. In situ stress observation in oxide films and how tensile stress influences oxygen ion conduction

    PubMed Central

    Fluri, Aline; Pergolesi, Daniele; Roddatis, Vladimir; Wokaun, Alexander; Lippert, Thomas

    2016-01-01

    Many properties of materials can be changed by varying the interatomic distances in the crystal lattice by applying stress. Ideal model systems for investigations are heteroepitaxial thin films where lattice distortions can be induced by the crystallographic mismatch with the substrate. Here we describe an in situ simultaneous diagnostic of growth mode and stress during pulsed laser deposition of oxide thin films. The stress state and evolution up to the relaxation onset are monitored during the growth of oxygen ion conducting Ce0.85Sm0.15O2-δ thin films via optical wafer curvature measurements. Increasing tensile stress lowers the activation energy for charge transport and a thorough characterization of stress and morphology allows quantifying this effect using samples with the conductive properties of single crystals. The combined in situ application of optical deflectometry and electron diffraction provides an invaluable tool for strain engineering in Materials Science to fabricate novel devices with intriguing functionalities. PMID:26912416

  16. Influence of shell effects on the formation of light nuclei in collisions of heavy ions

    SciTech Connect

    Antonenko, N.V.; Dzholos, R.V. )

    1989-07-01

    Various approaches to calculation of the coefficients of the transport equation which describes the process of multinucleon transfers, are analyzed. It is shown that, without resorting to the averaging of matrix elements over many shell configurations, one can obtain expressions for transition probabilities that include the effects of nuclear shell structure. On this basis, the yield of light nuclei in reactions induced by heavy ions is studied in the framework of the degenerate-shell model. The calculations, which are carried out on the assumption that the wave functions of high-lying one-particle states of the system are not concentrated in one nucleus but are distributed over the two nuclei proportionally to their volumes, lead to an appreciable increase of the yield of light elements as compared to calculations in which one-particle states are assumed to belong to only one of the nuclei forming the double system.

  17. In situ stress observation in oxide films and how tensile stress influences oxygen ion conduction

    NASA Astrophysics Data System (ADS)

    Fluri, Aline; Pergolesi, Daniele; Roddatis, Vladimir; Wokaun, Alexander; Lippert, Thomas

    2016-02-01

    Many properties of materials can be changed by varying the interatomic distances in the crystal lattice by applying stress. Ideal model systems for investigations are heteroepitaxial thin films where lattice distortions can be induced by the crystallographic mismatch with the substrate. Here we describe an in situ simultaneous diagnostic of growth mode and stress during pulsed laser deposition of oxide thin films. The stress state and evolution up to the relaxation onset are monitored during the growth of oxygen ion conducting Ce0.85Sm0.15O2-δ thin films via optical wafer curvature measurements. Increasing tensile stress lowers the activation energy for charge transport and a thorough characterization of stress and morphology allows quantifying this effect using samples with the conductive properties of single crystals. The combined in situ application of optical deflectometry and electron diffraction provides an invaluable tool for strain engineering in Materials Science to fabricate novel devices with intriguing functionalities.

  18. In situ stress observation in oxide films and how tensile stress influences oxygen ion conduction.

    PubMed

    Fluri, Aline; Pergolesi, Daniele; Roddatis, Vladimir; Wokaun, Alexander; Lippert, Thomas

    2016-01-01

    Many properties of materials can be changed by varying the interatomic distances in the crystal lattice by applying stress. Ideal model systems for investigations are heteroepitaxial thin films where lattice distortions can be induced by the crystallographic mismatch with the substrate. Here we describe an in situ simultaneous diagnostic of growth mode and stress during pulsed laser deposition of oxide thin films. The stress state and evolution up to the relaxation onset are monitored during the growth of oxygen ion conducting Ce0.85Sm0.15O2-δ thin films via optical wafer curvature measurements. Increasing tensile stress lowers the activation energy for charge transport and a thorough characterization of stress and morphology allows quantifying this effect using samples with the conductive properties of single crystals. The combined in situ application of optical deflectometry and electron diffraction provides an invaluable tool for strain engineering in Materials Science to fabricate novel devices with intriguing functionalities. PMID:26912416

  19. Influence of organic ions on DNA damage induced by 1 eV to 60 keV electrons

    NASA Astrophysics Data System (ADS)

    Zheng, Yi; Sanche, Léon

    2010-10-01

    We report the results of a study on the influence of organic salts on the induction of single strand breaks (SSBs) and double strand breaks (DSBs) in DNA by electrons of 1 eV to 60 keV. Plasmid DNA films are prepared with two different concentrations of organic salts, by varying the amount of the TE buffer (Tris-HCl and EDTA) in the films with ratio of 1:1 and 6:1 Tris ions to DNA nucleotide. The films are bombarded with electrons of 1, 10, 100, and 60 000 eV under vacuum. The damage to the 3197 base-pair plasmid is analyzed ex vacuo by agarose gel electrophoresis. The highest yields are reached at 100 eV and the lowest ones at 60 keV. The ratios of SSB to DSB are surprisingly low at 10 eV (˜4.3) at both salt concentrations, and comparable to the ratios measured with 100 eV electrons. At all characteristic electron energies, the yields of SSB and DSB are found to be higher for the DNA having the lowest salt concentration. However, the organic salts are more efficient at protecting DNA against the damage induced by 1 and 10 eV electrons. DNA damage and protection by organic ions are discussed in terms of mechanisms operative at each electron energy. It is suggested that these ions create additional electric fields within the groove of DNA, which modify the resonance parameter of 1 and 10 eV electrons, namely, by reducing the electron capture cross-section of basic DNA units and the lifetime of corresponding transient anions. An interstrand electron transfer mechanism is proposed to explain the low ratios for the yields of SSB to those of DSB produced by 10 eV electrons.

  20. Influence of organic ions on DNA damage induced by 1 eV to 60 keV electrons

    SciTech Connect

    Zheng Yi; Sanche, Leon

    2010-10-21

    We report the results of a study on the influence of organic salts on the induction of single strand breaks (SSBs) and double strand breaks (DSBs) in DNA by electrons of 1 eV to 60 keV. Plasmid DNA films are prepared with two different concentrations of organic salts, by varying the amount of the TE buffer (Tris-HCl and EDTA) in the films with ratio of 1:1 and 6:1 Tris ions to DNA nucleotide. The films are bombarded with electrons of 1, 10, 100, and 60 000 eV under vacuum. The damage to the 3197 base-pair plasmid is analyzed ex vacuo by agarose gel electrophoresis. The highest yields are reached at 100 eV and the lowest ones at 60 keV. The ratios of SSB to DSB are surprisingly low at 10 eV ({approx}4.3) at both salt concentrations, and comparable to the ratios measured with 100 eV electrons. At all characteristic electron energies, the yields of SSB and DSB are found to be higher for the DNA having the lowest salt concentration. However, the organic salts are more efficient at protecting DNA against the damage induced by 1 and 10 eV electrons. DNA damage and protection by organic ions are discussed in terms of mechanisms operative at each electron energy. It is suggested that these ions create additional electric fields within the groove of DNA, which modify the resonance parameter of 1 and 10 eV electrons, namely, by reducing the electron capture cross-section of basic DNA units and the lifetime of corresponding transient anions. An interstrand electron transfer mechanism is proposed to explain the low ratios for the yields of SSB to those of DSB produced by 10 eV electrons.

  1. Intramembrane Aromatic Interactions Influence the Lipid Sensitivities of Pentameric Ligand-gated Ion Channels*

    PubMed Central

    Carswell, Casey L.; Sun, Jiayin; Baenziger, John E.

    2015-01-01

    Although the Torpedo nicotinic acetylcholine receptor (nAChR) reconstituted into phosphatidylcholine (PC) membranes lacking cholesterol and anionic lipids adopts a conformation where agonist binding is uncoupled from channel gating, the underlying mechanism remains to be defined. Here, we examine the mechanism behind lipid-dependent uncoupling by comparing the propensities of two prokaryotic homologs, Gloebacter and Erwinia ligand-gated ion channel (GLIC and ELIC, respectively), to adopt a similar uncoupled conformation. Membrane-reconstituted GLIC and ELIC both exhibit folded structures in the minimal PC membranes that stabilize an uncoupled nAChR. GLIC, with a large number of aromatic interactions at the interface between the outermost transmembrane α-helix, M4, and the adjacent transmembrane α-helices, M1 and M3, retains the ability to flux cations in this uncoupling PC membrane environment. In contrast, ELIC, with a level of aromatic interactions intermediate between that of the nAChR and GLIC, does not undergo agonist-induced channel gating, although it does not exhibit the expected biophysical characteristics of the uncoupled state. Engineering new aromatic interactions at the M4-M1/M3 interface to promote effective M4 interactions with M1/M3, however, increases the stability of the transmembrane domain to restore channel function. Our data provide direct evidence that M4 interactions with M1/M3 are modulated during lipid sensing. Aromatic residues strengthen M4 interactions with M1/M3 to reduce the sensitivities of pentameric ligand-gated ion channels to their surrounding membrane environment. PMID:25519904

  2. Vanadyl ions influence on spectroscopic and dielectric properties of glass network

    NASA Astrophysics Data System (ADS)

    Ramesh Babu, A.; Rajyasree, Ch.; Srinivasa Rao, P.; Vinaya Teja, P. M.; Krishna Rao, D.

    2011-11-01

    Melt quenching derived (in air) transparent glasses containing 30LiF sbnd 10SrO sbnd (60 - x)B 2O 3sbnd xV 2O 5, with 0 ⩽ x ⩽ 1.0 (mol%) were investigated for physical, spectroscopic measurements, viz., optical absorption, electron spin resonance (ESR) and FTIR along with dielectric properties (dielectric constant ɛ', loss tan δ, conductivity σac, etc.). The results were analyzed to correlate with each other in the light of local environment and oxidation states of vanadyl ion in the glass network. The observed blue shift in 3T 1g(F) → 3T 2g(F) and red shift in 2B 2g → 2E g transitions and decrease in Δ g∥/Δ g⊥ values up to V 8 indicates that the decrease in tetragonality of the vanadium site. The increase in area of optical absorption peak, ESR signal intensity and in the relative value of ac conductivity up to 0.8 mol% of V 2O 5 doped glasses is due to the predominant presence of V 4+ and V 3+ ions. Beyond this concentration, the redox ratio V 4+/V 5+ is found to decrease. By the gradual replacement of B 2O 3 by V 2O 5 up to 0.8 mol% the semi conducting nature of the glass network is found to increase due to increase of BO 3 structural units beyond this concentration insulating strength of glass matrix is increased.

  3. Influence of ion beam mixing on the growth of high temperature oxide superconducting thin film

    SciTech Connect

    Bordes, N.; Rollett, A.D.; Cohen, M.R.; Nastasi, M.

    1989-01-01

    The superconducting properties of high temperature superconductor thin films are dependent on the quality of the substrate used to grow these films. In order to maximize the lattice matching between the superconducting film and the substrate, we have used a YBa{sub 2}Cu{sub 3}O{sub 7} thin film deposited on {l angle}100{r angle} SrTiO{sub 3} as a template. The first film was prepared by coevaporation of Y, BaF{sub 2} and Cu on {l angle}100{r angle} SrTiO{sub 3}, followed by an anneal in wet'' oxygen at 850{degree}C. This film showed a sharp transition at about 90 K. A thicker layer of about 5000 A was then deposited on top of this first 2000 {angstrom} film, using the same procedure. After the post anneal at 850{degree}C, the transition took place at 80 K and no epitaxy of the second film was observed. Ion beam mixing at 400{degree}C, using 400 keV O ions was done at the interface of the two films (the second one being not annealed). After the post anneal, the film displayed an improved Tc at 90K. Moreover, epitaxy was shown to take place from the interface SrTiO{sub 3}-123 film towards the surface and was dependent of the dose. These results will be discussed from the data obtained from Rutherford backscattering spectroscopy (RBS) combined with channeling experiments, x-ray diffraction (XRD) and scanning electron microscopy (SEM) observations. 8 refs., 2 figs., 2 tabs.

  4. Revisiting heavy ion collisions under the influence of strong magnetic fields

    SciTech Connect

    Paoli, M. G. de; Menezes, D. P.

    2013-05-06

    The quark-gluon plasma (QGP) phase refers to matter where quarks and gluons are believed to be deconfined and it probably takes place at temperatures of the order of 150 to 170 MeV. In large colliders around the world (RHIC/BNL, ALICE/CERN, GSI, etc), physicists are trying to convert hadronic matter at these order of temperatures into QGP by looking at non-central heavy ion collisions. Possible experiments towards this search are Au-Au collisions at RHIC/BNL and Pb-Pb collisions at SPS/CERN, where the hadron abundances and particle ratios are used in order to determine the temperature and baryonic chemical potential of the possibly present hadronic matter-QGP phase transition. The magnetic fields involved in heavy-ion collisions, although time dependent and short-lived, can reach intensities higher than the ones considered in magnetars, around 1.7 Multiplication-Sign 10{sup 19} to 10{sup 20} Gauss. In fact, the densities related to the chemical potentials obtained within the relativistic models framework developed in previous works are very low (of the order of 10{sup -3} fm{sup -3}). At these densities the nuclear interactions are indeed very small and this fact made us consider the possibility of free Fermi and Boson gases under the unfluence of strong magnetic fields. We investigate the effects of magnetic fields of the order of 10{sup 18}, 10{sup 19} and 10{sup 20} G through a {chi}{sup 2} fit to some data sets of the STAR experiment. Our results shown that a field of the order of 10{sup 19} G can produce a much better fit to the experimental data than the calculations without magnetic fields.

  5. The corrosive influence of chloride ions preference adsorption on α-Al2O3 (0 0 0 1) surface

    NASA Astrophysics Data System (ADS)

    Zhang, Chuan-Hui; Liu, Min; Jin, Ying; Sun, Dong-Bai

    2015-08-01

    Conductor-like screening model (COSMO), Periodic DFT calculations have been performed on a Al2O3 surface to model the influence of preference adsorption and interaction of chloride ions at increasing monolayer coverage on undefective passive film on Aluminum in solution environment. The results evidence that the critical monolayer of Cl- is 3/7, which is redefined. With increasing Cl- adsorption, both the first and second Cl- move from Al(1) atop and bridge10 sites to O(5) sites, suggesting that the weaker interaction between Cl- and Al2O3 surface but stronger interactions between three ions make the electrons uniformly occupy on the energy levels of them. More calculations shows that the preference adsorption sites of Cl- are independent of the surface area of oxide, and the adsorption energy decrease in three steps, each adsorption energy step only relate to the adsorption site and the morphology. On undefective oxide film, low coverage Cl- adsorption would restrain surface breakdown to happen which is consistent with the experiment results.

  6. Layered NaxMnO₂+z in sodium ion batteries-influence of morphology on cycle performance.

    PubMed

    Bucher, Nicolas; Hartung, Steffen; Nagasubramanian, Arun; Cheah, Yan Ling; Hoster, Harry E; Madhavi, Srinivasan

    2014-06-11

    Due to its potential cost advantage, sodium ion batteries could become a commercial alternative to lithium ion batteries. One promising cathode material for this type of battery is layered sodium manganese oxide. In this investigation we report on the influence of morphology on cycle performance for the layered NaxMnO2+z. Hollow spheres of NaxMnO2+z with a diameter of ∼5 μm were compared to flake-like NaxMnO2+z. It was found that the electrochemical behavior of both materials as measured by cyclic voltammetry is comparable. However, the cycle stability of the spheres is significantly higher, with 94 mA h g(-1) discharge capacity after 100 cycles, as opposed to 73 mA h g(-1) for the flakes (50 mA g(-1)). The better stability can potentially be attributed to better accommodation of volume changes of the material due to its spherical morphology, better contact with the added conductive carbon, and higher electrode/electrolyte interface owing to better wetting of the active material with the electrolyte. PMID:24820186

  7. Factors Influencing the Electron Yield of Needle-Ring Pulsed Corona Discharge Electron Source for Negative Ion Mobility Spectrometer

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Li, Shengli; Li, Mingshu

    2013-12-01

    A simple negative ion mobility spectrometer (IMS) is designed and used to investigate the factors that influence the number and efficiency of electrons generated by the needle-ring pulsed corona discharge electron source. Simulation with Ansoft Maxwell 12 is carried out to analyze the electric field distribution within the IMS, and to offer the basis and foundation for analyzing the measurement results. The measurement results of the quantities of electrons show that when the drift electric field strength and the ring inner diameter rise, both the number of effective electrons and the effective electron rate are increased. When the discharge voltage becomes stronger, the number of effective electrons goes up while the effective electron rate goes down. In light of the simulation results, mechanisms underlying the effects of drift electric field strength, ring inner diameter, and discharge voltage on the effective electron number and effective electron rate are discussed. These will make great sense for designing negative ion mode IMS using the needle-ring pulsed corona discharge as the electron source.

  8. Influences of Probe’s Morphology for Metal Ion Detection Based on Light-Addressable Potentiometric Sensors

    PubMed Central

    Shao, Chen; Zhou, Shuang; Yin, Xuebo; Gu, Yajun; Jia, Yunfang

    2016-01-01

    The sensing mechanism of binding Hg2+ into thymine-thymine (T-T) mismatched base pairs was introduced into a light-addressable potentiometric sensor (LAPS) with anti-Hg2+ aptamer as the sensing units. Three kinds of T-rich single-strand DNA (ssDNA) chains with different spacer lengths, from 0 to 12 –CH2 groups, were designed to investigate surface charge and morphological effects on the LAPS’ output. First, by comparing the responding of LAPS modified with three kinds of ssDNA, it was found that the best performance for Hg2+ sensing was exhibited by the probe without –CH2 groups. The detection limit of Hg2+ ion was 1 ppt under the optimal condition. Second, the cooperative effects of surface charge and morphology on the output were observed by the controlled experiments. The two effects were the negative charge balanced by metal cations and the morphological changing caused by the formation of T-Hg2+-T structure. In conclusion, not only the influences of the aptamer probe’s morphology and surface charge was investigated on the platform of LAPS, but also sensing Hg2+ ions was achieved for the first time by the presented aptamer LAPS. PMID:27187412

  9. Influence of conductivity on the capacity retention of NiO anodes in Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Spinner, Neil S.; Palmieri, Alessandro; Beauregard, Nicole; Zhang, Lichun; Campanella, James; Mustain, William E.

    2015-02-01

    The roles of conductivity and structure in the reversibility, rate capability, capacity and capacity retention of nickel oxide anodes for lithium-ion batteries were investigated. Conductivity was controlled by the systematic addition of non-intercalating carbon. The NiO nanostructure was controlled through four different preparation procedures. Overall, the top-performing electrodes were made from tetrahedral-shaped particles with a broad particle size distribution that were derived from a simple direct calcination of nickel nitrate salt. Capacity values >700 mA h/g after 100 cycles at 1C were observed, and a rate capability >400 mA h/g at 5C was achieved for electrodes with 40% carbon added. The addition of carbon universally improved anode performance by influencing the charge transferability, as evidenced by SEI peak shifts and reduced resistances seen via EIS. Reversibility was greatly enhanced as the conductivity was improved through carbon addition, which enabled otherwise inactive anode particles to maintain activity after many cycles. This work suggests that improved conductivity, as opposed to the conventional opinion regarding nanostructure, is the key to creating high performance anodes for next generation lithium-ion batteries.

  10. Spatial and seasonal variation of salt ions under the influence of halophytes, in a coastal flat in eastern China

    NASA Astrophysics Data System (ADS)

    Wu, Yanyou; Liu, Rongcheng; Zhao, Yuguo; Li, Pingping; Liu, Congqiang

    2009-06-01

    The high salinity of coastal saline field is a key factor limiting the reclamation. Halophytes have been utilized in the reclamation of saline land. The study area is in Yancheng, China. An analysis of the concentrations of Rb, Cs, Sr, and Ba, the ratio of Rb/Cs, and Sr/Ba in soils in autumn shows that the soil of this study area has great homogeneity. Artemisia halodendron, Gossypium hirsutum, and Sesbania cannabina were selected as the reclamation plants in the present study. In order to know the spatial-temporal distribution of soil salinity, the influence of plant-specific vegetation, and the difference of desalination among these halophytes in coastal flat, the authors analyze the soil-layers and seasonal variation in salt ions. Sodium chloride was accumulated in 0-5 cm topsoil with no vegetation during the winter and spring. The effect of desalinization of halophytes is significant. Of the three plant species, Sesbania cannabina has the greatest desalinization. The difference of ions composition of soils covered with various plant species is significant. It can be concluded that halophytes have better amelioration of coastal soil salinity. Special attention should be paid to the selection of plant species and measures to plant and cultivate crops in the reclamation of saline land.

  11. Influence of temperature on the colloidal stability of the F-DPPC and DPPC liposomes induced by lanthanum ions.

    PubMed

    Toimil, Paula; Daviña, Rocío; Sabín, Juan; Prieto, Gerardo; Sarmiento, Félix

    2012-02-01

    The influence of La(3+) on the colloidal stability of liposomes made up by two zwitterionic phospholipids, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1-palmitoyl-2-[16-fluoropalmitoyl-phosphatidylcholine (F-DPPC), in aqueous media has been investigated by dynamic light scattering and electrophoretic mobility. The critical aggregation concentration (c.a.c.) of La(3+) for F-DPPC and DPPC liposomes were experimentally obtained, and the results were compared with theoretical predictions using the Derjaguin-Landau-Verwey-Overbeek theory. In order to evaluate the influence of the state of the bilayer on the stability of liposomes, all experiments were performed at temperatures below and above the chain-melting phase-transition temperature of lipids (transition temperature of lipids). Changes in the size of both types of liposomes and high values of polydispersity in the presence of La(3+) showed that these ions induce aggregation of liposomes at 25 °C and at 60 °C. At 25 °C, when the bilayer of F-DPPC liposomes is interdigited, DPPC liposomes are more resistant to aggregation than the liposomes formed with F-DPPC. However, this difference disappears at 60 °C, when both bilayers have the same conformation. The experimental results also indicate that the c.a.c. is higher at 60 °C than at 25 °C for both types of liposomes. In fact, it has been observed by dynamic light scattering measurements that aggregation of liposomes at 25 °C can be prevented by increasing the solution temperature for La(3+) concentrations near to the c.a.c. Moreover, the behavior of these liposomes in the presence of the ion was studied at temperatures above and below the transition temperature of the phospholipids. PMID:22041198

  12. Influence d'une substitution partielle du ciment par du laitier de hauts fourneaux sur la résistance des mortiers en milieu acide

    NASA Astrophysics Data System (ADS)

    Achoura, D.; Lanos, Ch.; Jauberthie, R.; Redjel, B.

    2004-11-01

    Le stockage de produits chimiques dans du béton présente souvent des problèmes de durabilité dus aux attaques chimiques. Inévitablement les concentrations élevées sont les plus dangereuses. Le but de notre étude est de déterminer les changements de phases qui apparaissent dans le béton lorsqu'on substitue une partie du ciment par du laitier de haut fourneaux. Les échantillons sont conservés dans des solutions acides différents anions (HCl, H{2}SO{4}, H{3}PO{4} et CH{3}COOH) et différentes concentrations (0,1; 0,25 et 0,5M). Les formations qui apparaissent sont déterminées par diffraction X et observées au MEB. Les solutions sulfatiques conduisent à une formation de gypse en surface et d'ettringite au contact de la matrice cimentaire. Avec l'acide acétique, il y a formation de calcium acétate hydrate sous forme spongieuse tandis que, avec l'acide phosphatique, la formation de calcium hydrogeno phosphate hydrate est très superficielle. Enfin, avec l'acide chlorhydrique, la surface du mortier est recouverte de chlorure de calcium dihydrate et d'hydroxyde de fer. Les résistances mécaniques sont plus ou moins affectées par la concentration mais aussi et surtout par la nature des acides avec dans l'ordre le plus agressif H{2}SO{4} puis HCl et CH{3}COOH enfin peu de modification pour H{3}PO{4}.

  13. Influence of optical thickness and hot electrons on Rydberg spectra of Ne-like and F-like copper ions.

    PubMed

    Fournier, K B; Faenov, A Ya; Pikuz, T A; Skobelev, I Yu; Belyaev, V S; Vinogradov, V I; Kyrilov, A S; Matafonov, A P; Bellucci, I; Martellucci, S; Petrocelli, G; Auguste, T; Hulin, S; Monot, P; D'Oliveira, P

    2003-01-01

    for each ion considered. We have studied both opacity effects and hot-electron influence on high-n transitions of highly charged Ne-, F-, and O-like ions. PMID:12636606

  14. Influence of inorganic ions and selected emerging contaminants on the degradation of Methylparaben: A sonochemical approach.

    PubMed

    Sasi, Subha; Rayaroth, Manoj P; Devadasan, Dineep; Aravind, Usha K; Aravindakumar, Charuvila T

    2015-12-30

    The study on the possible pathway of hydroxyl radicals mediated sonolytic degradation of paraben in water is reported. Methylparaben (MPB) which is the most utilized of paraben family is selected as a model emerging pollutant. The influence of common anions and some selected emerging contaminants that may coexist in typical water matrix on the degradation pattern is analyzed alongside. Among the anions, carbonate presents a negative influence which is attributed to the competition for OH radical. Some emerging contaminants also showed negative impact on degradation as was clear from HPLC data. The intermediates, analyzed by LC-Q-TOF-MS include hydroxylated and hydrolytic products. Three major steps (aromatic hydroxylation, hydroxylation at the ester chain and hydrolysis) are proposed to involve in the reaction of OH radical with MPB which ultimately leads to mineralization. The intensity of formation and decay of mono and dihydroxy products of MPB in the presence of additives have also been evaluated. COD analysis indicates a percentage reduction of 98% at 90 min of sonolysis and further increase in the degradation time resulted complete mineralization, which became evident from the mass spectrometric data. MTT assay revealed considerable decrease in the potential cytotoxicity. PMID:26184803

  15. [INFLUENCE OF OLEAMIDE OF WATER AND ION TRANSPORT IN THE OSMOREGULATORY ORGANS].

    PubMed

    Shakhmatova, E I; Bogolepova, A E; Dubina, M V; Natochin, Yu V

    2015-01-01

    Application of oleamide (final concentration of 10 μM) at the skin basal surface of the frog, Rana temporaria L., augmented the short-circuit current (SCC) from 59.8 ± 2.5 to 78.2 ± 1.4 μA/cm2. Oleamide added to the serous membrane of the frog urinary bladder at a final dose of 1 μM induced more than 30-fold increase of osmotic permeability. The addition of arginine-vasotocin on the background of oleamide action further increased SCC across the isolated frog skin and osmotic permeability of the frog urinary bladder. Intraperitoneal injection of oleamide at a dose of 0.1 mM/100 g BW to water-loaded non-anesthetized Wistar rats decreased diuresis by 22%, enhanced solute-free water reabsorption and urinary sodium excretion by 31% and 55% respectively, but did not affect the renal potassium excretion. The results obtained provide evidence of similarity of oleamide and neurohypophyseal hormones effects on water and ion transport in epithelial cells of osmoregulatory organs in vertebrates. PMID:26983280

  16. Influence of pH on yeast immobilization on polystyrene surfaces modified by energetic ion bombardment.

    PubMed

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

    2013-04-01

    Plasma immersion ion implantation (PIII) treatment is a novel method for immobilizing yeast on polymer surfaces by covalent linkage. This study of the immobilization of Saccharomyces cerevisiae in both rehydrated and cultured forms showed that the density of cell attachment on PIII treated polystyrene (PS) was strongly dependent on the pH of the incubation medium and was higher for rehydrated yeast. A study of the surface charge was undertaken to explain this result. A high density of cell attachment occurs in acidic conditions (pH 3-5) and a significantly reduced cell density occurs in neutral and alkaline buffers (pH 6-10) for both types of yeast. Force measurements using atomic force microscopy show that a negative charge is present on polystyrene after PIII treatment. The charge is close to zero at pH 3 to pH 5 and increasingly negative from pH 6 to pH 10. Both rehydrated yeast and cultured yeast have negative electrophoretic mobility in the pH range studied. The repulsive forces are weak in acidic buffers and stronger in neutral and alkaline buffers, in good agreement with the cell densities observed. Rehydrated yeast cells are found to be more hydrophobic than cultured yeasts in the same buffer. The higher hydrophobicity explains the higher attachment of rehydrated yeast compared to cultured yeast. PMID:23298600

  17. Influence of sulphate ion on the electrical conductivity of lithium -boro-phosphate glasses

    NASA Astrophysics Data System (ADS)

    Narayana Reddy, C.; Chakradhar, R. P. S.

    2009-07-01

    The effect of Li2SO4 on the electrical conductivity of Li2O- B2O3- P2O5 glass system prepared by melt quenching technique has been studied. Frequency and temperature dependent conductivity measurements have been carried out in the frequency range of 10 Hz to 10 MHz and a temperature range of 523 K-603 K respectively. Conductivity in these glasses is governed by the incorporation of lithium salt in the macromolecular structure. It exhibits Arrhenius behavior over the entire temperature range. Addition of Li2SO4 expands the glass network. Consequently the conductivity increases while activation energy decreases. Impedance spectra of these glasses show a single semicircle indicating one type of conduction. The nature of conductivity behavior observed can be explained using Almond-West type power law with a single exponent σ (ω) = σ (0) + A ωs. The power law exponent (s) decreases with temperature. Scaling behavior has also been carried out using the reduced plots of conductivity with frequency, which suggests the ion transport mechanism remains unaffected by temperature and composition.

  18. Influence of Surface Coating on Metal Ion Release: Evaluation in Patients With Metal Allergy.

    PubMed

    Thomas, Peter; Weik, Thomas; Roider, Gabriele; Summer, Burkhard; Thomsen, Marc

    2016-05-01

    Nickel, chromium, and cobalt in stainless steel and Cobalt-chrome-molybdenum (CoCrMo) alloys may induce allergy. The objectives of this study were to evaluate surface coating regarding ion release, patch test reactivity, and arthroplasty performance. Materials and methods included patch test in 31 patients with metal allergy and 30 patients with no allergy to stainless steel and CoCrMo disks that are uncoated or coated by titanium nitride/zirconium nitride (TiN/ZrN). Assessment include atomic absorption spectrometry of released nickel, cobalt, and chromium from the disks after exposure to distilled water, artificial sweat and culture medium. Results showed that both coatings reduced the nickel and chromium release from stainless steel and CoCrMo disks and mostly the cobalt release from the disks (maximally 11.755 µg/cm(2)/5 d to 1.624 by Ti-N and to 0.442 by ZrN). Six of the 31 patients with metal allergy reacted to uncoated disks, but none reacted to the coated disks. The current authors report on exemplary patients with metal allergy who had symptom relief by revision with surface-coated arthroplasty. The authors concluded that the surface coating may prevent cutaneous and peri-implant allergic reactions. [Orthopedics. 2016; 39(3):S24-S30.]. PMID:27219723

  19. Influence of dry mixing and distribution of conductive additives in cathodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Bauer, Werner; Nötzel, Dorit; Wenzel, Valentin; Nirschl, Hermann

    2015-08-01

    Conductive additives, like carbon black or graphite, are essential components of lithium ion batteries due to the limited electrical conductivity of most electrode materials. However, there is still a lack of knowledge about the optimized distribution of these materials within the electrode. A dry mixing process is used in order to prepare a conductive coating by depositing carbon black on the surface of Li(Ni1/3Mn1/3Co1/3)O2 (NMC) cathode particles. It is demonstrated that this - from a theoretically point of view - favorable distribution does not allow the preparation of working electrodes without taking into account the role of the binder. After adding an organic binder to the slurry, the polymer deposits on top of the carbon shell during drying and inhibits the conductive contact between the particles. This can be avoided by a fraction of distributed carbon particles which are associated with the binder phase providing conductive paths through the isolating organic material. It is shown that carbon black and graphite are principally fulfilling this task, but both materials are leading to varying processing behavior and electrode properties.

  20. Thermal stability of porcine pepsin influenced by Al(III) ion: DSC study

    NASA Astrophysics Data System (ADS)

    Pavelkić, V. M.; Beljanski, M. V.; Antić, K. M.; Babić, M. M.; Brdarić, T. P.; Gopčević, K. R.

    2011-12-01

    Differential scanning calorimetry (DCS) has been used to determine thermodynamic profile of pepsin and the in vitro effect of Al(III) ions. Thermograms of pepsin unfolding in the presence and absence of aluminum were used to determine the binding constant, K L, in the pepsin-aluminium model system. The thermodynamic parameters were derived from DSC profiles at different ligand concentrations (1, 5 and 10 mM). The temperatures of thermal transitions ( T m), calorimetric (Δ H cal) and van't Hoff enthalpy (Δ H VH), Gibbs free energy, Δ(Δ G), of Al(III) binding to pepsin, as well as an average number of ligands bound to the native protein, were obtained from DSC profiles too. Temperature-dependent changes in the protein structure were also monitored by native PAGE electrophoresis. Increasing the temperature causes the decrease in electrophoretic mobility. Increase in concentration of Al(III) decelerate the migration of pepsin samples on concentration dependent manner. Analysis showed that ligand binding increases thermal stability of protein.

  1. Influence of constraints on axial growth reduction of cylindrical Li-ion battery electrode particles

    NASA Astrophysics Data System (ADS)

    Chakraborty, Jeevanjyoti; Please, Colin P.; Goriely, Alain; Chapman, S. Jonathan

    2015-04-01

    Volumetric expansion of silicon anode particles in a lithium-ion battery during charging may lead to the generation of undesirable internal stresses. For a cylindrical particle such growth may also lead to failure by buckling if the expansion is constrained in the axial direction due to other particles or supporting structures. To mitigate this problem, the possibility of reducing axial growth is investigated theoretically by studying simple modifications of the solid cylinder geometry. First, an annular cylinder is considered with lithiation either from the inside or from the outside. In both cases, the reduction of axial growth is not found to be significant. Next, explicit physical constraints are studied by addition of a non-growing elasto-plastic material: first, an outer annular constraint on a solid silicon cylinder, and second a rod-like inner constraint for an annular silicon cylinder. In both cases, it is found that axial growth can be reduced if the yield stress of the constraining material is significantly higher than that of silicon and/or the thickness of the constraint is relatively high. Phase diagrams are presented for both the outer and the inner constraint cases to identify desirable operating zones. Finally, to interpret the phase diagrams and isolate the key physical principles two different simplified models are presented and are shown to recover important qualitative trends of the numerical simulation results.

  2. Influence of Oxygen Ion Implantation on the Damage and Annealing Kinetics of Iron-Implanted Sapphire

    SciTech Connect

    Hunn, J.D.; McHargue, C.J.

    1999-11-14

    The effects of implanted oxygen on the damage accumulation in sapphire which was previously implanted with iron was studied for (0001) sapphire implanted with iron and then with oxygen. The energies were chosen to give similar projected ranges. One series was implanted with a 1:l ratio (4x10{sup 16} ions/cm{sup 2} each) and another with a ratio of 2:3 (4x10{sup 16} fe{sup +}/cm{sup 2}; 6x10{sup 16} O{sup +}/cm{sup 2}). Retained damage, X, in the Al-sublattice, was compared to that produced by implantation of iron alone. The observed disorder was less for the dual implantations suggesting that implantation of oxygen enhanced dynamic recovery during implantation. Samples were annealed for one hour at 800 and 1200 C in an oxidizing and in a reducing atmosphere. No difference was found in the kinetics of recovery in the Al-sublattice between the two dual implant conditions. However, the rate of recovery was different for each from samples implanted with iron alone.

  3. Influence of laser focal position on X-ray and ion emission of copper plasma

    NASA Astrophysics Data System (ADS)

    Chaurasia, S.; Tripathi, S.; Ryc, L.; Dhareshwar, L. J.

    2011-05-01

    X-ray emission from copper plasma produced by a sub-nanosecond Nd:glass laser was studied as a function of distance of the target from the focus position. Optimization of soft (0.7-1.56 keV) and hard (3.2-5 keV) X-ray emissions as a function of the laser focal position was studied. In addition, a thallium acid phthalate (TAP) crystal spectrometer with spectral resolution of 30 mÅ was also developed to study variation in X-ray line emission in the spectral range of 1.291-1.610 keV (7.7-9.6 Å) as a function of laser focal position. It is observed that the maximum soft X-ray emission is on either sides of the focus, indicating a dependence on plasma volume, whereas hard X-ray emission shows a single peak close to the 'best focus' position. The line X-ray emission intensity with respect to laser focal position also shows a double hump structure as in the case of soft X-ray emission. This indicates that the line emission is also a function of plasma volume. Scaling of X-ray yield with laser intensity has also been determined. Ion emission was also studied as a function of focal position variation. It is observed to match well with the trend shown by X-ray emission.

  4. The influence of vacancy generation at the initial stage of ion implantation

    SciTech Connect

    Parfenova, Elena S.; Knyazeva, Anna G.

    2014-11-14

    The paper presents a coupled isothermal model at the initial stage of a solid surface treatment with particle beams. Mechanical stresses arising due to the interaction of particles with the surface affect the redistribution of the implanted impurity. Vacancies in the metal surface and their generation under stress are also taken into account. The kinetic law is formulated on the basis of thermodynamics of irreversible processes. The authors used numerical investigation methods. As a result, they have obtained the distributions of impurity concentration and deformations for various time moments. The authors also compare the concentration and deformation profiles with and without vacancies and study the influences of some model parameters. The effect of vacancy generation on the diffusion has been established to lead to an increase in the depth of penetration, as well as in the concentration of impurities.

  5. Influence of lactose on the diffusion of calcium ions at physiological temperature.

    PubMed

    Verissimo, Luis M P; Ribeiro, Vânia C M; Ribeiro, Ana C F; Melia Rodrigo, M; Esteso, Miguel A

    2014-11-15

    Mutual diffusion coefficients for calcium chloride (0.100 mol dm(-3)) in aqueous solutions containing lactose at various concentrations (from 0.005 to 0.200 mol dm(-3)) have been measured at 37°C (physiological temperature), by using a conductimetric cell coupled to an automatic system to follow the diffusion. This cell uses an open-ended capillary method based on the measurement of the electrical resistance of a solution placed inside the capillaries at recorded times. The analysis of the CaCl2 diffusion coefficient values obtained suggests the presence of some CaCl2/lactose aggregates in the media, which are influenced by the temperature. PMID:24912727

  6. Influence of magnetic field on the electric breakdown in penning ion source.

    PubMed

    Mahjour-Shafiei, M; Noori, H; Ranjbar, A H

    2011-11-01

    A cold-cathode penning-type ion source has been developed in our laboratory to study the electric breakdown in this type of sources. The breakdown voltage was measured as a function of axial magnetic field, in the range of 440-600 G, and anode length, in steps of 14, 20, and 24 mm. The measurement was performed with stainless steel cathodes in argon gas at pressure of 4 × 10(-2) mbar. Furthermore, a model was developed to explain the breakdown voltage data. In the construction of the model, the first Townsend coefficient was not directly used to avoid difficulties originating from the non-uniformity of the electric field. The empirical parameters of the model were obtained using the experimental data. The equation γ = c × (E(z)/N)(n), expressing the effective secondary emission coefficient in terms of reduced electric field, which was needed in the modeling process, was inspired from previous works. The parameters c and n were then calculated from the empirical parameters of the model. The n parameter turned out to be 0.59, which differs from the value reported by other authors merely by 1.6%. Three values, 0.010, 0.013, and 0.017 corresponding to the three anodes were obtained for the c parameter. These numbers are in good agreement with 0.01, which has been reported in the previous works. It was also found that the value of n has a decisive impact on the breakdown voltage curve in the high breakdown voltage region. PMID:22128971

  7. Influence of magnetic field on the electric breakdown in penning ion source

    NASA Astrophysics Data System (ADS)

    Mahjour-Shafiei, M.; Noori, H.; Ranjbar, A. H.

    2011-11-01

    A cold-cathode penning-type ion source has been developed in our laboratory to study the electric breakdown in this type of sources. The breakdown voltage was measured as a function of axial magnetic field, in the range of 440-600 G, and anode length, in steps of 14, 20, and 24 mm. The measurement was performed with stainless steel cathodes in argon gas at pressure of 4 × 10-2 mbar. Furthermore, a model was developed to explain the breakdown voltage data. In the construction of the model, the first Townsend coefficient was not directly used to avoid difficulties originating from the non-uniformity of the electric field. The empirical parameters of the model were obtained using the experimental data. The equation γ = c × (Ez/N)n, expressing the effective secondary emission coefficient in terms of reduced electric field, which was needed in the modeling process, was inspired from previous works. The parameters c and n were then calculated from the empirical parameters of the model. The n parameter turned out to be 0.59, which differs from the value reported by other authors merely by 1.6%. Three values, 0.010, 0.013, and 0.017 corresponding to the three anodes were obtained for the c parameter. These numbers are in good agreement with 0.01, which has been reported in the previous works. It was also found that the value of n has a decisive impact on the breakdown voltage curve in the high breakdown voltage region.

  8. Influence of the Ion-to-Atom Ratio on the Structure of CeO2 Buffer Layer by Ion Beam Assisted E-Beam Evaporation

    NASA Astrophysics Data System (ADS)

    Kim, Chang Su; Jo, Sung Jin; Kim, Woo Jin; Koo, Won Hoe; Baik, Hong Koo; Lee, Se Jong

    2005-09-01

    Using ion-beam assisted e-beam evaporation with the ion beam directed at 55° to the normal of the film plane, (200) oriented CeO2 films with biaxial texture were deposited on Hastelloy C276 substrates at room temperature. The crystalline quality and in-plane orientation of films was investigated by X-ray diffraction 2θ-scan and Φ-scan, atomic force microscopy (AFM). It was shown that the in-plane and out-of-plane textures of the CeO2 films were controlled by the deposition parameters. The orientation of the films was studied as a function of ion-to-atom ratio and film thickness. The ion-to-atom ratio was varied by independently adjusting the deposition rate and the ion current density. Under optimum condition, (200) textured CeO2 films have been successfully grown on Hastelloy C276.

  9. Technical Note: Influence of Compton currents on profile measurements in small-volume ion chambers

    SciTech Connect

    Tanny, Sean; Sperling, Nicholas; Parsai, E. Ishmael; Holmes, Shannon

    2015-10-15

    Purpose: This work is to evaluate the effects of Compton current generation in three small-volume ionization chambers on measured beam characteristics for electron fields. Methods: Beam scans were performed using Exradin A16, A26, and PTW 31014 microchambers. Scans with varying chamber components shielded were performed. Static point measurements, output factors, and cable only irradiations were performed to determine the contribution of Compton currents to various components of the chamber. Monte Carlo simulations were performed to evaluate why one microchamber showed a significant reduction in Compton current generation. Results: Beam profiles demonstrated significant distortion for two of the three chambers when scanned parallel to the chamber axis, produced by electron deposition within the wire. Measurements of ionization produced within the cable identified Compton current generation as the cause of these distortions. The size of the central collecting wire was found to have the greatest influence on the magnitude of Compton current generation. Conclusions: Microchambers can demonstrate significant (>5%) deviations from properties as measured with larger volume chambers (0.125 cm{sup 3} and above). These deviations can be substantially reduced by averaging measurements conducted at opposite polarities.

  10. Influence of Humic Acid Complexation with Metal Ions on Extracellular Electron Transfer Activity.

    PubMed

    Zhou, Shungui; Chen, Shanshan; Yuan, Yong; Lu, Qin

    2015-01-01

    Humic acids (HAs) can act as electron shuttles and mediate biogeochemical cycles, thereby influencing the transformation of nutrients and environmental pollutants. HAs commonly complex with metals in the environment, but few studies have focused on how these metals affect the roles of HAs in extracellular electron transfer (EET). In this study, HA-metal (HA-M) complexes (HA-Fe, HA-Cu, and HA-Al) were prepared and characterized. The electron shuttle capacities of HA-M complexes were experimentally evaluated through microbial Fe(III) reduction, biocurrent generation, and microbial azoreduction. The results show that the electron shuttle capacities of HAs were enhanced after complexation with Fe but were weakened when using Cu or Al. Density functional theory calculations were performed to explore the structural geometry of the HA-M complexes and revealed the best binding sites of the HAs to metals and the varied charge transfer rate constants (k). The EET activity of the HA-M complexes were in the order HA-Fe > HA-Cu > HA-Al. These findings have important implications for biogeochemical redox processes given the ubiquitous nature of both HAs and various metals in the environment. PMID:26593782