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[en] The subject is covered in chapters, entitled: introduction -the negative ion of hydrogen (H-); ground states of complex atomic negative ions - theoretical considerations; electron affinities of the elements; atomic negative ions - excited states - autodetechment; molecular negative ions - ground states and excited electronic states; modes of formation of negative ions - formation by radioactive processes - radiative attachment and polar photodissociation - formation by three-body collisions and by collisions of electrons with molecules -dissociative attachment and polar dissociation - formation by capture of bound electrons; detachment of electrons from negative ions - photodetachment, field detachment and detachment by electron impact; detachment, charge transfer and other reactions between negative ions and neutral systems at low and intermediate energies; detachment, charge transfer and other reactions involving negative ions - collisions at high impact energies; recombination of negative and positive ions - mutual neutralization; negative ions in electric discharges, planetary and stellar atmospheres, trace analysis and tandem accelerators. (U.K.)
[en] This research is focused on improving the efficiency of the anion exchange process for purifying plutonium. While initially focused on plutonium, the technology could also be applied to other ion-exchange processes. Work in FY17 focused on the improvement and optimization of porous foam columns that were initially developed in FY16. These foam columns were surface functionalized with poly(4-vinylpyridine) (PVP) to provide the Pu specific anion-exchange sites. Two different polymerization methods were explored for maximizing the surface functionalization with the PVP. The open-celled polymeric foams have large open pores and large surface areas available for sorption. The fluid passes through the large open pores of this material, allowing convection to be the dominant mechanism by which mass transport takes place. These materials generally have very low densities, open-celled structures with high cell interconnectivity, small cell sizes, uniform cell size distributions, and high structural integrity. These porous foam columns provide advantages over the typical porous resin beads by eliminating the slow diffusion through resin beads, making the anion-exchange sites easily accessible on the foam surfaces. The best performing samples exceeded the Pu capacity of the commercially available resin, and also offered the advantage of sharper elution profiles, resulting in a more concentrated product, with less loss of material to the dilute heads and tails cuts. An alternate approach to improving the efficiency of this process was also explored through the development of a microchannel array system for performing the anion exchange.
[en] Polyion complex bilayers made of dioctadecyldimethylammonium poly-(styrene sulphonate) were tested for their usefulness as anion-sensing membranes of ion-sensitive field effect transistors (ISFETs). Doping of the polyion complex with the corresponding quaternary ammonium chloride enhanced the sensitivity of the anion ISFET. Anion ISFETs based on the ammonium-doped polyion complexes showed a near-Nernstian response in the Cl- activity range 0.1-1x10-4 M. Annealing of bilayer membranes at a temperature higher than its crystal-to-liquid crystal transition temperature improved to some extent the selectivity for Cl- with respect to other anions. Doping of the polyion complex with the corresponding quaternary ammonium perchlorate also afforded ClO4--sensitive membranes for ISFETs. (author). 19 refs.; 6 figs.; 1 tab
[en] Highlights: • The proportionality of HE/O2.- reaction was first demonstrated. • An improved LC/MS-based method was developed for real-time detection of intracellular O2.-. • The LC/MS-based detection of 2-OH-E+ is of high sensitivity and selectivity. • The LC/MS-based assay for relative profiling of intracellular O2.- is applicable. - Abstract: Superoxide anion (O2.-), as the first generated reactive oxygen species (ROS), has been considered to be highly deleterious to cell functions. The measurement of intracellular O2.- level is of great importance to uncover its roles in a variety of oxidative damage diseases. Hydroethidium (HE) fluorescence-based method is dominating intracellular O2.- assay by monitoring the unique product 2-OH-E+ of HE/O2.- reaction. However, the avoid-less cross-interference of red fluorescence limited its ability to provide trustworthy information on intracellular O2.- formation. By the detection of 2-OH-E+, we herein developed and validated an improved LC/MS-based method for the measurement of intracellular O2.-. Firstly, we demonstrated the proportionality of HE/O2.- reaction. Secondly, ungerimine was used as internal standard to eliminate daily basis and matrix effect in the LC/MS-based detection of 2-OH-E+. Afterward, the total protein concentration was utilized for cell number normalization. Accordingly, an equation was further proposed to calculate the relative abundance (RA) of intracellular O2.-. Finally, the developed method has been successfully utilized to evaluate the inhibitory effects of natural compounds on O2.- generation, the result of which was validated by the HE-based fluorescent measurement. Compared with the fluorescent measurement, the LC/MS-based intracellular O2.- assay method is more sensitive, selective and accurate.
[en] Electron attachment to diatomic and polyatomic molecules, as well as to complexes, clusters, bulk particles, and surfaces is considered. The relevant theoretical concepts involving the formation of autodetachment states in negative ions are presented. Experimental data on electron attachment processes are analysed from a general theoretical viewpoint. (reviews of topical problems)
[en] The distribution coefficients (Kd) of radioiodine, radiotellurium and antimony using hydrochloric acid of various concentrations and the anion exchange resin (Dowex 21k, Dowex 1 x2 and Amberlyst 21b) were studied. A similar study at different concentrations of NaOH was also done. The results showed that the three species, i.e. radioiodine, radiotellurium and antimony are strongly retained on the Dowex 21k, Dowex 1 x2 and Amberlyst 21b at 7 M HCl. Radioiodine was re-extracted from Dowex 21k or Amberlyst 21b into 5mM TBAB with a separation yield of 95%.
[en] A modification of the currently operating Calutron, magnetron, and modified duoPIGatron negative ion source is proposed; the modification should improve gas efficiency by more than an order of magnitude in the Calutron, a factor of 5 in the magnetron, and a factor of 2 in the duoPIGatron. (orig.)