Chemical Durability Studies of Waste-Simulant Doped Borosilicate Glasses

2003 ◽  
Vol 807 ◽  
Author(s):  
Adam Duddridge ◽  
Moinul Islam ◽  
Diane Holland ◽  
Charlie R. Scales
Keyword(s):  
Test Procedure ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Borosilicate Glasses ◽  
Nmr Studies ◽  
Mixed Alkali ◽  
Trivalent Cations ◽  
High Level Nuclear Waste ◽  
Angle Spinning ◽  
High Level

ABSTRACTA mixed-alkali modified borosilicate base glass used in the vitrification of high-level nuclear waste (HLW) has been doped with a number of waste simulants to between 2 and 12 mol%. The simulants have been chosen to give two distinct series of glasses: one consisting of trivalent ions having the form M2O3(where M is La, Bi, Al or Fe) and the other consisting of divalent simulants of the form MO (where M is Pb, Zn or Ba). An international standard Soxhlet leach test procedure was performed on each glass to study the effect of prolonged, moderate-temperature, dynamic water corrosion. Results of these studies show that, except for BaO, as the amount of simulant is increased, the amount of Na and Li leached decreases showing them to become more chemically resistant. These corrosion tests have been correlated to ionic (D.C.) conductivity measurements, which show a decrease in the conductivity of the glass as the amount of waste simulant is increased, and 11B magic-angle spinning nuclear magnetic resonance (MAS-NMR) studies, which have shown that, as more waste-simulant is loaded into the glasses the rate of conversion of [BO4] to [BO3] units increases. All of the data from these studies reflect the different network forming abilities of the divalent and trivalent cations.

NMR Investigation of Cation Distribution in HLW Wasteform Glass

2008 ◽  
Vol 1107 ◽  
Author(s):  
Diane Holland ◽  
Ben G Parkinson ◽  
Moinul M Islam ◽  
Adam Duddridge ◽  
Jonathan M Roderick ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Aqueous Corrosion ◽  
Alkali Cations ◽  
Chemical Behaviour ◽  
High Level Nuclear Waste ◽  
Angle Spinning ◽  
High Level ◽  
Physical And Chemical

AbstractMagic-angle-spinning NMR has been used to establish the structural roles of various cations added to the borosilicate glass which is used for the vitrification of high-level nuclear waste (HLW). Representative surrogate oxides with nominal valencies of +1, +2 and +3 have been studied which span the range of oxides from modifier to intermediate and conditional glassformer. NMR has been carried out on those nuclei which are accessible and the species observed have been correlated with the physical and chemical behaviour. The controlling factor is the manner in which the alkali cations partition between the various network groups, changing the distribution of silicon Qn species and the boron N4 ratio. Identifiable superstructural units are also present in these glasses. The aqueous corrosion rate increases with Q3 content, as does the weight loss due to evaporation from the melt. The activation energy for DC conduction scales with N4. Values of N4 obtained for these glasses deviate significantly from those predicted by the currently accepted model (Dell and Bray) and are strongly affected by the modifier or intermediate nature of the surrogate oxide and also by its effect on the distribution of nonbridging oxygens between the silicate and borate polyhedra.

scholarly journals High-resolution magic angle spinning NMR studies for metabolic characterization of Arabidopsis thaliana mutants with enhanced growth characteristics

PLoS ONE ◽  
2018 ◽  
Vol 13 (12) ◽  
pp. e0209695 ◽  
Author(s):  
Dieuwertje Augustijn ◽  
Niels van Tol ◽  
Bert J. van der Zaal ◽  
Huub J. M. de Groot ◽  
A. Alia
Keyword(s):  
Arabidopsis Thaliana ◽  
High Resolution ◽  
Magic Angle Spinning ◽  
Growth Characteristics ◽  
Magic Angle ◽  
Nmr Studies ◽  
Angle Spinning

Characterization of metallurgical-grade aluminas and their precursors by 27Al NMR and XRD

2007 ◽  
Vol 85 (10) ◽  
pp. 889-897 ◽  
Author(s):  
Linus M Perander ◽  
Zoran D Zujovic ◽  
Tania Groutso ◽  
Margaret M Hyland ◽  
Mark E Smith ◽  
...  
Keyword(s):  
Solid State ◽  
High Field ◽  
Structural Complexity ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Nmr Studies ◽  
Transition Alumina ◽  
Angle Spinning ◽  
Alpha Alumina

The structure of metallurgical- or smelter-grade aluminas (MGAs) is complex and poorly understood. Ultra-high-field solid-state 27Al NMR results on industrial as well as on laboratory-prepared aluminas are discussed in relation to XRD results. It is demonstrated that high-field NMR can effectively be used to quantify the proportion of the thermodynamically stable alpha-alumina phase in these materials. The results demonstrate that 27Al NMR is a vital adjunct to XRD methods to quantify the transition alumina phases that invariably dominate the MGAs. The nature of the disorder in these materials, determined by 27Al NMR, is also compared with literature data, such as XANES and EXAFS studies, on typical laboratory-prepared materials. The utility of 27Al NMR studies to provide new insight into the structural complexity of metallurgical aluminas is shown.Key words: solid-state magic-angle-spinning NMR, metallurgical-grade alumina, transition alumina, gamma-alumina, coordination number.

Proton Magic Angle Spinning NMR Reveals New Features in Photodynamically Treated Bacteria

2003 ◽  
Vol 58 (5-6) ◽  
pp. 401-407 ◽  
Author(s):  
Yngve Johansen ◽  
Hege Christin Widerøe ◽  
Jostein Krane ◽  
Anders Johnsson ◽  
Anders Johnsson
Keyword(s):  
Blue Light ◽  
Glycine Betaine ◽  
Aminolevulinic Acid ◽  
Irradiation Time ◽  
Regulatory Volume Decrease ◽  
Magic Angle Spinning ◽  
Eukaryotic Cells ◽  
Magic Angle ◽  
Nmr Studies ◽  
Angle Spinning

Abstract The bacterium Propionibacterium acnes is light-sensitive due to porphyrin-induced photosensitization. The light sensitivity increases with incubation of 5-aminolevulinic acid, ALA. For the first time, 1H magic angle spinning NMR spectroscopy is used to describe the photoinduced changes in the bacterium after ALA incubation. Successful photosensitization was performed with light-emitting diodes in the blue and red regions (430 and 654 nm, respectively). The irradiation setup, suitable for irradiation of bacaterium suspensions in petri dishes is described. For NMR studies blue light diodes with about 90 μmol/m2s were chosen. After blue light irradiation, the endogenous glycine betaine, proline, glutamate and choline levels in P. acnes decreased with increasing irradiation time. For sublethal light doses (50% survival fraction), the endogenous glycine betaine level decreased 80% on average. The corresponding percentages for proline, choline and glutamate were about 40, 25 and 10, respectively. It is hypothesized that the irradiation, inducing porphyrin photosensitization amplified by ALA incubation, leads to elimination of the osmolyte glycine betaine and possibly also proline by so-called regulatory volume decrease (RVD) mechanisms. These mechanisms are known to be active in several prokaryotic and eukaryotic cells when exposed to hypotonic stress. They are also known to be present in several eukaryotic cells during photodynamic therapy (PDT) exposure leading to hypotonoc stress. The findings contribute to the knowledge of the inactivation mechanisms of P. acnes in photosensitization, and could therefore be of interest in the efforts to use PDT as treatment of the acne disease.

Metabolic Profiling of Lung Granuloma inMycobacterium tuberculosisInfected Guinea Pigs: Ex vivo1H Magic Angle Spinning NMR Studies

2011 ◽  
Vol 10 (9) ◽  
pp. 4186-4195 ◽  
Author(s):  
B. S. Somashekar ◽  
Anita G. Amin ◽  
Christopher D. Rithner ◽  
JoLynn Troudt ◽  
Randall Basaraba ◽  
...  
Keyword(s):  
Metabolic Profiling ◽  
Guinea Pigs ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Nmr Studies ◽  
Angle Spinning
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