Structural and luminescence studies on barium sodium borosilicate glasses containing uranium oxides

Barium sodium borosilicate glasses containing different amounts of uranium oxides were prepared by conventional melt quench method and investigated for their structural aspects by <SUP>29</SUP>Si and <SUP>11</SUP>B MAS NMR technique combined with steady-state luminescence and lifetime measurements. Based on MAS NMR studies, it is confirmed that uranium ions act as network modifier up to 15 wt% and beyond which a separate uranium containing phase is formed. From the luminescence studies, it is inferred that uranyl species is in a highly distorted environment. For more than 15 wt% uranium oxide incorporation, weaker U–O–U linkages are formed at the expense stronger U–O–Si/B linkages, as suggested by the excited state lifetime value of the uranyl species as well as red shift in emission peak maximum. For glass samples containing more than 25 wt% uranium oxides, crystalline barium uranium silicate gets phase separated from glass matrix as confirmed by XRD studies

Corrosion of borosilicate glasses subjected to aggressive test conditions: structural investigations

Sodium borosilicate (NBS) and barium sodium borosilicate (BBS) glasses, used for immobilization of high-level nuclear waste with compositions (SiO2)0.477(B2O3)0.239(Na2O)0.170(TiO2)0.023(CaO)0.068(Al2O3)0.023 and (SiO2)0.482(B2O3)0.244(Na2O)0.220(BaO)0.054 were subjected leaching experiments under hydrothermal conditions in an autoclave at 200°C for different time durations. Morphological and structural transformations associated with leaching, have been monitored with techniques like XRD, SEM, solid-state nuclear magnetic resonance. XRD and SEM along with NMR studies have confirmed that, upon leaching, formation of an aluminosilicate phase, Zeolite-P (Na6Al6Si10O32·12H2O), occurs with NBS glass. BBS glass upon subjecting to the same conditions leads to formation of multiple amorphous phases having Q4 (silica rich phase) and Q3 structural units of Silicon along with structurally modified residual glass. Upon leaching BO3 structural units preferentially get released from BBS glass. Comparison of results with international simple glass confirmed that, for the latter, mass loss rates are one order of magnitude lower

Role of sulfate in structural modifications of sodium barium borosilicate glasses developed for nuclear waste immobilization

A sodium barium borosilicate glass matrix with a higher solubility of sulfate has been developed recently at Bhabha Atomic Research Centre for vitrification of sulfate bearing high-level nuclear waste. We report here the studies carried out to understand the influence of sulfate ion on the three-dimensional borosilicate network. Experiments were carried out with sodium barium borosilicate base glass samples loaded with varying amounts of SO<SUB>4</SUB><SUP>2-</SUP> (0–5 mol%). Phase separation studies on the samples revealed that as much as 3 mol% of SO<SUB>4</SUB><SUP>2-</SUP> can be loaded within the base glass without any phase separation, however, beyond this limit BaSO<SUB>4</SUB> (barite) crystallizes within the matrix. Thermal analyses of the samples indicated a shift in glass transition temperature from 534° (0 mol% SO<SUB>4</SUB><SUP>2-</SUP>) to 495°C (3 mol% SO<SUB>4</SUB><SUP>2-</SUP>) and it remained more or less unaltered afterwards even with high SO<SUB>4</SUB><SUP>2-</SUP> loading. A similar observation of structure stabilization was obtained from <SUP>29</SUP>Si MAS–NMR studies also, which showed that with 2 mol% of SO<SUB>4</SUB><SUP>2-</SUP> loading, the Q<SUP>2</SUP>:Q<SUP>3</SUP> ratio changed from 59:41 (for samples with 0 mol% SO<SUB>4</SUB><SUP>2-</SUP> loading) to 62:38 and it remained almost the same afterwards even with higher SO<SUB>4</SUB><SUP>2-</SUP> loading. 11B MAS NMR patterns of the glass samples, however, remained unchanged with SO<SUB>4</SUB><SUP>2-</SUP> loading ([BO<SUB>4</SUB>]:[BO<SUB>3</SUB>]=38:62). Based on <SUP>29</SUP>Si and 11B MAS NMR studies, the authors propose two different ways of interaction of SO<SUB>4</SUB><SUP>2-</SUP> ions with the borosilicate network: (i) the network modifying action of SO<SUB>4</SUB><SUP>2-</SUP> ions with -Si–O–Si- linkages, at low SO<SUB>4</SUB><SUP>2-</SUP> ion concentration (&#60;2 mol%) and (ii) the preferential interaction of SO<SUB>4</SUB><SUP>2-</SUP> with the Ba<SUP>2+</SUP> ions at high SO<SUB>4</SUB><SUP>2-</SUP> concentration (>2 mol%)

Expert eValuation of Efficacy and Rationality of Vildagliptin “EVER-Vilda”: An Indian Perspective

Vildagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor is effective in reducing HbA1c levels in patients with type 2 diabetes (T2DM) when administered as monotherapy, dual or triple combination therapy. In India, Vildagliptin is commonly prescribed in T2DM patients because it reduces mean amplitude of glycemic excursion (MAGE), has lower risk of hypoglycemia and is weight neutral. Early combination therapy with vildagliptin and metformin is effective and well-tolerated in patients with T2DM, regardless of age or ethnicity. In view of already existing data on vildagliptin and the latest emerging clinical evidence, a group of endocrinologists, diabetologists and cardiologists convened for an expert group meeting to discuss the role and various combinations of vildagliptin in T2DM management. This practical document aims to guide Physicians and Specialists regarding the different available strengths and formulations of vildagliptin for the initiation and intensification of T2DM therapy

Abstracts of National Conference on Research and Developments in Material Processing, Modelling and Characterization 2020

This book presents the abstracts of the papers presented to the Online National Conference on Research and Developments in Material Processing, Modelling and Characterization 2020 (RDMPMC-2020) held on 26th and 27th August 2020 organized by the Department of Metallurgical and Materials Science in Association with the Department of Production and Industrial Engineering, National Institute of Technology Jamshedpur, Jharkhand, India. Conference Title: National Conference on Research and Developments in Material Processing, Modelling and Characterization 2020Conference Acronym: RDMPMC-2020Conference Date: 26–27 August 2020Conference Location: Online (Virtual Mode)Conference Organizer: Department of Metallurgical and Materials Engineering, National Institute of Technology JamshedpurCo-organizer: Department of Production and Industrial Engineering, National Institute of Technology Jamshedpur, Jharkhand, IndiaConference Sponsor: TEQIP-