Recent advances in experimental solid state NMR methodology for half-integer spin quadrupolar nuclei

Smith, M. R.

doi:10.1016/s0079-6565(98)00028-4

Cited by 335 publications

(212 citation statements)

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“…All the spectra show a single broad peak that remains effectively constant as the SrO content increases. This shape is characteristic of sodium observed in a glass where there is a spread of quadrupolar interactions (Kohn et al 1998;Smith & Van Eck 1999). The multiple field data can be used to constrain things since under MAS there are effectively two residual interactions affecting the observed lineshape.…”

Section: Structural Characterizationmentioning

confidence: 86%

Structure and properties of strontium-doped phosphate-based glasses

Neel

Chrzanowski

Pickup

et al. 2008

J. R. Soc. Interface.

139

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Owing to similarity in both ionic size and polarity, strontium (Sr 2C ) is known to behave in a comparable way to calcium (Ca 2C ), and its role in bone metabolism has been well documented as both anti-resorptive and bone forming. In this study, novel quaternary strontium-doped phosphate-based glasses, containing 1, 3 and 5 mol% SrO, were synthesized and characterized.31 P magic angle spinning (MAS) nuclear magnetic resonance results showed that, as the Sr 2C content is increased in the glasses, there is a slight increase in disproportionation of Q 2 phosphorus environments into Q 1 and Q 3 environments. Moreover, shortening and strengthening of the phosphorus to bridging oxygen distance occurred as obtained from FTIR. The general broadening of the spectral features with Sr 2C content is most probably due to the increased variation of the phosphate-cation bonding interactions caused by the introduction of the third cation. This increased disorder may be the cause of the increased degradation of the Sr-containing glasses relative to the Sr-free glass. As confirmed from elemental analysis, all Sr-containing glasses showed higher Na 2 O than expected and this also could be accounted for by the higher degradation of these glasses compared with Sr-free glasses. Measurements of surface free energy (SFE) showed that incorporation of strontium had no effect on SFE, and samples had relatively higher fractional polarity, which is not expected to promote high cell activity. From viability studies, however, the incorporation of Sr 2C showed better cellular response than Sr 2C -free glasses, but still lower than the positive control. This unfavourable cellular response could be due to the high degradation nature of these glasses and not due to the presence of Sr 2C .

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Section: Structural Characterizationmentioning

confidence: 86%

Structure and properties of strontium-doped phosphate-based glasses

Neel

Chrzanowski

Pickup

et al. 2008

J. R. Soc. Interface.

139

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“…The presence of the quadrupolar interaction makes spectra more complex to interpret, but can provide additional information on the coordination environments associated with neighbouring network formers and modifiers [38,70]. The quadrupolar interaction introduces a magnetic field-dependent effect through the second-order perturbation [58,69]. Hence by recording spectra at multiple applied magnetic fields and either simulating spectra using computer programs such as Quadfit [71] or plotting the change in the centre of gravity position of the lineshape the interactions can be deduced [22,72,73].…”

Section: Magic Angle Spinning Nuclear Magnetic Resonancementioning

confidence: 99%

“…The number of reports of 17 O of phosphates is still limited, but has grown significantly in the last few years. This probably results from the relatively large coupling constants 17 O experiences in phosphates with c Q [58,69] of approximately 4 MHz in NBOs, compared with BOs, which have c Q ∼ 7.5 MHz [75,76]. Such large values only really become accessible with the availability of high fields and faster MAS rates.…”

Section: Magic Angle Spinning Nuclear Magnetic Resonancementioning

confidence: 99%

Titanium-containing bioactive phosphate glasses

Kiani

Lakhkar

Salih

et al. 2012

Phil. Trans. R. Soc. A.

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The use of biomaterials has revolutionized the biomedical field and has received substantial attention in the last two decades. Among the various types of biomaterials, phosphate glasses have generated great interest on account of their remarkable bioactivity and favourable physical properties for various biomedical applications relating to both hard and soft tissue regeneration. This review paper focuses mainly on the development of titanium-containing phosphate-based glasses and presents an overview of the structural and physical properties. The effect of titanium incorporation on the glassy network is to introduce favourable properties. The biocompatibility of these glasses is described along with recent developments in processing methodologies, and the potential of Ti-containing phosphate-based glasses as a bone substitute material is explored.

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“…Various radiofrequency (RF) pulse sequences have been suggested [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], including shaped pulses [21,22], optimization of MQ coherence transfers [23][24][25], factors limiting the resolution [26][27][28][29][30], spectral editing [31], correlation between satellite and central transitions [32], suppression of sidebands by variable-speed MAS [33], spectra simulation [34][35][36], quantification of spectra with numerical simulation [37], lineshape analysis [38][39][40], and disorder analysis [41]. This method has been applied to the characterization of: (i) meso-and microporous materials such as alumina [42], aluminophosphate [11,12,[43][44][45]...…”

Section: Introductionmentioning

confidence: 99%

Procedures for Labeling the High-Resolution Axis of Two-Dimensional MQ-MAS NMR Spectra of Half-Integer Quadrupole Spins

Millot

Man

2002

Solid State Nuclear Magnetic Resonance

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The increasing development and application of the multiple-quantum MAS NMR for halfinteger quadrupole spins has led to various RF pulse sequences for improving the excitation of multiple-quantum coherences and their conversion to single-quantum coherences. As a result, several conventions for labeling the F1 dimension of a 2D MQ-MAS spectrum appear in the literature. The corresponding relations for extracting the isotropic chemical shift, the quadrupole coupling constant, and the asymmetry parameter from experimental data are not always provided. We analyze these various conventions systematically and propose a new one, similar to that introduced by J.-P. Amoureux and C. Fernandez (2000, Solid State NMR 10, 339-343). These various conventions are illustrated with 27 Al (I = 5/2) nuclei in aluminum acetylacetonate Al(CH 3 COCHCOCH 3 ) 3 . Another experimental problem often met, the aliasing of peaks in the 2D spectrum, is analyzed and illustrated with 27 Al (I = 5/2) in NH 4 Y zeolite and 23 Na (I = 3/2) in sodium pyrophosphate Na 4 P 2 O 7 . © 2002 Elsevier Science (USA)

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Recent advances in experimental solid state NMR methodology for half-integer spin quadrupolar nuclei

Cited by 335 publications

References 1 publication

Structure and properties of strontium-doped phosphate-based glasses

Structure and properties of strontium-doped phosphate-based glasses

Titanium-containing bioactive phosphate glasses

Procedures for Labeling the High-Resolution Axis of Two-Dimensional MQ-MAS NMR Spectra of Half-Integer Quadrupole Spins

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