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TL;DR: In this article, the effect of combined ionic substitutions on bioactive glass structure and properties was investigated. But the authors focused on the hot forming domain, i.e. the ability to hot process (sinter, draw fibres) without adverse crystallization.
Abstract: Borosilicate bioactive glasses are promising for bone tissue engineering. The objective was to assess the impact of magnesium and/or strontium, when substituted for calcium on the glasses' thermal and dissolution properties. Both Mg and Sr substitution appeared to enhance the hot forming domain, i.e. the ability to hot process (sinter, draw fibres) without adverse crystallization. Structural analysis indicated that substitution of MgO and/or SrO for CaO results in changes in the BO3/BO4 ratio as well as in the ratio between bridging and non-bridging oxygen atoms in the silicate structure. Additionally, a de-shielding effect was noticed when Ca, Mg and Sr are present together in the glass network, possibly owing to PO43− charge-balanced preferentially by Na+. The Mg and/or Sr substitution resulted in a lower ion release in simulated body fluid and delayed formation of hydroxyapatite. However, once this layer formed it consisted of a Mg/Sr-substituted apatite. This work highlights the effect of combined ionic substitutions on bioactive glass structure and properties.
23 citations
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TL;DR: For Al containing compounds with different symmetry types of Al environment (from fourfold to 12-fold coordinated Al) it is revealed that Al K-XANES spectra are well reproduced by the XAFS code, based on the method of Hartree-Fock MT-potential generation, considering the photoelectron single-, double-and triple-scattering processes on approximately linear two-and three-atom chains, originated at the absorbing Al atom as mentioned in this paper.
Abstract: For Al containing compounds with different symmetry types of Al environment (from fourfold to 12-fold coordinated Al) it is revealed that Al K-XANES spectra are well reproduced by the XAFS code, based on the method of Hartree-Fock MT-potential generation, considering the photoelectron single-, double- and triple-scattering processes on approximately linear two- and three-atom chains, originated at the absorbing Al atom. The empirical `selection rules' for choosing these chains are obtained and the origins of features in spectra are interpreted using the SELCOMP code. The proposed EXAFS-like approach for Al K-XANES description is applied also to explain the differences in Al K-XANES spectra, caused by the replacement of Fe atoms by Al atoms in goethite (-FeOOH).
23 citations
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TL;DR: In this paper, a flexible design of femtosecond polycrystalline Cr:ZnS/Se master oscillators in the Kerr-Lens-Mode-Locked regime is presented.
Abstract: This paper summarizes recent improvements of output characteristics of polycrystalline Cr:ZnS/Se master oscillators in Kerr-Lens-Mode-Locked regime. We developed a flexible design of femtosecond polycrystalline Cr:ZnS and Cr:ZnSe lasers and amplifiers in the spectral range 2–3 μm. We obtained few-optical-cycle pulses with multi-Watt average power in very broad range of repetition rates 0.08–1.2 GHz. We also report on efficient nonlinear frequency conversion directly in the polycrystalline gain elements of ultra-fast lasers and amplifiers. In this work we also report on recent progress in spinning ring gain element technology and report to the best of our knowledge the highest output power of 9.2 W Fe:ZnSe laser operating in CW regime at 4150nm.
23 citations
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TL;DR: In this paper, a simple crystal field model, combined with a correction of size effects, is shown to be adequate for rationalizing the partitioning behavior of diamond-anvil cells.
23 citations
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TL;DR: In this article, the authors report on the occurrence of ancient lavas enriched in incompatible elements whereas on-axis samples are typical normal mid-ocean ridge basalts, implying that enriched melts reached the seafloor at intervals of about 150-200 kyr.
Abstract: [1] Temporal fluctuations of magmatic processes during the last 800 kyr have been investigated for the slow spreading Central Indian Ridge. The fluctuations are recorded by variations in lava chemistry along a 40 km long profile across the ridge. The temporal relations of the basalts were accurately restored using magnetic microanomalies. We report on the occurrence of ancient lavas enriched in incompatible elements whereas on-axis samples are typical normal mid-ocean ridge basalts. The enriched lavas are symmetrically distributed on either side of the ridge, implying that enriched melts reached the seafloor at intervals of about 150–200 kyr. This periodicity is viewed as a characteristic time scale in the aggregation processes of the melts produced from a heterogeneous mantle source. Geochemical variations of zero-age mid-ocean ridge basalts may primarily reflect such periodic processes rather than the spatial distribution of mantle heterogeneities.
23 citations
Authors
Showing all 903 results
Name | H-index | Papers | Citations |
---|---|---|---|
Claude J. Allègre | 106 | 327 | 35092 |
Paul Tapponnier | 99 | 294 | 42855 |
Francesco Mauri | 85 | 352 | 69332 |
Barbara Romanowicz | 67 | 284 | 14950 |
Geoffrey C. P. King | 64 | 157 | 17177 |
Yi-Gang Xu | 64 | 271 | 14292 |
Jérôme Gaillardet | 63 | 199 | 14878 |
François Guyot | 61 | 292 | 12444 |
Georges Calas | 60 | 266 | 10901 |
Ari P. Seitsonen | 59 | 212 | 45684 |
Michele Lazzeri | 58 | 140 | 57079 |
Bernard Bourdon | 58 | 118 | 9962 |
Gianreto Manatschal | 56 | 200 | 10063 |
Nikolai M. Shapiro | 56 | 154 | 15508 |
Guillaume Morin | 55 | 156 | 7218 |