We have discovered nine presolar silicate grains from the carbonaceous chondrite Acfer 094. Their anomalous oxygen isotopic compositions indicate formation in the atmospheres of evolved stars. Two grains are identified as pyroxene, two as olivine, one as a glass with embedded metal and sulfides (GEMS), and one as an Al-rich silicate. One grain is enriched in 26Mg, which is attributed to the rad...

Transmission of intense femtosecond 825 nm pulses progressively produces a waveguide at the entrance of a heavily Ge-doped silicate fiber. The waveguide behaves as a multimillimeter long-fiber bandpass filter that scatters away light with wavelengths shorter or longer than 850 nm. This phenomenon has been correlated with the ~800 nm photosensitivity producing type I-IR fiber Bragg gratings in s...

A correlation between the elastic modulus and photoelastic constant (PEC) was studied in binary Sn2+- Bi3+-containing silicate glass. The Young’s shear moduli decrease with increase refractive index, whereas they PEC. former is directly related to strain-optic coefficient, latter inversely elasto-optic coefficient. working hypothesis for obtaining highly very small glass proposed based on short...

After several decades of study, the nature glass state and transition remains controversial. This work describes a newly proposed two-stage model for silicate transition. The recognizes that there is cooling rate independent critical temperature Tc, separating two regions. coherent structures in regions change along different paths. All observed dynamic features result from structural rearrange...

The mechanism of sodium migration in low-silica alkali-alkaline earth silicate glasses is investigated through Car-Parrinello molecular dynamics (MD) simulations. The transport of sodium to the glass surface and its subsequent release is critical for the use of these glasses in biomedical applications. The analysis of the MD trajectory, mainly through a combination of space and time correlation...

Biomedical polymer-silicate nanocomposites have potential to become critically important to the development of biomedical applications, ranging from diagnostic and therapeutic devices, tissue regeneration and drug delivery matrixes to various biotechnologies that are inspired by biology but have only indirect biomedical relation. The fundamental understanding of polymer-nanoparticle interaction...

Several studies of internal fiiction have been performed on silicate glasses. This work has the specificity to refer to isothermal mechanical spectroscopy over a large frequency range and for temperatures between 290 K and 520 K. Experiments were carried out with a single alkali silicate glass and two mixed alkali silicate glasses in order to observe the mixed alkali effect, to follow its evolu...

The impact of actinides on the environment is mitigated by their interaction with particle surfaces and by incorporation into suitable waste forms. In both cases, a fundamental knowledge of the local co-ordination environment of actinide ions is essential for understanding their stability in various near-surface environments under a range of conditions. When actinide ions are sorbed on mineral ...

The structure of the alkaline earth silicate glass CaSiO3 has been investigated using a two-dimensional 29Si NMR experiment that correlates the isotropic magic-angle-spinning (MAS) spectrum with an anisotropic off-magic-angle-spinning spectrum. Although the one-dimensional magic-angle-spinning (MAS) spectrum is completely unresolved, all five types of SiO4 tetrahedra (represented by the notatio...