The boson peak in silicate glasses: insight from molecular dynamics.

In the low-frequency regime, ≈1 THz, glasses show an anomalous excess in their vibrational density of states called the boson peak (BP). The origin of BP has been a subject of debate since its first discovery a few decades ago. Although BP has been the focus of numerous studies, no conclusive answers have been found about its origins, which remained elusive to date.

Nucleic Acids under Stress: Understanding and Simulating Nucleobase Fragmentation Pathways.

The effects of radiations on nucleic acids and their constituents is widely studied across several research fields using different experimental and theoretical protocols. While a large number of studies were performed in this context, many fundamental physical and chemical effects are still being investigated, particularly involving the effect of the biological environment. As an example, the interpretation of experimental nucleic acid bases mass spectra, and hence inferring their reactivity in complex environment still poses great challenge.

Atomistic insights into the structure and elasticity of densified 45S5 bioactive glasses.

Glasses have applications in regenerative medicine due to their bioactivity, enabling interactions with hard and soft tissues. Soda-lime phosphosilicate glasses, such as 45S5, represent a model system of bioactive glasses. Regardless of their importance as bioactive materials, the relationship between the structure, density, and cooling process has not been studied in detail.

Structure-Elasticity Relationship of Potassium Silicate Glasses from Brillouin Light Scattering Spectroscopy and Molecular Dynamics Simulations.

Brillouin light scattering (BLS) spectroscopy and molecular dynamic (MD) simulations allowed the identification of a relationship between the elastic properties and the structure of K-containing glasses of formula (KO)-(SiO), having different KO concentrations. Excellent agreement was observed between experimental data and simulations. The peculiar elastic properties observed for these potassium silicate glasses have been extensively discussed in terms of structural and energetic features of the materials.

Ionic self-diffusion and the glass transition anomaly in aluminosilicates.

The glass transition temperature (Tg) is the temperature after which a supercooled liquid undergoes a dynamical arrest. Usually, glass network modifiers (e.g.

Ab Initio Study of the Stepwise versus Concerted Fragmentation Pathways in Microhydrated Thymine Radical Cations.

Thymine radiation-induced fragmentation is characterised by ring opening and the loss of HNCO/NCO. These pathways have been investigated using DFT calculations in the presence of zero, one and two water molecules. In addition to the already characterised stepwise fragmentation mechanism, we propose a novel concerted pathway reported here for the first time.

Ionization and fragmentation of uracil upon microhydration.

We study at the DFT level the ionization and the fragmentation of uracil in the presence of zero, one and two water molecules, to unravel the effect of microhydration on the reactivity of this nucleobase. We show that the microhydration lowers the adiabatic and vertical ionization potentials by 0.41 eV and 0.

Effect of Sodium Oxide Modifier on Structural and Elastic Properties of Silicate Glass.

Molecular dynamics (MD) simulations and Brillouin light scattering (BLS) spectroscopy experiments have been carried to study the structure of sodium silicate glasses (SiO)(NaO), where X ranges from 0 to 45 at room temperature. The MD-obtained glass structures have been subjected to energy minimization at zero temperature to extract the elastic constants also obtained by BLS spectroscopy. The structures obtained are in good agreement with the structural experimental data realized by different techniques.

Highly sensitive pseudo-differential ac-nanocalorimeter for the study of the glass transition.

We present a nanocalorimeter designed for the measurement of the dynamic heat capacity of thin films. The microfabricated sensor, the thermal conditioning of the sensor, as well as the highly stable and low noise electronic chain allow measurements of the real and imaginary parts of the complex specific heat with a resolution Δ C/C of about 10(-5). The performances of this quasi-differential nanocalorimeter were tested on a model of polymeric glass-former, the polyvinyl acetate (PVAc).

The calculation of proton and secondary electron stopping powers in liquid water.

The stopping power of energetic protons in liquid water has been calculated using a new model based on different theoretical and semi-empirical approaches. In this model, we consider the relativistic corrections along with the electronic and nuclear stopping power. The present work accounts for the different interactions made with electrons and nuclei inside the target.